Easy Programming: February 2017

Monday, February 27, 2017

Amazon redshift doc

Amazon redshift doc

https://aws.amazon.com/documentation/redshift/

Some sample amazon redshift code

select c.target, c.dsp from (

SELECT placement,
(case when len(placement)-len(replace(placement,'_','')) >10
then
split_part(placement,'_',9)
end ) as target ,

(case when len(placement)-len(replace(placement,'_','')) >10
then
split_part(placement,'_',6)
end ) as dsp

from

stg.dcm_xxx_placements ) c group by c.target, c.dsp ;

SQL　problem

We have two columns of IDs, id1, id2.

Use a SQL to find out if the two columns of ids have overlaps, i.e., for different ids in id1 they have the same id2's ids, and vice versa.

Friday, February 24, 2017

Realized Netezza, and Amazon redshift are two different systems

Connecting to Amazon redshift using Netezza Aginity.

Want to complete the following:

We have a column of strings in a table in Netezza.

The strings have some underscores. we want to do the following, if a string has more than 10 underscores, we want to get the substring between the 1st and second underscore.

I planed to use the following one:

SELECT str,
case when len(str)-len(replace(str,'_','')) >10
then

substring(str,dlim1+1,(dlim2-dlim1)-1) as column2,

end

And

set dlim1 = charindex('_',str)set dlim2 = charindex('_',str,charindex('_',str)+1)

But it did not work. And I used instr, still not working.

And I found Amazon redshift has the following function:

http://docs.aws.amazon.com/redshift/latest/dg/REGEXP_INSTR.html

And it works.

And here is another function:

http://docs.aws.amazon.com/redshift/latest/dg/SPLIT_PART.html

They both work.

Wednesday, February 22, 2017

longest word

Write a function find_longest_word() that takes a list of words and returns the length of the longest one.

class Solution:
def longest1(self, l1):
len1=len(list(l1[0]))
for i in range(len(l1)):
if len(list(l1[i]))>len1:
len1=len(list(l1[i]))
else:
len1=len1
for i in range(len(l1)):
if len1==len(list(l1[i])):
return(len1,l1[i])
kk=Solution()

if __name__=='__main__':

print(kk.longest1(['aa','etryuiu','adf','erty',]))

max function

The function max() from exercise 1) and the function max_of_three() from exercise 2) will only work for two and three numbers, respectively. But suppose we have a much larger number of numbers, or suppose we cannot tell in advance how many they are? Write a function max_in_list() that takes a list of numbers and returns the largest one.

class Solution:
def max1(self, l1):
max2=l1[0]
for i in range(len(l1)):
if l1[i]>max2:
max2=l1[i]
else:
max2=max2
return(max2)

kk=Solution()
if __name__=='__main__':

print(kk.max1([2,3,1,4,53,6,2,9]))

Results:

overlapping

Define a function overlapping() that takes two lists and returns True if they have at least one member in common, False otherwise. You may use your is_member() function, or the in operator, but for the sake of the exercise, you should (also) write it using two nested for-loops

class Solution:

def overlap(self,l1,l2):
bool1=0
for item in l1:
for item2 in l2:
bool1=bool1+bool(item==item2)
if bool1>0:
return('True')
else:

return('False')

kk=Solution()

if __name__=='__main__':

print(kk.overlap(['a','k','k'],['c','a','b']))

results:

is_member function

Write a function is_member() that takes a value (i.e. a number, string, etc) x and a list of values a, and returns True if x is a member of a, False otherwise. (Note that this is exactly what the in operator does, but for the sake of the exercise you should pretend Python did not have this operator.)

Solution:
def is_member(c,l):
bool1=0
for item in l:
bool1=bool(c==item)+bool1
if bool1>0:
return('True')
else:
return('False')
if __name__=='__main__':

print(is_member('a',['c','a','a']))

Results:

Tuesday, February 21, 2017

Solution to one python question

Write a function char_freq() that takes a string and builds a frequency listing of the characters contained in it. Represent the frequency listing as a Python dictionary. Try it with something like char_freq("abbabcbdbabdbdbabababcbcbab").

class Solution:
def char_freq1(self, string1):
dict={}
a1=list(string1)
for item in a1:
dict[item]=0

for item in a1:
if item in dict.keys():
dict[item]=dict[item]+1
return dict

kk=Solution()

if __name__=="__main__":

print(kk.char_freq1("aaaaadddeerraattqqqiiifehtysjy"))

result:

One solution to a question

Define a procedure histogram() that takes a list of integers and prints a histogram to the screen. For example, histogram([4, 9, 7]) should print the following:

****
*********
*******

class Solution:
def hist1(self,vector):
a1=[0]*len(vector)
for i in range(len(vector)):
a1[i]='*'*vector[i]
for j in range(len(a1)):
print(a1[j])

kk=Solution()
if __name__=="__main__":

kk.hist1([2,5,8])

results:

Thursday, February 16, 2017

A python problem and the solution

Define a function generate_n_chars() that takes an integer n and a character c and returns a string, n characters long, consisting only of c:s. For example, generate_n_chars(5,"x") should return the string "xxxxx". (Python is unusual in that you can actually write an expression 5 * "x" that will evaluate to "xxxxx". For the sake of the exercise you should ignore that the problem can be solved in this manner.)

Solution:

class Solution:
def generator1(self,a,n):
i=0
x=''
while i<n:
x=x+a
i=i+1

return(x)
kk=Solution()

print(kk.generator1('i',9))

result:

Another problem using bool

testing if an item is in a list, not use in.

class Solution:
def is_member(self, a,x):
bool1=0
for i in range(len(x)):
bool1=bool1+bool(a==x[i])

if bool1==0:
return('False')

if bool1>0:
return('True')

Python bool function and a python program

bool function will return false or true for a statement.

And we can apply arithmetic operations on it. Here are some examples.

Here is one example, testing a string is palindrome or not:

class Solution:
def is_palindrome(self, x1):
bool1=1
list1=list(x1)
for i in range(int(len(list1)/2)):
bool1=bool(list1[i]==list1[len(list1)-1-i])*bool1

if bool1==1:
return('True')
else:
return('False')

kk=Solution()
print(kk.is_palindrome('aba'))

Results:

True

Five mini python projects and the solutions

Five mini python projects and the solutions

http://knightlab.northwestern.edu/2014/06/05/five-mini-programming-projects-for-the-python-beginner/

1. roll a dice

import random

def ran1(x):
     r1=random.randint(1,x)
   print(r1)

if __name__=="__main__":
   ran1(6)

Linux weekly news

Linux weekly news:

https://lwn.net/

Python creating your own project structure

Python creating your own project structure:

https://coderwall.com/p/lt2kew/python-creating-your-project-structure

collections of python projects

collections of python projects

http://code.activestate.com/recipes/langs/python/?query_start=1

http://planetpython.org/

http://www.pythonforbeginners.com/code-snippets-source-code/python-code-examples

Wednesday, February 15, 2017

reverse a string

reverse a string, python code:

class Solution:
def rev1(self, string1):
k1=list(string1)
print(k1)
for i in range(int(len(k1)/2)):
k1[i],k1[len(k1)-1-i]=k1[len(k1)-1-i],k1[i]
k2=''.join(k1)
return(k2)

46 Simple Python Exercises

This is version 0.45 of a collection of simple Python exercises constructed (but in many cases only found and collected) by Torbjörn Lager (torbjorn.lager@ling.gu.se). Most of them involve characters, words and phrases, rather than numbers, and are therefore suitable for students interested in language rather than math.

Very simple exercises

Define a function max() that takes two numbers as arguments and returns the largest of them. Use the if-then-else construct available in Python. (It is true that Python has the max() function built in, but writing it yourself is nevertheless a good exercise.)
Define a function max_of_three() that takes three numbers as arguments and returns the largest of them.
Define a function that computes the length of a given list or string. (It is true that Python has the len() function built in, but writing it yourself is nevertheless a good exercise.)
Write a function that takes a character (i.e. a string of length 1) and returns True if it is a vowel, False otherwise.
Write a function translate() that will translate a text into "rövarspråket" (Swedish for "robber's language"). That is, double every consonant and place an occurrence of "o" in between. For example, translate("this is fun") should return the string "tothohisos isos fofunon".
Define a function sum() and a function multiply() that sums and multiplies (respectively) all the numbers in a list of numbers. For example, sum([1, 2, 3, 4]) should return 10, and multiply([1, 2, 3, 4]) should return 24.
Define a function reverse() that computes the reversal of a string. For example, reverse("I am testing") should return the string "gnitset ma I".
Define a function is_palindrome() that recognizes palindromes (i.e. words that look the same written backwards). For example, is_palindrome("radar") should return True.
Write a function is_member() that takes a value (i.e. a number, string, etc) x and a list of values a, and returns True if x is a member of a, False otherwise. (Note that this is exactly what the in operator does, but for the sake of the exercise you should pretend Python did not have this operator.)
Define a function overlapping() that takes two lists and returns True if they have at least one member in common, False otherwise. You may use your is_member() function, or the in operator, but for the sake of the exercise, you should (also) write it using two nested for-loops.
Define a function generate_n_chars() that takes an integer n and a character c and returns a string, n characters long, consisting only of c:s. For example, generate_n_chars(5,"x") should return the string "xxxxx". (Python is unusual in that you can actually write an expression 5 * "x" that will evaluate to "xxxxx". For the sake of the exercise you should ignore that the problem can be solved in this manner.)
Define a procedure histogram() that takes a list of integers and prints a histogram to the screen. For example, histogram([4, 9, 7]) should print the following:
```
****
*********
*******
```
The function max() from exercise 1) and the function max_of_three() from exercise 2) will only work for two and three numbers, respectively. But suppose we have a much larger number of numbers, or suppose we cannot tell in advance how many they are? Write a function max_in_list() that takes a list of numbers and returns the largest one.
Write a program that maps a list of words into a list of integers representing the lengths of the correponding words.
Write a function find_longest_word() that takes a list of words and returns the length of the longest one.
Write a function filter_long_words() that takes a list of words and an integer n and returns the list of words that are longer than n.
Write a version of a palindrome recognizer that also accepts phrase palindromes such as "Go hang a salami I'm a lasagna hog.", "Was it a rat I saw?", "Step on no pets", "Sit on a potato pan, Otis", "Lisa Bonet ate no basil", "Satan, oscillate my metallic sonatas", "I roamed under it as a tired nude Maori", "Rise to vote sir", or the exclamation "Dammit, I'm mad!". Note that punctuation, capitalization, and spacing are usually ignored.
A pangram is a sentence that contains all the letters of the English alphabet at least once, for example: The quick brown fox jumps over the lazy dog. Your task here is to write a function to check a sentence to see if it is a pangram or not.
"99 Bottles of Beer" is a traditional song in the United States and Canada. It is popular to sing on long trips, as it has a very repetitive format which is easy to memorize, and can take a long time to sing. The song's simple lyrics are as follows:

99 bottles of beer on the wall, 99 bottles of beer.
Take one down, pass it around, 98 bottles of beer on the wall.
The same verse is repeated, each time with one fewer bottle. The song is completed when the singer or singers reach zero.
Your task here is write a Python program capable of generating all the verses of the song.
Represent a small bilingual lexicon as a Python dictionary in the following fashion {"merry":"god", "christmas":"jul", "and":"och", "happy":gott", "new":"nytt", "year":"år"} and use it to translate your Christmas cards from English into Swedish. That is, write a function translate() that takes a list of English words and returns a list of Swedish words.
Write a function char_freq() that takes a string and builds a frequency listing of the characters contained in it. Represent the frequency listing as a Python dictionary. Try it with something like char_freq("abbabcbdbabdbdbabababcbcbab").
In cryptography, a Caesar cipher is a very simple encryption techniques in which each letter in the plain text is replaced by a letter some fixed number of positions down the alphabet. For example, with a shift of 3, A would be replaced by D, B would become E, and so on. The method is named after Julius Caesar, who used it to communicate with his generals. ROT-13 ("rotate by 13 places") is a widely used example of a Caesar cipher where the shift is 13. In Python, the key for ROT-13 may be represented by means of the following dictionary:
```
key = {'a':'n', 'b':'o', 'c':'p', 'd':'q', 'e':'r', 'f':'s', 'g':'t', 'h':'u', 
       'i':'v', 'j':'w', 'k':'x', 'l':'y', 'm':'z', 'n':'a', 'o':'b', 'p':'c', 
       'q':'d', 'r':'e', 's':'f', 't':'g', 'u':'h', 'v':'i', 'w':'j', 'x':'k',
       'y':'l', 'z':'m', 'A':'N', 'B':'O', 'C':'P', 'D':'Q', 'E':'R', 'F':'S', 
       'G':'T', 'H':'U', 'I':'V', 'J':'W', 'K':'X', 'L':'Y', 'M':'Z', 'N':'A', 
       'O':'B', 'P':'C', 'Q':'D', 'R':'E', 'S':'F', 'T':'G', 'U':'H', 'V':'I', 
       'W':'J', 'X':'K', 'Y':'L', 'Z':'M'}
```
Your task in this exercise is to implement an encoder/decoder of ROT-13. Once you're done, you will be able to read the following secret message:
```
   Pnrfne pvcure? V zhpu cersre Pnrfne fnynq!
```
Note that since English has 26 characters, your ROT-13 program will be able to both encode and decode texts written in English.
Define a simple "spelling correction" function correct() that takes a string and sees to it that 1) two or more occurrences of the space character is compressed into one, and 2) inserts an extra space after a period if the period is directly followed by a letter. E.g. correct("This is very funny and cool.Indeed!") should return "This is very funny and cool. Indeed!" Tip: Use regular expressions!
The third person singular verb form in English is distinguished by the suffix -s, which is added to the stem of the infinitive form: run -> runs. A simple set of rules can be given as follows:
1. If the verb ends in y, remove it and add ies
2. If the verb ends in o, ch, s, sh, x or z, add es
3. By default just add s
Your task in this exercise is to define a function make_3sg_form() which given a verb in infinitive form returns its third person singular form. Test your function with words like try, brush, run and fix. Note however that the rules must be regarded as heuristic, in the sense that you must not expect them to work for all cases. Tip: Check out the string method endswith().
In English, the present participle is formed by adding the suffix -ing to the infinite form: go -> going. A simple set of heuristic rules can be given as follows:
1. If the verb ends in e, drop the e and add ing (if not exception: be, see, flee, knee, etc.)
2. If the verb ends in ie, change ie to y and add ing
3. For words consisting of consonant-vowel-consonant, double the final letter before adding ing
4. By default just add ing
Your task in this exercise is to define a function make_ing_form() which given a verb in infinitive form returns its present participle form. Test your function with words such as lie, see, move and hug. However, you must not expect such simple rules to work for all cases.

Higher order functions and list comprehensions

Using the higher order function reduce(), write a function max_in_list() that takes a list of numbers and returns the largest one. Then ask yourself: why define and call a new function, when I can just as well call the reduce() function directly?
Write a program that maps a list of words into a list of integers representing the lengths of the correponding words. Write it in three different ways: 1) using a for-loop, 2) using the higher order function map(), and 3) using list comprehensions.
Write a function find_longest_word() that takes a list of words and returns the length of the longest one. Use only higher order functions.
Using the higher order function filter(), define a function filter_long_words() that takes a list of words and an integer n and returns the list of words that are longer than n.
Represent a small bilingual lexicon as a Python dictionary in the following fashion {"merry":"god", "christmas":"jul", "and":"och", "happy":gott", "new":"nytt", "year":"år"} and use it to translate your Christmas cards from English into Swedish. Use the higher order function map() to write a function translate() that takes a list of English words and returns a list of Swedish words.
Implement the higher order functions map(), filter() and reduce(). (They are built-in but writing them yourself may be a good exercise.)

Simple exercises including I/O

Write a version of a palindrome recogniser that accepts a file name from the user, reads each line, and prints the line to the screen if it is a palindrome.
According to Wikipedia, a semordnilap is a word or phrase that spells a different word or phrase backwards. ("Semordnilap" is itself "palindromes" spelled backwards.) Write a semordnilap recogniser that accepts a file name (pointing to a list of words) from the user and finds and prints all pairs of words that are semordnilaps to the screen. For example, if "stressed" and "desserts" is part of the word list, the the output should include the pair "stressed desserts". Note, by the way, that each pair by itself forms a palindrome!
Write a procedure char_freq_table() that, when run in a terminal, accepts a file name from the user, builds a frequency listing of the characters contained in the file, and prints a sorted and nicely formatted character frequency table to the screen.
The International Civil Aviation Organization (ICAO) alphabet assigns code words to the letters of the English alphabet acrophonically (Alfa for A, Bravo for B, etc.) so that critical combinations of letters (and numbers) can be pronounced and understood by those who transmit and receive voice messages by radio or telephone regardless of their native language, especially when the safety of navigation or persons is essential. Here is a Python dictionary covering one version of the ICAO alphabet:
```
d = {'a':'alfa', 'b':'bravo', 'c':'charlie', 'd':'delta', 'e':'echo', 'f':'foxtrot',
     'g':'golf', 'h':'hotel', 'i':'india', 'j':'juliett', 'k':'kilo', 'l':'lima',
     'm':'mike', 'n':'november', 'o':'oscar', 'p':'papa', 'q':'quebec', 'r':'romeo',
     's':'sierra', 't':'tango', 'u':'uniform', 'v':'victor', 'w':'whiskey', 
     'x':'x-ray', 'y':'yankee', 'z':'zulu'}
```
Your task in this exercise is to write a procedure speak_ICAO() able to translate any text (i.e. any string) into spoken ICAO words. You need to import at least two libraries: os and time. On a mac, you have access to the system TTS (Text-To-Speech) as follows: os.system('say ' + msg), where msg is the string to be spoken. (Under UNIX/Linux and Windows, something similar might exist.) Apart from the text to be spoken, your procedure also needs to accept two additional parameters: a float indicating the length of the pause between each spoken ICAO word, and a float indicating the length of the pause between each word spoken.
A hapax legomenon (often abbreviated to hapax) is a word which occurs only once in either the written record of a language, the works of an author, or in a single text. Define a function that given the file name of a text will return all its hapaxes. Make sure your program ignores capitalization.
Write a program that given a text file will create a new text file in which all the lines from the original file are numbered from 1 to n (where n is the number of lines in the file).
Write a program that will calculate the average word length of a text stored in a file (i.e the sum of all the lengths of the word tokens in the text, divided by the number of word tokens).

Write a program able to play the "Guess the number"-game, where the number to be guessed is randomly chosen between 1 and 20. (Source: http://inventwithpython.com) This is how it should work when run in a terminal:

>>> import guess_number
Hello! What is your name?
Torbjörn
Well, Torbjörn, I am thinking of a number between 1 and 20.
Take a guess.
10
Your guess is too low.
Take a guess.
15
Your guess is too low.
Take a guess.
18
Good job, Torbjörn! You guessed my number in 3 guesses!

An anagram is a type of word play, the result of rearranging the letters of a word or phrase to produce a new word or phrase, using all the original letters exactly once; e.g., orchestra = carthorse, A decimal point = I'm a dot in place. Write a Python program that, when started 1) randomly picks a word w from given list of words, 2) randomly permutes w (thus creating an anagram of w), 3) presents the anagram to the user, and 4) enters an interactive loop in which the user is invited to guess the original word. It may be a good idea to work with (say) colour words only. The interaction with the program may look like so:
```
>>> import anagram
Colour word anagram: onwbr
Guess the colour word!
black
Guess the colour word!
brown
Correct!
```
In a game of Lingo, there is a hidden word, five characters long. The object of the game is to find this word by guessing, and in return receive two kinds of clues: 1) the characters that are fully correct, with respect to identity as well as to position, and 2) the characters that are indeed present in the word, but which are placed in the wrong position. Write a program with which one can play Lingo. Use square brackets to mark characters correct in the sense of 1), and ordinary parentheses to mark characters correct in the sense of 2). Assuming, for example, that the program conceals the word "tiger", you should be able to interact with it in the following way:
```
>>> import lingo
snake
Clue: snak(e)
fiest
Clue: f[i](e)s(t)
times
Clue: [t][i]m[e]s
tiger
Clue: [t][i][g][e][r]
```

Somewhat harder exercises

A sentence splitter is a program capable of splitting a text into sentences. The standard set of heuristics for sentence splitting includes (but isn't limited to) the following rules:
Sentence boundaries occur at one of "." (periods), "?" or "!", except that
1. Periods followed by whitespace followed by a lower case letter are not sentence boundaries.
2. Periods followed by a digit with no intervening whitespace are not sentence boundaries.
3. Periods followed by whitespace and then an upper case letter, but preceded by any of a short list of titles are not sentence boundaries. Sample titles include Mr., Mrs., Dr., and so on.
4. Periods internal to a sequence of letters with no adjacent whitespace are not sentence boundaries (for example, www.aptex.com, or e.g).
5. Periods followed by certain kinds of punctuation (notably comma and more periods) are probably not sentence boundaries.
Your task here is to write a program that given the name of a text file is able to write its content with each sentence on a separate line. Test your program with the following short text: Mr. Smith bought cheapsite.com for 1.5 million dollars, i.e. he paid a lot for it. Did he mind? Adam Jones Jr. thinks he didn't. In any case, this isn't true... Well, with a probability of .9 it isn't. The result should be:
```
Mr. Smith bought cheapsite.com for 1.5 million dollars, i.e. he paid a lot for it.
Did he mind?
Adam Jones Jr. thinks he didn't.
In any case, this isn't true...
Well, with a probability of .9 it isn't.
```
An anagram is a type of word play, the result of rearranging the letters of a word or phrase to produce a new word or phrase, using all the original letters exactly once; e.g., orchestra = carthorse. Using the word list at http://www.puzzlers.org/pub/wordlists/unixdict.txt, write a program that finds the sets of words that share the same characters that contain the most words in them.
Your task in this exercise is as follows:
- Generate a string with N opening brackets ("[") and N closing brackets ("]"), in some arbitrary order.
- Determine whether the generated string is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.
Examples:
```
   []        OK   ][        NOT OK
   [][]      OK   ][][      NOT OK
   [[][]]    OK   []][[]    NOT OK
```
A certain childrens game involves starting with a word in a particular category. Each participant in turn says a word, but that word must begin with the final letter of the previous word. Once a word has been given, it cannot be repeated. If an opponent cannot give a word in the category, they fall out of the game. For example, with "animals" as the category,
```
Child 1: dog 
Child 2: goldfish
Child 1: hippopotamus
Child 2: snake
...
```
Your task in this exercise is as follows: Take the following selection of 70 English Pokemon names (extracted from Wikipedia's list of Pokemon) and generate the/a sequence with the highest possible number of Pokemon names where the subsequent name starts with the final letter of the preceding name. No Pokemon name is to be repeated.
```
audino bagon baltoy banette bidoof braviary bronzor carracosta charmeleon
cresselia croagunk darmanitan deino emboar emolga exeggcute gabite
girafarig gulpin haxorus heatmor heatran ivysaur jellicent jumpluff kangaskhan
kricketune landorus ledyba loudred lumineon lunatone machamp magnezone mamoswine
nosepass petilil pidgeotto pikachu pinsir poliwrath poochyena porygon2
porygonz registeel relicanth remoraid rufflet sableye scolipede scrafty seaking
sealeo silcoon simisear snivy snorlax spoink starly tirtouga trapinch treecko
tyrogue vigoroth vulpix wailord wartortle whismur wingull yamask
```
An alternade is a word in which its letters, taken alternatively in a strict sequence, and used in the same order as the original word, make up at least two other words. All letters must be used, but the smaller words are not necessarily of the same length. For example, a word with seven letters where every second letter is used will produce a four-letter word and a three-letter word. Here are two examples:
```
  "board": makes "bad" and "or".
  "waists": makes "wit" and "ass".
```
Using the word list at http://www.puzzlers.org/pub/wordlists/unixdict.txt, write a program that goes through each word in the list and tries to make two smaller words using every second letter. The smaller words must also be members of the list. Print the words to the screen in the above fashion.

Python practice problems websites

1. codecademy
2. https://www.udemy.com/complete-python-bootcamp/
3. udacity nanodegree

4.https://www.codingame.com
5. https://codefights.com/
6. http://www.checkio.org
7. http://www.pythonchallenge.com/
8. http://projecteuler.net/
9. http://www.ling.gu.se/~lager/python_exercises.html

Tuesday, February 14, 2017

My atom editor and which program I use to run the programs.

I use Atom editor on my windows. It can also be installed on Linux, Mac.

And I use the Atom runner to run the script. It can run R, Python, Perl, etc.

Here are the usage:

Hit Ctrl+R (Alt+R on Win/Linux) to launch the runner for the active window.

Hit Ctrl+Shift+R (Alt+Shift+R on Win/Linux) to run the currently selected text in the active window.

Hit Ctrl+Shift+C to kill a currently running process.

Hit Escape to close the runner window.

https://atom.io/packages/atom-runner

There is a script-runner, was told better than atom-runner. But I can not install it on my working computer because of security.

https://atom.io/packages/script-runner

https://www.youtube.com/watch?v=QyVnWjZzGVY

https://www.youtube.com/watch?v=Ylv4dCPbmRQ

https://www.youtube.com/watch?v=nTdTBs6jk98

https://www.youtube.com/watch?v=tSyBMPg3bsQ

A python problem and its solution.

Write a program to calculate and display the sum of the series:

1 - 1/2 + 1/3 - 1/4 + ...

until a term is reached that is less than 0.0001.

Here is the program:

def aa(n):

a=0

if n>0:

for i in range(1,n,1):

a=a+(-1)**(i-1)*(1/i)

return(a)

e=0.01

n=1

while e>0.0001:

e=abs(aa(n+1)-aa(n))

n=n+1

if e<0.0001:

print(e,aa(n),n)

And it converged. Results:

If you are running windows, and you plan to write a program in Python, which IDE( platform) you will use? and my answer.

If you are running windows, and you plan to write a program in Python, which IDE( platform) you will use?

I was thinking about this question once when I was trying to write a program in python.

And the fact is that, when I try to write a relatively bigger script, I use Atom. I am using Atom-runner and to run the script etc, I use the following commands:

https://atom.io/packages/atom-runner

Atom is my first choice currently.

I have pycharm, spyder, jupiter too. But the first thing I think of is Atom. Pycharm, Spyder, Jupiter are good too.

And if I want to test one line, I use Python IDLE.

There is another IDE, eclipse. They can run python too.

If you use Linux, you can use the terminal, Atom etc.

Python sequence of numbers

Python sequence of numbers, starting from 0:

range(5)

python sequence of numbers, starting from 1:

range(1,5,1)

Python range and xrange:

http://pythoncentral.io/how-to-use-pythons-xrange-and-range/

Monday, February 13, 2017

A data science blog collection and a post

data science blog collection

datatau.com

A post

http://blog.aylien.com/sentiment-analysis-of-2-2-million-tweets-from-super-bowl-51/

Friday, February 10, 2017

How to learn to code, videos

How to learn to code, 5 easy steps

part 1

https://www.youtube.com/watch?v=1uEUTijqoE0

part 2

https://www.youtube.com/watch?v=GHwwnJ8S7SQ

A longer video

https://www.youtube.com/watch?v=GHwwnJ8S7SQ

Another one:

https://www.youtube.com/watch?v=2nnteBL1ZFQ

https://www.youtube.com/watch?v=1p5ERhluxd8

Thursday, February 9, 2017

Learn Javascript and coffee script

Learn Javascript in 12 mins:

https://www.youtube.com/watch?v=Ukg_U3CnJWI

javascript tutorial

http://www.tutorialspoint.com/javascript/javascript_tutorial.pdf

javascript wiki

https://en.wikipedia.org/wiki/JavaScript

coffee script:

http://coffeescript.org/

https://en.wikipedia.org/wiki/CoffeeScript

https://arcturo.github.io/library/coffeescript/02_syntax.html

Wednesday, February 8, 2017

How a guy got offer from google within 8 months starting from a green hand in CS. Not me. I wrote it down with first person.

I got the offer within 8 months starting from a green hand in CS.

I applied to more than 100 companies. I got interviews from 30 companies. And 11 companies interviewed me onsite. The first 7 companies did not give me offer. During the last 4 interviews, I got offer from 3 big companies and 1 startup. At last, I accept offer from G.

My background

A bludger of software engineering major before, could not recognize ‘main’ in Java/C++. Did not finish even 100 rows of code. The foundation of CS knowledge is extremely sprawling and tousy. Studied CS master in US for one year in US. Got in the program in 09/2012, started finding a job in 01/2013, not big difference than I was when graduating with BS.

All in all, five points for me:

Knowledge
Practice
Goal
Mind-set
Skills

1. Knowledge

Master a programming language. I choose Python. Its syntax and data structures are simple enough. It lets me focus more on usage of programming language-apply to data structures.

Rudiments:

https://www.codecademy.com/

Learn Python basic on codecademy.

Applications:

Wrote down the python code for cracking the coding interview. And then I can gradually understand Python documentation.

Data structures and algorithms:

Data structures. Found out some online ppt or online class to study.

Algorithms. Not so useful for finding jobs. Got to know the most used ones for data structures. (DFS etc) and dynamic programming.

Practice

Apply the language I learned and the algorithms onto data structures. Method is drilling through the coding interview questions. I drilled through cracking the coding interview. I drilled through the interview questions for 5 times. And after that, before each interview, I drilled through it once.

CS attainment

After drilling through the coding questions. I thought I was good enough. But I was still rejected. And I found that each time talking with the interviewers, I lacked the CS attainment, some basic knowledge and the relationship between all the knowledge.

Rudiments

A quick way to get to know comprehensive CS knowledge.

http://www.programmerinterview.com/

Recite main sections twice. Sometimes, it helped on interviews. But I still did not master the knowledge comprehensively and understand the knowledge.

Get deeper into the knowledge

Data structures
Algorithms
Database
Operating systems

You must have all the four classes. Some fancy classes may not be so helpful for finding a general developer position. If you did not have the classes, then go online for the classes.

Recommending Berkeley CS classes:

Set up the way of thinking in CS

Structure and interpretation of computer programming

https://www.youtube.com/playlist?list=PL3E89002AA9B9879E

Progress

Studied comprehensively.

To accomplish the knowledge systems, quickly studied the below:

A. Language:

Java, C++

Find books for the languages. Spent hours on them. To see what data structures are called here,

and how to apply them.

B. Front end:

HTML, CSS, JQuery, XML

Read each part from W3C school.

C. Linux command

D. Web Development

Django

E. Mobile

Android: online course ( udemy)

iOS: iOS programming

F. Others

Design Pattern: online course (udemy)

Programming pearls

Complete the book for two days before being interviewed by google. CC150 and leetcode taught me the methods. This book taught me methodologies. The way of thinking from low level to think high level.

2. Practice

Drilling through the coding questions and the CS knowledge help me to have the lego. But I was not confident because I do not have a masterpiece of my own. So, go to write and build my projects. I wrote a side project, such as I wrote an iOS app. You can also write some course projects, or find some projects from your professors.

3. Goal

Must

If you want to find a CS job, you can definitely find one. So, do not have some backup, like going back to original country, continue studying etc. When you have a definite goal, everything becomes simple and definite.

List and source.

At the end of August, I had graduated for around 3 months, I did not find a job. I felt I had interviewed most of the companies that I want to be interviewed. But it was not. So, I spent 2 hours, listing all the companies that I want to have interviews, but I did not. Altogether, 25. I look around to see if I can find someone to refer me to those companies. If there was not, I tried to find the referrals from forums. At last, I got referrals from 22 companies.

Ally

To find the friends nearby to fight for the same goal, work hard together.

4. Mind-set

Confidence

After drilling through so many questions, and studying so much knowledge, building so many

Projects, confidence will come. And some day, a voice is telling me, ‘I am ready’.

Belief

How big your desire is , then how big your belief will be.

You can do meditation, imagine one day, you got the offer.

c. The more failures you got, the more you want to go to the interviews.

Keep practicing your interview skills. If you find some loophole in your knowledge, then you go

to do the makeup soon.

5. Interview skills

Introducing your background. Carefully prepare your education background, and your projects. Face to the mirror and practice them. You can also find some friends to do the mock interview.

Prepare 3 interview questions, about the company’s products, future, the team, skilled used in the team etc. Let them feel your interests and enthusiasm.

Smile. When you enter the company to onsite. Tell yourself, you need to smile. Then all the problems will be resolved.

ezoic