Apply, sapply, tapply differences in R

https://www.guru99.com/r-apply-sapply-tapply.html

Apply: on matrice

apply(mat,1,var)


1: row,  margin
2:column, margin


lapply: apply on a vector, return a list, no margin

movies <- c("SPYDERMAN","BATMAN","VERTIGO","CHINATOWN")
movies_lower <-lapply(movies, tolower)
[[1]]
[1] "spyderman"
[[2]]
[1]"batman"
...

sapply does the same job as lapply, but return a vector


tapply computes a measure ( min, max, median etc) or a function for each factor variable in a vector.

data(iris)

tapply(iris$Sepal.Width, iris$Species, median)

https://www.r-bloggers.com/using-apply-sapply-lapply-in-r/