lapply() function is useful for performing operations on list objects and returns a list object of same length of original set. lappy() returns a list of the similar length as input list object, each element of which is the result of applying FUN to the corresponding element of list. Lapply in R takes list, vector or data frame as input and gives output in list.
**lapply(X, FUN) **
** -X: A vector or an object **
-FUN: Function applied to each element of x
l in lapply() stands for list. The difference between lapply() and apply() lies between the output return. The output of lapply() is a list. lapply() can be used for other objects like data frames and lists.
lapply() function does not need MARGIN.
A very easy example can be to change the string value of a matrix to lower case with tolower function. We construct a matrix with the name of the famous movies. The name is in upper case format.
movies ← c(“SPYDERMAN”,“BATMAN”,“VERTIGO”,“CHINATOWN”)
movies_lower <-lapply(movies, tolower)
We can use unlist() to convert the list into a vector.
movies_lower <-unlist(lapply(movies,tolower)) str(movies_lower)
## chr [1:4] “spyderman” “batman” “vertigo” "chinatown"