How to subset data.frames stored in a list?

Question

I created a list and I stored one data frame in each component. Now I would like to filter those data frames keeping only the rows that have NA in a specific column. I would

Answer 1

lapply's second argument is a function (subset) and extra arguments to subset are passed as the ... arguments to lapply. Hence:

my.ls <- list(d1 = d1, d2 = d2)
my.lsNA <- lapply(my.ls, subset, is.na(b))

(I am also showing you how to easily create the list of data.frames without using get, and recommend you don't use ls as a variable name since it is also the name of a rather common function.)

Answer 2

Regarding the question in @Riccardo's last comment, try:

lapply(my.ls, "[", 1)

or alternately:

lapply(my.ls, "[[", 1)

depending on whether you want the output to be a list of dataframes or a list of vectors.