Components of list

Question

dfmerge_BR = read.csv(file ="dfmerge_BR.csv", header=TRUE)
dfmerge_CO = read.csv(file ="dfmerge_CO.csv", header=TRUE)
dfmerge_BL = read.csv(file ="dfmerge_BL.csv", header=TRUE)
dfmerge_KC = read.csv(file ="dfmerge_KC.csv", header=TRUE)
dflist <- list(dfmerge_BR,dfmerge_CO,dfmerge_BL, dfmerge_KC)

new_list <-  lapply(dflist, function(x) x[1,])

}

I have four different csv files here, I read them and put them into the list. I iterated through the list of data frames such that I choose first row of each data frame(now the component of list) and assign them to new_list. Now I want to extract the each component of list. but when I do

a <- new_list[[1]]
b <- new_list[[2]]

When I view both the vectors, vector b has all the values as NA and also why the a and b aren't data frames but vectors?

Returns the same result as @seekheart answer i.e. a vector not a list! — vib321, Mar 01 '16 at 13:49
`lapply` returns a list by definition. I have no idea what are you talking about. Try `class(lapply(dflist, head, 1))`. A list is a vector too btw. And a `data.frame` is a list too. Try `lapply(lapply(dflist, head, 1), is.list)` so your statement is invalid. — David Arenburg, Mar 01 '16 at 13:50

score 3 · Accepted Answer · answered Mar 01 '16 at 13:43

3

if you want the first of every data frame then do this.

new_list <- lapply(dflist, function(x) x[1,])

answered Mar 01 '16 at 13:43

Seekheart

1,135
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Or just ```lapply(dflist, `[`, 1,)``` – David Arenburg Mar 01 '16 at 13:48

Components of list

1 Answers1