Subset data frames stored inside a list in R by same column name

Question

[paolo002]

Hi all

I have multiple csv files stored in a list (list.data) having same column names but different data frame names. I would like to subset a column (CHR) by a specific value (1) and apply it to all the data frames in the list and to all the columns.

I wrote this code :

CHR1<-lapply(list.data, function(x) { x["CHR"] = 1; x }

However this seem to subset correctly that specific column (CHR) but the other columns did not change, subset was not applied to the rest of the columns.

I wrote also this code but it returns an empty list

CHR1<-lapply(list.data, subset, "CHR"=1)

Any help highly appreciated. Thanks

Answer 1

[zx8754]

Try:

CHR1 <- lapply(list.data, function(x) { x[ x$CHR == 1, ] })

• = is an assignment operator, e.g.: myVar = 1; print(myVar) same as <-.

• == is a logical operator, used for comparing, e.g.: 1 == 2 this will give us FALSE.

[paolo002]

Thank you very much for your help once again. It worked. And thanks for the explanation.