how to extract a same name factor in many dataframe

Question

I have 4 data frame:

temp2011, temp2012, temp2013, temp2014

These dataframe have same column name. (date, temp, humid, rain) I want to extract a column like this:

temp2011$temp
temp2012$temp
temp2013$temp
temp2014$temp

It is very hassle, so I change the code like this:

col <- "temp"
temp2011$col
temp2012$col
temp2013$col
temp2014$col

but this is not work.

How can I do this problem.

It's a little unclear what you want to do. Do you just need to get a column from one data set? Changing `temp` to `col` has no effect in my opinion. Are these merged data sets? — NelsonGon, May 01 '19 at 12:56

score 2 · Answer 1 · answered May 01 '19 at 12:52

2

Use [[]] instead of $ as temp2011[[col]]

answered May 01 '19 at 12:52

Sonny

Why should `$` fail in this case? – NelsonGon May 01 '19 at 13:01
1

`col` is a variable whose value is `temp`, so `temp2011$col` should give `NULL` – Sonny May 01 '19 at 13:03

1 Answers1