How to drop columns in a nested data frame in R?

Question

As i know there are different ways to drop a column of a data frame in R like

How to drop columns by name in a data frame

Remove an entire column from a data.frame in R

Now My question: I have a data frame say df having 400 plus files in the form of nested data frame.

        df
    [[1]]
                SignalIntensity SNR
        1   109 6.1823089314    0.8453576915
        2   110 10.1727771385   4.3837077591
        3   111 7.2922746927    1.0725751161
        4   112 8.8984671629    2.3192184908
        5   113 9.5910338232    3.7133402249
        6   114 7.9850187685    1.5008899345
        7   116 7.7893230124    1.3636655582
                       .
                       .
                       .
    [[2]]

            SignalIntensity SNR
    1   109 6.1823089314    0.8453576915
    2   110 10.1727771385   4.3837077591
    3   111 7.2922746927    1.0725751161
    4   112 8.8984671629    2.3192184908
    5   113 9.5910338232    3.7133402249
    6   114 7.9850187685    1.5008899345
    7   116 7.7893230124    1.3636655582
                  .
                  .
                  .
[[3]]

        ID  SignalIntensity SNR
    1   109 6.1823089314    0.8453576915
    2   110 10.1727771385   4.3837077591
    3   111 7.2922746927    1.0725751161
    4   112 8.8984671629    2.3192184908
    5   113 9.5910338232    3.7133402249
    6   114 7.9850187685    1.5008899345
    7   116 7.7893230124    1.3636655582
                   .
                   .
                   .
 and so on.....

I want to remove column 1 from all the 400 plus files. The column 1 header may be present or absent.

I know to use df[[1]][,-1] to remove column 1 of first file. In order to do for all the files i have to repeat it 400 or so times to make the work done. There may be 1 or 2 line of code in R to do this. How?? help appreciated.

Final data frame is expected to be like

df
     [[1]]
                    SignalIntensity SNR
            1       6.1823089314    0.8453576915
            2       10.1727771385   4.3837077591
            3       7.2922746927    1.0725751161
            4       8.8984671629    2.3192184908
            5       9.5910338232    3.7133402249
            6       7.9850187685    1.5008899345
            7       7.7893230124    1.3636655582
                           .
                           .
                           .
        [[2]]

                SignalIntensity SNR
        1       6.1823089314    0.8453576915
        2       10.1727771385   4.3837077591
        3       7.2922746927    1.0725751161
        4       8.8984671629    2.3192184908
        5       9.5910338232    3.7133402249
        6       7.9850187685    1.5008899345
        7       7.7893230124    1.3636655582
                      .
                      .
                      .
    [[3]]

                SignalIntensity SNR
        1       6.1823089314    0.8453576915
        2       10.1727771385   4.3837077591
        3       7.2922746927    1.0725751161
        4       8.8984671629    2.3192184908
        5       9.5910338232    3.7133402249
        6       7.9850187685    1.5008899345
        7       7.7893230124    1.3636655582
                       .
                       .
                       .
     and so on.....

Dominic Comtois · Accepted Answer · 2015-03-14 07:39:37Z

6

One option is with a loop:

for(i in seq_along(df)) {
  df[[i]] <- df[[i]][-1]
}

Or without the loop, using lapply:

df2 <- lapply(df, subset, select=-1)

edited Mar 14, 2015 at 7:39

answered Mar 14, 2015 at 7:32

Dominic Comtois

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2 Comments

Agaz Wani Over a year ago

Thanks for your comments. Isn't there any thing without loop

Agaz Wani Over a year ago

Great. This is what i was looking forward.

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