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Asked: 2026-05-13T21:55:05+00:00

I have a data.frame called series_to_plot.df which I created by combining a number of

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I have a data.frame called series_to_plot.df which I created by combining a number of other data.frames together (shown below). I now want to pull out just the .mm column from each of these, so I can plot them. So I want to pull out the 3rd column of each data.frame (e.g. p3c3.mm, p3c4.mm etc…), but I can’t see how to do this for all data.frames in the object without looping through the name. Is this possible?

I can pull out just one set: e.g. series_to_plot.df[[3]] and another by
series_to_plot.df[[10]] (so it is just a list of vectors..) and I can reference directly with series_to_plot.df$p3c3.mm, but is there a command to get a vector containing all mm’s from each data.frame? I was expecting an index something like this to work: series_to_plot.df[,3[3]] but it returns Error in [.data.frame(series_to_plot.df, , 3[3]) : undefined columns selected

series_to_plot.df
          p3c3.rd         p3c3.day    p3c3.mm      p3c3.sd                 p3c3.n p3c3.noo p3c3.no_NAs
    1     2010-01-04             0    0.1702531    0.04003364              7                1           0
    2     2010-01-06             2    0.1790594    0.04696674              7                1           0
    3     2010-01-09             5    0.1720404    0.03801756              8                0           0

          p3c4.rd         p3c4.day    p3c4.mm      p3c4.sd                 p3c4.n p3c4.noo p3c4.no_NAs
    1     2010-01-04             0    0.1076581   0.006542157              6                2           0
    2     2010-01-06             2    0.1393447   0.066758781              7                1           0
    3     2010-01-09             5    0.2056846   0.047722862              7                1           0

          p3c5.rd         p3c5.day    p3c5.mm      p3c5.sd                 p3c5.n p3c5.noo p3c5.no_NAs
    1     2010-01-04             0   0.07987147   0.006508766              7                1           0
    2     2010-01-06             2   0.11496167   0.046478767              8                0           0
    3     2010-01-09             5   0.40326471   0.210217097              7                1           0
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1 Answer

  1. Editorial Team

    To add to the other answers, I don’t think it is a good idea to have useful information encoded in variable names. Much better to rearrange your data so that all useful information is in the value of some variable. I don’t know enough about your data set to suggest the right format, but it might be something like

    p c         rd day date mm sd ...
3 3 2010-10-04 ...

    Once you have done this the answer to your question becomes the simple df$mm.

    If you are getting the data in a less useful form from an external source, you can rearrange it in a more useful form like the above within R using the reshape function or functions from the reshape package.

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