[R] how to best add columns to a matrix with many columns

Jeff Newmiller jdnewmil at dcn.davis.CA.us
Sat May 4 05:20:54 CEST 2013

I am not seeing any good justification in your description for converting to matrix if you are planning to convert it back to data frame. Memory is going to be inefficiently-used if you do this.
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David Romano <dromano at stanford.edu> wrote:

>Hi everyone,
>I have large data frame, say df1,  with 165K columns, and all but the
>four columns of df1 are numeric.   I transformed the numeric data and
>obtained a matrix, call it data.m, with 165K - 4 columns, and then
>tried to
>create a second data frame by replacing the numeric columns of df1 by
>data.m.  I did this in two ways, and both ways instantly used up all
>available memory, so I was wondering whether there was a better way to
>Here's what I tried:
>df2 <- df1
>df2[ ,5:length(df1)] <- data.m
>df2 <- cbind( df1[1:4], data.m)
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