R help - May 2013 - how to best add columns to a matrix with many columns

Hi everyone,

I have large data frame, say df1,  with 165K columns, and all but the first
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 the
available memory, so I was wondering whether there was a better way to do
this.

Here's what I tried:

df2 <- df1
df2[ ,5:length(df1)] <- data.m

and

df2 <- cbind( df1[1:4], data.m)

Thanks,
David

	[[alternative HTML version deleted]]

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
>first
>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
>the
>available memory, so I was wondering whether there was a better way to
>do
>this.
>
>Here's what I tried:
>
>df2 <- df1
>df2[ ,5:length(df1)] <- data.m
>
>and
>
>df2 <- cbind( df1[1:4], data.m)
>
>Thanks,
>David
>
>	[[alternative HTML version deleted]]
>
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