I have a data set that I have imported (not sure if that makes a
difference) and I would like to calculate the sum of only specific
columns.  I have tried
>colSums(dataset, by=list(dataset$col5), dims=1) and I get an error of
unused arguments
I have also tried
>aggregate(dataset, by=list(dataset$col5), sum) and I get the error that
sum is not meaningful for factors.

I want to only calculate the sum for specific columns because some of
the columns have words in them and I have not been able to find anything
else that would help or why these errors are occuring.
Jacquie

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