data.frame - how to calculate the number of rows
Hello, I had to give some more information to my posting: as ouput there are more than one row, depending on the values of column A (transformierung to distinct values, here 3 and 4, but there are much more)
A B C 1 3 6 5 2 3 4 20 3 3 8 2 4 4 8 3 5 4 2 6
Output:
A B C num rows 1 3 6 6.16 3 2 4 5 4.00 3
B is mean and C variance. thank you Macki
Hello,
it seems to be a simple problem, but I couldn't find an answer in the
archiv. (I think, it must has something to do with the group-select, like
in
php)
I've the following data.frame:
A B C
1 3 6 5
2 4 4 20
3 5 8 2
I want to get the number of the rows in the 4th column, like:
A B C num rows
1 3 6 6.16 3
(B is mean, C is variance by using summaryBy(B+C~ A, data=daten,
FUN=c(mean,var)) from the doBy-package)
But, how can I add the column 'numrow' and count the number of the rows?
Thanks!
Macki
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