Idea: grouped calculations

[mayer79]

Hello HenRik

In base R, there is this wonderful function rowsum(). It calculates sums of all columns in a matrix, grouped by the unique values of a second argument. It is astonishingly fast. Have you ever thought of implementing something like rowsum, but for other statistics (mean, median, weighted mean, variance) etc.?

• grouped_rowmean()
• grouped_colmean()
• grouped_rowmedian()
• ...

?

[mayer79]

Just detected the "collapse" package from some (other) big names with this functionality (sum, mean, sd, var, count, cumsum, quantile, ...) with or without weights.

Will close this issue.