Apply a Function to a Data Frame Split by Factors
Apply a Function to a Data Frame Split by Factors
By(x, INDICES, FUN, COLUMNS, array = FALSE, ...)
x |
Data frame |
INDICES |
Indices (vector or list of indices, vector of column names, or formula of column names) |
FUN |
A function to be applied to data frame subsets of 'data'. |
COLUMNS |
(Optional) subset of columns of x to work on |
array |
if TRUE an array/matrix is always returned |
... |
Additional arguments to lower-level functions |
Simple wrapper of the 'by' function
Klaus K. Holst
By(datasets::CO2,~Treatment+Type,colMeans,~conc) By(datasets::CO2,~Treatment+Type,colMeans,~conc+uptake)
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