R - Matrix Functions

Function Description
colSums ( X, na.rm = TRUE, dims = 1 ) Sums Column Values
rowSums ( X, na.rm = FALSE, dims = 1 ) Sums Row Values
   
colMeans ( X, na.rm = TRUE, dims = 1 ) Mean of the Column Values
rowMeans ( X, na.rm = FALSE, dims = 1 ) Mean of the Row Values
t ( matrix ) Transposes a matrix
na.rm = ( TRUE FALSE ) # Should missing values (including ~NaN) be omitted from the calculations?

dims - integer: Which dimensions are regarded as ‘rows’ or ‘columns’ to sum over. For row, the sum or mean is over dimensions dims+1, …; for col* it is over dimensions 1:dims.