Calculates the median for each row (column) in a matrix

Calculates the median for each row (column) in a matrix.

rowMedians(x, rows = NULL, cols = NULL, na.rm = FALSE, dim. = dim(x),
  ..., useNames = TRUE)

colMedians(x, rows = NULL, cols = NULL, na.rm = FALSE, dim. = dim(x),
  ..., useNames = TRUE)

Arguments

x

An NxK matrix or, if dim. is specified, an N * K vector.

rows, cols

A vector indicating subset of rows (and/or columns) to operate over. If NULL, no subsetting is done.

na.rm

If TRUE, NAs are excluded first, otherwise not.

dim.

An integer vector of length two specifying the dimension of x, also when not a matrix.

...

Not used.

useNames

If TRUE (default), names attributes of the result are set, otherwise not.

Value

Returns a numeric vector of length N (K).

Details

The implementation of rowMedians() and colMedians() is optimized for both speed and memory. To avoid coercing to doubles (and hence memory allocation), there is a special implementation for integer matrices. That is, if x is an integer matrix, then rowMedians(as.double(x)) (rowMedians(as.double(x))) would require three times the memory of rowMedians(x) (colMedians(x)), but all this is avoided.

See also

See rowWeightedMedians() and colWeightedMedians() for weighted medians. For mean estimates, see rowMeans2() and rowMeans().

Author

Henrik Bengtsson, Harris Jaffee