| sweep {base} | R Documentation |
Sweep out Array Summaries
Description
Return an array obtained from an input array by sweeping out a summary statistic.
Usage
sweep(x, MARGIN, STATS, FUN = "-", check.margin = TRUE, ...)
Arguments
x |
an array, including a matrix. |
MARGIN |
a vector of indices giving the extent(s) of |
STATS |
the summary statistic which is to be swept out. |
FUN |
the function to be used to carry out the sweep. |
check.margin |
logical. If |
... |
optional arguments to |
Details
FUN is found by a call to match.fun. As in the
default, binary operators can be supplied if quoted or backquoted.
FUN should be a function of two arguments: it will be called
with arguments x and an array of the same dimensions generated
from STATS by aperm.
The consistency check among STATS, MARGIN and x
is stricter if STATS is an array than if it is a vector.
In the vector case, some kinds of recycling are allowed without a
warning. Use sweep(x, MARGIN, as.array(STATS)) if STATS
is a vector and you want to be warned if any recycling occurs.
Value
An array with the same shape as x, but with the summary
statistics swept out.
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
See Also
apply on which sweep used to be based;
scale for centering and scaling.
Examples
require(stats) # for median
med.att <- apply(attitude, 2, median)
sweep(data.matrix(attitude), 2, med.att) # subtract the column medians
## More sweeping:
A <- array(1:24, dim = 4:2)
## no warnings in normal use
sweep(A, 1, 5)
(A.min <- apply(A, 1, min)) # == 1:4
sweep(A, 1, A.min)
sweep(A, 1:2, apply(A, 1:2, median))
## warnings when mismatch
sweep(A, 1, 1:3) # STATS does not recycle
sweep(A, 1, 6:1) # STATS is longer
## exact recycling:
sweep(A, 1, 1:2) # no warning
sweep(A, 1, as.array(1:2)) # warning
## Using named dimnames
dimnames(A) <- list(fee=1:4, fie=1:3, fum=1:2)
mn_fum_fie <- apply(A, c("fum", "fie"), mean)
mn_fum_fie
sweep(A, c("fum", "fie"), mn_fum_fie)