cut divides the range of
x into intervals and codes the values in
x according to which interval they fall. The leftmost interval corresponds to level one, the next leftmost to level two and so on.
cut(x, ...) ## S3 method for class 'default': cut((x, breaks, labels = NULL, include.lowest = FALSE, right = TRUE, dig.lab = 3, ordered_result = FALSE, ...))
- a numeric vector which is to be converted to a factor by cutting.
- either a numeric vector of two or more unique cut points or a single number (greater than or equal to 2) giving the number of intervals into which
xis to be cut.
- labels for the levels of the resulting category. By default, labels are constructed using
"(a,b]"interval notation. If
labels = FALSE, simple integer codes are returned instead of a factor.
- logical, indicating if an ‘x[i]’ equal to the lowest (or highest, for
right = FALSE) ‘breaks’ value should be included.
- logical, indicating if the intervals should be closed on the right (and open on the left) or vice versa.
- integer which is used when labels are not given. It determines the number of digits used in formatting the break numbers.
- logical: should the result be an ordered factor?
- further arguments passed to or from other methods.
breaks is specified as a single number, the range of the data is divided into
breaks pieces of equal length, and then the outer limits are moved away by 0.1% of the range to ensure that the extreme values both fall within the break intervals. (If
x is a constant vector, equal-length intervals are created, one of which includes the single value.)
labels parameter is specified, its values are used to name the factor levels. If none is specified, the factor level labels are constructed as
"(b2, b3]" etc. for
right = TRUE and as
"[b1, b2)", ... if
right = FALSE. In this case,
dig.lab indicates the minimum number of digits should be used in formatting the numbers
b2, .... A larger value (up to 12) will be used if needed to distinguish between any pair of endpoints: if this fails labels such as
"Range3" will be used.
The default method will sort a numeric vector of
breaks, but other methods are not required to and
labels will correspond to the intervals after sorting.
Values which fall outside the range of
breaks are coded as
NA, as are
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
quantile for ways of choosing breaks of roughly equal content (rather than length).
.bincode for a bare-bones version.
Z <- stats::rnorm(10000) table(cut(Z, breaks = -6:6)) sum(table(cut(Z, breaks = -6:6, labels = FALSE))) sum(graphics::hist(Z, breaks = -6:6, plot = FALSE)$counts) cut(rep(1,5), 4) #-- dummy tx0 <- c(9, 4, 6, 5, 3, 10, 5, 3, 5) x <- rep(0:8, tx0) stopifnot(table(x) == tx0) table( cut(x, b = 8)) table( cut(x, breaks = 3*(-2:5))) table( cut(x, breaks = 3*(-2:5), right = FALSE)) ##--- some values OUTSIDE the breaks : table(cx <- cut(x, breaks = 2*(0:4))) table(cxl <- cut(x, breaks = 2*(0:4), right = FALSE)) which(is.na(cx)); x[is.na(cx)] #-- the first 9 values 0 which(is.na(cxl)); x[is.na(cxl)] #-- the last 5 values 8 ## Label construction: y <- stats::rnorm(100) table(cut(y, breaks = pi/3*(-3:3))) table(cut(y, breaks = pi/3*(-3:3), dig.lab = 4)) table(cut(y, breaks = 1*(-3:3), dig.lab = 4)) # extra digits don't "harm" here table(cut(y, breaks = 1*(-3:3), right = FALSE)) #- the same, since no exact INT! ## sometimes the default dig.lab is not enough to be avoid confusion: aaa <- c(1,2,3,4,5,2,3,4,5,6,7) cut(aaa, 3) cut(aaa, 3, dig.lab = 4, ordered = TRUE) ## one way to extract the breakpoints labs <- levels(cut(aaa, 3)) cbind(lower = as.numeric( sub("\\((.+),.*", "\\1", labs) ), upper = as.numeric( sub("[^,]*,([^]]*)\\]", "\\1", labs) ))
Documentation reproduced from R 3.0.2. License: GPL-2.