| cut | R Documentation |
cut divides the range ofx into intervalsand codes the values inx according to whichinterval they fall. The leftmost interval corresponds to level one,the next leftmost to level two and so on.
cut(x, ...)## Default S3 method:cut(x, breaks, labels = NULL, include.lowest = FALSE, right = TRUE, dig.lab = 3, ordered_result = FALSE, ...)
x | a numeric vector which is to be converted to a factor by cutting. |
breaks | either a numeric vector of two or more unique cut points or asingle number (greater than or equal to 2) giving the number ofintervals into which |
labels | labels for the levels of the resulting category. By default,labels are constructed using |
include.lowest | logical, indicating if an ‘x[i]’ equal tothe lowest (or highest, for |
right | logical, indicating if the intervals should be closed onthe right (and open on the left) or vice versa. |
dig.lab | integer which is used when labels are not given. Itdetermines the number of digits used in formatting the break numbers. |
ordered_result | logical: should the result be an ordered factor? |
... | further arguments passed to or from other methods. |
Whenbreaks is specified as a single number, the range of thedata is divided intobreaks pieces of equal length, and thenthe outer limits are moved away by 0.1% of the range to ensure thatthe extreme values both fall within the break intervals. (Ifxis a constant vector, equal-length intervals are created, one ofwhich includes the single value.)
If alabels parameter is specified, its values are used to namethe factor levels. If none is specified, the factor level labels areconstructed as"(b1, b2]","(b2, b3]" etc. forright = TRUE and as"[b1, b2)", ... ifright = FALSE.In this case,dig.lab indicates the minimum number of digitsshould be used in formatting the numbersb1,b2, ....A larger value (up to 12) will be used if needed to distinguishbetween any pair of endpoints: if this fails labels such as"Range3" will be used. Formatting is done byformatC.
The default method will sort a numeric vector ofbreaks, butother methods are not required to andlabels will correspond tothe intervals after sorting.
As fromR 3.2.0,getOption("OutDec") is consulted when labelsare constructed forlabels = NULL.
Afactor is returned, unlesslabels = FALSE whichresults in an integer vector of level codes.
Values which fall outside the range ofbreaks are coded asNA, as areNaN andNA values.
Instead oftable(cut(x, br)),hist(x, br, plot = FALSE) ismore efficient and less memory hungry. Instead ofcut(*, labels = FALSE),findInterval() is more efficient.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)The New S Language.Wadsworth & Brooks/Cole.
split for splitting a variable according to a group factor;factor,tabulate,table,findInterval.
quantile for ways of choosing breaks of roughly equalcontent (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) #-- dummytx0 <- c(9, 4, 6, 5, 3, 10, 5, 3, 5)x <- rep(0:8, tx0)stopifnot(table(x) == tx0)table( cut(x, breaks = 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 0which(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" heretable(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_result = TRUE)## one way to extract the breakpointslabs <- levels(cut(aaa, 3))cbind(lower = as.numeric( sub("\\((.+),.*", "\\1", labs) ), upper = as.numeric( sub("[^,]*,([^]]*)\\]", "\\1", labs) ))Add the following code to your website.
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