| subset {base} | R Documentation |
Return subsets of vectors or data frames which meet conditions.
subset(x, ...) ## Default S3 method: subset(x, subset, ...) ## S3 method for class 'data.frame': subset(x, subset, select, drop = FALSE, ...)
x |
object to be subsetted. |
subset |
logical expression. |
select |
expression, indicating columns to select from a data frame. |
drop |
passed on to [ indexing operator. |
... |
further arguments to be passed to or from other methods. |
For ordinary vectors, the result is simply
x[subset & !is.na(subset)].
For data frames, the subset argument works similarly on the
rows. Note that subset will be evaluated in the data frame, so
columns can be referred to (by name) as variables.
The select argument exists only for the method for data frames.
It works by
first replacing names in the selection expression with the
corresponding column numbers in the data frame and then using the
resulting integer vector to index the columns. This allows the use
of the standard indexing conventions so that for example ranges of
columns can be specified easily.
The drop argument is passed on to the indexing method for data
frames.
An object similar to x contain just the selected elements (for
a vector), rows and columns (for a data frame), and so on.
Peter Dalgaard
data(airquality) subset(airquality, Temp > 80, select = c(Ozone, Temp)) subset(airquality, Day == 1, select = -Temp) subset(airquality, select = Ozone:Wind) with(airquality, subset(Ozone, Temp > 80))