subset.data.table

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Subsetting data.tables

Retruns subsets of a data.table.

Keywords
data
Usage
## S3 method for class 'data.table':
subset(x, subset, select, \ldots)
Arguments
x
data.table to subset.
subset
logical expression indicating elements or rows to keep
select
expression indicating columns to select from data.table
...
further arguments to be passed to or from other methods
Details

The subset argument works on the rows and will be evaluated in the data.table so columns can be referred to (by name) as variables in the expression. The data.table that is returned will maintain the original keys as long as they are not select-ed out.

Value

  • A data.table containing the subset of rows and columns that are selected.

See Also

subset

Aliases
  • subset.data.table
Examples
dt <- data.table(a=sample(c('a', 'b', 'c'), 20, replace=TRUE),
                 b=sample(c('a', 'b', 'c'), 20, replace=TRUE),
                 c=sample(20), key=c('a', 'b'))

sub <- subset(dt, a == 'a')
all.equal(key(sub), key(dt))
Documentation reproduced from package data.table, version 1.7.6, License: GPL (>= 2)

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