plyr (version 1.4.1)

mutate: Mutate a data frame by adding new columns or replacing existing.

Description

Mutate a data frame by adding new columns or replacing existing.

Usage

mutate(.data, ...)

Arguments

.data

the data frame to transform

...

named parameters giving definitions of new columns.

Details

This function is very similar to transform but it executes the transformations iteratively so that later transformations can use the columns created by earlier transformations. Like transform, unnamed components are silently dropped.

Mutate seems to be considerably faster than transform for large data frames.

See Also

subset, summarise, arrange

Examples

# Examples from transform
mutate(airquality, Ozone = -Ozone)
mutate(airquality, new = -Ozone, Temp = (Temp - 32) / 1.8)

# Things transform can't do
mutate(airquality, Temp = (Temp - 32) / 1.8, OzT = Ozone / Temp) 

# mutate is rather faster than transform
system.time(transform(baseball, avg_ab = ab / g))
system.time(mutate(baseball, avg_ab = ab / g))