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Transforming data frame

2016-02-10

1. melt()

This function comes from {reshape2} package. Can specify the id attribute so that those columns/variables are fixed.

Working example:

2. aggregate()

This function comes from {stats} package. Collapse data by defined function.

Working example:

aggregate(mpg ~ cyl, data = mtcars, mean)

##   cyl      mpg
## 1   4 26.66364
## 2   6 19.74286
## 3   8 15.10000

See also: Notes for {dplyr} package

3. cut()

Cut into different intervals; can specify labels.

Working example:

See also: Convert p-values using stars.pvals() and cut()

4. transform()

Add/change variable.

Working example: