R: Melt a data frame into form suitable for easy casting.

melt.data.frame {reshape2} | R Documentation

## Melt a data frame into form suitable for easy casting.

### Description

You need to tell melt which of your variables are id variables, and which are measured variables. If you only supply one of `id.vars` and `measure.vars`, melt will assume the remainder of the variables in the data set belong to the other. If you supply neither, melt will assume factor and character variables are id variables, and all others are measured.

### Usage

    ## S3 method for class 'data.frame'
    melt(data, id.vars, measure.vars,
      variable.name = "variable", ..., na.rm = FALSE, value.name = "value",
      factorsAsStrings = TRUE)

### Arguments

`data` | data frame to melt
`id.vars` | vector of id variables. Can be integer (variable position) or string (variable name). If blank, will use all non-measured variables.
`measure.vars` | vector of measured variables. Can be integer (variable position) or string (variable name)If blank, will use all non id.vars
`variable.name` | name of variable used to store measured variable names
`...` | further arguments passed to or from other methods.
`na.rm` | Should NA values be removed from the data set? This will convert explicit missings to implicit missings.
`value.name` | name of variable used to store values
`factorsAsStrings` | Control whether factors are converted to character when melted as measure variables. When `FALSE`, coercion is forced if levels are not identical across the `measure.vars`.

### See Also

`cast`

Other melt methods: `melt.array`, `melt.default`, `melt.list`

### Examples

    names(airquality) <- tolower(names(airquality))
    melt(airquality, id=c("month", "day"))
    names(ChickWeight) <- tolower(names(ChickWeight))
    melt(ChickWeight, id=2:4)

[Package reshape2 version 1.4.3 Index]