xy.group {Hmisc} | R Documentation

## Mean x vs. function of y in groups of x

### Description

Compute mean x vs. a function of y (e.g. median) by quantile groups of x or by x grouped to have a given average number of observations. Deletes NAs in x and y before doing computations.

### Usage

    xy.group(x, y, m=150, g, fun=mean, result="list")

### Arguments

`x` | a vector, may contain NAs
`y` | a vector of same length as x, may contain NAs
`m` | number of observations per group
`g` | number of quantile groups
`fun` | function of y such as median or mean (the default)
`result` | "list" (the default), or "matrix"

### Value

if result="list", a list with components x and y suitable for plotting. if result="matrix", matrix with rows corresponding to x-groups and columns named n, x, and y.

### See Also

`cut2`, `tapply`

### Examples

    # plot(xy.group(x, y, g=10))    #Plot mean y by deciles of x
    # xy.group(x, y, m=100, result="matrix")        #Print table, 100 obs/group

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