pc1 {Hmisc} | R Documentation

## First Principal Component

### Description

Given a numeric matrix which may or may not contain `NA`s, `pc1` standardizes the columns to have mean 0 and variance 1 and computes the first principal component using `prcomp`. The proportion of variance explained by this component is printed, and so are the coefficients of the original (not scaled) variables. These coefficients may be applied to the raw data to obtain the first PC.

### Usage

    pc1(x, hi)

### Arguments

`x` | numeric matrix
`hi` | if specified, the first PC is scaled so that its maximum value is `hi` and its minimum value is zero

### Value

The vector of observations with the first PC. An attribute `"coef"` is attached to this vector. `"coef"` contains the raw-variable coefficients.

### Author(s)

Frank Harrell

### See Also

`prcomp`

### Examples

    set.seed(1)
    x1 <- rnorm(100)
    x2 <- x1 + rnorm(100)
    w <- pc1(cbind(x1,x2))
    attr(w,'coef')

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