R: Input a Covariance, Correlation, or Raw Moment Matrix

readMoments {sem} | R Documentation

## Input a Covariance, Correlation, or Raw Moment Matrix

### Description

This functions makes it simpler to input covariance, correlation, and raw-moment matrices to be analyzed by the `sem` function. The matrix is input in lower-triangular form on as many lines as is convenient, omitting the above-diagonal elements. The elements on the diagonal may also optionally be omitted, in which case they are taken to be 1.

### Usage

    readMoments(file="", text, diag=TRUE,
        names=as.character(paste("X", 1:n, sep = "")))

### Arguments

`file` | The (quoted) file from which to read the moment matrix, including the path to the file if it is not in the current directory. If `""` (the default) and the `text` argument is absent, then the moment matrix is read from the standard input stream, and is terminated by a blank line.
`text` | The moment matrix given as a character string, as an alternative to specifying the `file` argument or reading the moments from the input stream — e.g., when the session is not interactive and there is no standard input.
`diag` | If `TRUE` (the default), then the input matrix includes diagonal elements.
`names` | a character vector containing the names of the variables, to label the rows and columns of the moment matrix.

### Value

Returns a lower-triangular matrix (i.e., with zeroes above the main diagonal) suitable for input to `sem`.

### Author(s)

John Fox jfox@mcmaster.ca

### See Also

`sem`

### Examples

    R.DHP <- readMoments(diag=FALSE, names=c("ROccAsp", "REdAsp", "FOccAsp",
                    "FEdAsp", "RParAsp", "RIQ", "RSES", "FSES", "FIQ", "FParAsp"),
                    text="
        .6247
        .3269  .3669
        .4216  .3275  .6404
        .2137  .2742  .1124  .0839
        .4105  .4043  .2903  .2598  .1839
        .3240  .4047  .3054  .2786  .0489  .2220
        .2930  .2407  .4105  .3607  .0186  .1861  .2707
        .2995  .2863  .5191  .5007  .0782  .3355  .2302  .2950
        .0760  .0702  .2784  .1988  .1147  .1021  .0931 -.0438  .2087
    ")
    R.DHP

    #the following will work only in an interactive sessions:
        ## Not run:
    R.DHP <- readMoments(diag=FALSE, names=c("ROccAsp", "REdAsp", "FOccAsp",
                    "FEdAsp", "RParAsp", "RIQ", "RSES", "FSES", "FIQ", "FParAsp"))
        .6247
        .3269  .3669
        .4216  .3275  .6404
        .2137  .2742  .1124  .0839
        .4105  .4043  .2903  .2598  .1839
        .3240  .4047  .3054  .2786  .0489  .2220
        .2930  .2407  .4105  .3607  .0186  .1861  .2707
        .2995  .2863  .5191  .5007  .0782  .3355  .2302  .2950
        .0760  .0702  .2784  .1988  .1147  .1021  .0931 -.0438  .2087

    R.DHP

    ## End(Not run)

[Package sem version 3.1-13 Index]