Convert Data to Numeric Values by Constructing Dummy Variables

Description

Converts data of any kind to numeric values. A factor is expanded to a set of dummy variables.

Usage

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Arguments

x

Vector, factor, matrix or data frame to be converted.

Details

This function converts data (such as a factor) to numeric values in order that the user may calculate, for example, the mean, variance, covariance and correlation of the data.

If x is a numeric vector or integer vector, it is returned unchanged.

If x is a logical vector, it is converted to a 0-1 matrix with 2 columns. The first column contains a 1 if the logical value is FALSE, and the second column contains a 1 if the logical value is TRUE.

If x is a complex vector, it is converted to a matrix with 2 columns, containing the real and imaginary parts.

If x is a factor, the result is a matrix of 0-1 dummy variables. The matrix has one column for each possible level of the factor. The (i,j) entry is equal to 1 when the ith factor value equals the jth level, and is equal to 0 otherwise.

If x is a matrix or data frame, the appropriate conversion is applied to each column of x.

Note that, unlike model.matrix, this command converts a factor into a full set of dummy variables (one column for each level of the factor).

Value

A numeric matrix.

Author(s)

\adrian

Examples

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   chara <- sample(letters[1:3], 8, replace=TRUE)
   logi <- (runif(8) < 0.3)
   comp <- round(4*runif(8) + 3*runif(8) * 1i, 1)
   nume <- 8:1 + 0.1
   df <- data.frame(nume, chara, logi, comp)
   df
   dummify(df)

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