STANDARDIZE

The STANDARDIZE function computes standardized variables from an array of m variables (columns) and n observations (rows). The result is an m -column, n -row array where all columns have a mean of zero and a variance of one.

This routine is written in the IDL language. Its source code can be found in the file standardize.pro in the lib subdirectory of the IDL distribution.

Calling Sequence

Result = STANDARDIZE( A )

Argument

A

An m -column, n -row single- or double-precision floating-point array.

Keywords

DOUBLE

Set this keyword to force the computation to be done in double-precision arithmetic.

Example

Define an array with 4 variables and 20 observations.

array = $

[[19.5, 43.1, 29.1, 11.9], $

[24.7, 49.8, 28.2, 22.8], $

[30.7, 51.9, 37.0, 18.7], $

[29.8, 54.3, 31.1, 20.1], $

[19.1, 42.2, 30.9, 12.9], $

[25.6, 53.9, 23.7, 21.7], $

[31.4, 58.5, 27.6, 27.1], $

[27.9, 52.1, 30.6, 25.4], $

[22.1, 49.9, 23.2, 21.3], $

[25.5, 53.5, 24.8, 19.3], $

[31.1, 56.6, 30.0, 25.4], $

[30.4, 56.7, 28.3, 27.2], $

[18.7, 46.5, 23.0, 11.7], $

[19.7, 44.2, 28.6, 17.8], $

[14.6, 42.7, 21.3, 12.8], $

[29.5, 54.4, 30.1, 23.9], $

[27.7, 55.3, 25.7, 22.6], $

[30.2, 58.6, 24.6, 25.4], $

[22.7, 48.2, 27.1, 14.8], $

[25.2, 51.0, 27.5, 21.1]]

FOR K = 0, 3 DO PRINT, MOMENT(array[K,*])
; Compute the mean and variance of each variable using the MOMENT function. The skewness and kurtosis are also computed.

result = STANDARDIZE(array) ; Compute the standardized variables.

FOR K = 0, 3 DO PRINT, MOMENT(result[K,*])
; Compute the mean and variance of each standardized variable using the MOMENT function. The skewness and kurtosis are also computed.

IDL prints:

25.3050 25.2331 -0.454763 -1.10028

51.1700 27.4012 -0.356958 -1.19516

27.6200 13.3017 0.420289 0.104912

20.1950 26.0731 -0.363277 -1.24886

 

-7.67130e-07 1.00000 -0.454761    -1.10028

-3.65451e-07 1.00000 -0.356958    -1.19516

-1.66707e-07 1.00000 0.420290     0.104913

 4.21703e-07 1.00000 -0.363278    -1.24886

See Also

MOMENT