sampleData

Purpose

Returns a sample of the rows of a matrix, chosen with or without replacement

Format

s = sampleData(x, size[, replace])
Parameters:
  • x (matrix) – population from which to take a sample
  • size (scalar) – the requested sample size
  • replace (scalar) – Optional argument, if replace is 0, the sample is drawn without replacement. If replace is 1, the sample is drawn with replacement. Default is 0.
Returns:

s (size x cols(x) matrix) – containing the sample taken from x.

Examples

Basic example without replacement

// Set seed for repeatable random draws
rndseed  23423;

// Create a 7x1 vector
x  = { 1,
       2,
       3,
       4,
       5,
       6,
       7 };

// Take a sample of 3 elements without replacement
s  = sampleData(x, 3);

After running the code above, s is equal to:

5
3
7

Basic example with replacement

// Set seed for repeatable random draws
rndseed  23423;

// Create a 7x2 vector
x  = { 1.2 1.8,
       2.7 2.1,
       3.0 3.3,
       4.8 4.1,
       5.1 5.4,
       6.0 2.8,
       7.2 3.9 };

replace = 1;

// Take a sample of 5 rows of 'x' with replacement
sample = sampleData(x, 5, replace);

After running the code above, sample is equal to:

5.1    5.4
3.0    3.3
6.0    2.8
4.8    4.1
3.0    3.3

Remarks

Indices for taking a random sample can be created with GAUSS function rndi().

The random number generator used in sampleData() to choose the samples is automatically seeded using the system clock when GAUSS first starts. However, that can be overridden using the rndseed statement.

See also

Functions rndi(), rndn(), rndseed()