Language Reference

The index creation operator (:) creates a row vector with a first element that is value1. The second element is value1+1, and so on, until the last element which is less than or equal to value2.

For example, the following statement creates the vector s which contains consecutive integers, shown in Figure 25.13:

s = 7:10;
print s;

If value1 is greater than value2, a reverse-order index is created. For example, the following statement creates the vector r which contains a decreasing sequence of integers, shown in Figure 25.14:

r = 10:6;
print r;

Neither value1 nor value2 is required to be an integer. Use the DO function if you want an increment other than 1 or .

The index creation operator also works on character arguments with a numeric suffix. For example, the following statements create a sequence of values that begin with the prefix "var", shown in Figure 25.15:

varList = "var1":"var5";
print varList;

Sequences of character values are often used to assign names to variables. You can use the string concatenation operator to dynamically determine the length of a sequence, as shown in the following statements:

x = {1 2 3 4,
     5 6 7 8,
     7 6 5 4};
numVar = ncol(x);                           /* 4 columns */
varNames = "X1":"X"+strip(char(numVar));    /* "X1":"X4" */
print x[colname=varNames];

Lastly, you can use the index operator to create a sequence of English letters, in either increasing or descending order, as follows:

a = "a":"h";
b = "P":"L";
print a, b;