Assignment Operations and Arrays

The following table shows the variations possible in expressions containing array and scalar subscripts. The result of the assignment operation depends upon the dimensionality of the subscript.

Table 15-2: Introduction to Subscript Expression Structures

Table 15-2: Introduction to Subscript Expression Structures
Syntax Structure	Description
Variable[ScalarSubscripts] = ScalarExpression	Expression is stored in a single element of Variable. arrOne = [1, 2, 3, 4, 5] arrOne[2] = 9 PRINT, arrOne 1 2 9 4 5
Variable[ScalarSubscripts] = ArrayExpression	Expression array is inserted in Variable array beginning at point indicated by subscript. arrOne = [1, 2, 3, 4, 5] arrTwo = [11, 12] arrOne[1] = ArrTwo PRINT, arrOne 1 11 12 4 5 Note - An "out of range subscript" error will occur if you attempt to insert `arrTwo` elements into non-existent elements of `arrOne`. For example `arrOne[4] = ArrTwo` fails.
Variable[ArraySubscripts] = ScalarExpression	Expression scalar is stored in designated elements of Variable. Other array elements are unchanged. arrOne = [1, 2, 3, 4, 5] arrOne[[2, 4]] = 0 PRINT, arrOne 1 2 0 4 0 Note - Note the use of the double brackets. Attempting to assign zeros to the 3rd and 5th element of the array using `arrOne[2, 4] = 0` results in an error: "`Attempt to subscript ARRONE with <INT(4)> is out of range.`" IDL interprets this as attempting to modify a single element in the 3rd column and 5th row, which does not exist.
Variable[ArraySubscripts] = ArrayExpression	Elements of Expression are stored in designated elements of Variable. arrOne = [1, 2, 3, 4, 5] arrOne[[0, 2]] = [111,333] PRINT, arrOne 111 2 333 4 5 Note - Elements of the subscript array that are negative, or greater than the highest subscript of the subscripted array, are clipped to the target array boundaries. For example, `arrOne[[-1, 2]] = [111,333]`has the same result as `arrOne[[0,2]]`. See Clipping for details.