Routines (alphabetical) > Routines: M > MAKE_ARRAY

MAKE_ARRAY

The MAKE_ARRAY function enables you to dynamically create an array whose characteristics are not known until run time.

Syntax

Return Value

Returns an array of the specified type, dimensions, and initialization.

Arguments

D_i

Either an array or a series of scalar expressions specifying the dimensions of the result. If a single argument is specified, it can be either a scalar expression or an array of up to eight elements. If multiple arguments are specified, they must all be scalar expressions. Up to eight dimensions can be specified. If the dimension arguments are not integer values, IDL will convert them to integer values before creating the new array.

The D_iarguments are optional if the dimensions of the result are specified using the DIMENSION keyword. Note that you should supply either the D_i arguments or a value for the DIMENSION keyword, but not both.

Keywords

BYTE

Set this keyword to create a byte array.

COMPLEX

Set this keyword to create a complex, single-precision, floating-point array.

DCOMPLEX

Set this keyword to create a complex, double-precision, floating-point array.

DIMENSION

An array of up to eight scalar elements, specifying the dimensions of the result. Note that you should supply either the D_i arguments or a value for the DIMENSION keyword, but not both.

DOUBLE

Set this keyword to create a double-precision, floating-point array.

FLOAT

Set this keyword to create a single-precision, floating-point array.

L64

Set this keyword to create a 64-bit integer array.

INDEX

Set this keyword to initialize the array with each element set to the value of its one-dimensional subscript. This keyword cannot be used with arrays of objects or pointers.

INTEGER

Set this keyword to create an integer array.

LONG

Set this keyword to create a longword integer array.

NOZERO

Set this keyword to prevent the initialization of the array. Normally, each element of the resulting array is set to zero.

Note: This keyword is ignored for arrays of strings, objects, or pointers. Arrays of these types will always be initialized to zero.

OBJ

Set this keyword to create an object reference array.

PTR

Set this keyword to create a pointer array.

SIZE

A size vector specifying the type and dimensions of the result. The format of a size vector is given in the description of the SIZE function.

START

Set the START keyword to an integer giving the value of the first element in the array when the array is initialized by index. The default is 0. Setting this keyword is equivalent to adding a constant offset to each element of the result. This keyword is only applied if INDEX is set.

STRING

Set this keyword to create a string array.

TYPE

The type code to set the type of the result.

Type Code	Type Name	Data Type
0	UNDEFINED	Undefined
1	BYTE	Byte
2	INT	Integer
3	LONG	Longword integer
4	FLOAT	Floating point
5	DOUBLE	Double-precision floating
6	COMPLEX	Complex floating
7	STRING	String
8	STRUCT	Structure
9	DCOMPLEX	Double-precision complex
10	POINTER	Pointer
11	OBJREF	Object reference
12	UINT	Unsigned Integer
13	ULONG	Unsigned Longword Integer
14	LONG64	64-bit Integer
15	ULONG64	Unsigned 64-bit Integer

Note: All type code values except for TYPE=8 (structures) are valid. To create an array of structures, use the REPLICATE function.

UINT

Set this keyword to create an unsigned integer array.

UL64

Set this keyword to create an unsigned 64-bit integer array.

ULONG

Set this keyword to create an unsigned longword integer array.

VALUE

The value to initialize each element of the resulting array. VALUE can be a scalar of any type including structure types. The result type is taken from VALUE unless one of the other keywords that specify a type is also set. In that case, VALUE is converted to the type specified by the other keyword prior to initializing the resulting array.

Thread Pool Keywords

This routine is written to make use of IDL’s thread pool, which can increase execution speed on systems with multiple CPUs. The values stored in the !CPU system variable control whether IDL uses the thread pool for a given computation. In addition, you can use the thread pool keywords TPOOL_MAX_ELTS, TPOOL_MIN_ELTS, and TPOOL_NOTHREAD to override the defaults established by !CPU for a single invocation of this routine. See Thread Pool Keywords for details.

Examples

To create a 3-element by 4-element integer array with each element set to the value 5, enter:

M = MAKE_ARRAY(3, 4, /INTEGER, VALUE = 5)

Version History

4.0	Introduced
8.2.1	Added START keyword