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Sorting Arrays using the VAR Command

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Sorting Arrays using the VAR Command

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Last UpdatedJan 08, 2024
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These facilities were designed to work with arrays of STRINGS.

Where a multi-level sort is required it is still necessary to use the older facilities of the VAR command to perform the sort. Using a different example, look at the arrays !Car, !Colour and !Year:

	!Car	!Colour	!Year
[1]	CHARIOT	MUD	26
[2]	FORD	RED	1978
[3]	VAUXHALL	YELLOW	1990
[4]	FORD	YELLOW	1993
[5]	FORD	(Unset)	1986
[6]	(Unset)	BLUE	1993
[7]	Ford	GREEN	(Unset)
[8]	(Unset)	(Unset)	(Unset)
[9]	vauxhall	YELLOW	1994
[10	FORD	YELLOW	1993

If you want to sort the arrays by car model, then on colour, and then on year, you would give the command:

VAR

!Index

SORT

!Car

CIASCII

!Colour

!Year

NUMERIC

The sorted index values are put into the array !Index, (for clarity shown here with the rows of the original arrays they are pointing to),

	!Index		!Car	!Colour	!Year
[1]	1	Þ	CHARIOT	MUD	2
[2]	7	Þ	Ford	GREEN	(Unset)
[3]	2	Þ	FORD	RED	1978
[4]	4	Þ	FORD	YELLOW	1993
[5]	10	Þ	FORD	YELLOW	1993
[6]	5	Þ	FORD	(Unset)	1986
[7]	3	Þ	VAUXHALL	YELLOW	1990
[8]	9	Þ	vauxhall	YELLOW	1994
[9]	6	Þ	(Unset)	BLUE	1993
[10	8	Þ	(Unset)	(Unset)	(Unset)

By default values are sorted ascending order using the ASCII character-codes. Other options which may be supplied after each array name are:

Sorting Option	Effect
CIASCII	Sorts in ascending case-independent alphabetic order.
DESCENDING	Sorts in alphabetic in reverse order
CIASCII DESCENDING	Sorts in descending case-independent alphabetic order.
NUMERIC	Forces an ascending numerical sort on numbers held as strings.
NUMERIC DESCENDING	Forces a descending numerical sort on numbers held as strings.

You can also modify the array to eliminate empty or repeated elements:

Option

Effect

UNIQUE

Eliminates instances of duplicated data. For example:

VAR !Index SORT UNIQUE !Car CIASCII !Colour !Year NUMERIC

!Index would then have only 9 elements as the value in the original row 10 was a second reference to a 1993 yellow Ford which is discarded.

NOUNSET

NOEMPTY

Eliminates rows that contain only UNSET values.

VAR !Index SORT NOUNSET !Car CIASCII !Colour !Year NUMERIC

Again !Index would have only 9 elements as the original row 8 is discarded.

The option NOEMPTY discards rows with values that are all blanks.

To sort these arrays and identify the last occurrence of each group of the same car type, use the LASTINGROUP option:

VAR

!Index

SORT

!Car

LASTINGROUP

!Group

This would create !Index by sorting the values in the array !Car , but would also would also create the array !Last:

	!Index	!Group		!Car
[1]	1	1	Þ	CHARIOT
[2]	2		Þ	FORD
[3]	4		Þ	FORD
[4]	5		Þ	FORD
[5]	10	2	Þ	FORD
[6]	3	3	Þ	VAUXHALL
[7]	7	4	Þ	ford
[8]	9	5	Þ	vauxhall
[9]	6		Þ	(Unset)
[10]	8	6	Þ	(Unset)

A similar option FIRSTINGROUP identifies the first row of each group.

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Sorting Arrays using the VAR Command

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Sorting Arrays using the VAR Command

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