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 Language Reference

## SORT Call

sorts a matrix by specified columns

CALL SORT( matrix, by<, descend >)

The inputs to the SORT call are as follows:

matrix
is the input matrix, which is sorted in place by the call.
by
is either a numeric matrix of column numbers, or a character matrix containing the names of columns corresponding to column labels assigned to matrix by a MATTRIB statement or READ statement.
descend
is an optional matrix, indicating which columns, if any, should be descending order. Any by columns not specified as descending will be ascending. If descend = by, then all by columns will be descending; if descend is skipped or is a null matrix, then all by columns will be ascending.

The SORT call is used to sort a matrix, rearranging its rows according to the columns and order determined by the by and descend inputs. Because the sort is done in place, very little additional memory space is required. The SORT call is not as fast as the SORTNDX call for matrices with large rows. After a matrix has been sorted, the unique combinations of values in the by columns can be obtained from the UNIQUEBY function.

For example, the following statements produce the matrix , as shown:

```
m = { 1 1 0,
2 2 0,
1 1 1,
2 2 2};
call sort( m, {1 3}, {3} );
```

```
M

1         1         1
1         1         0
2         2         2
2         2         0
```

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