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12.8 SORT CASES

SORT CASES BY var_list[({D|A}] [ var_list[({D|A}] ] ...

SORT CASES sorts the active dataset by the values of one or more variables.

Specify BY and a list of variables to sort by. By default, variables are sorted in ascending order. To override sort order, specify (D) or (DOWN) after a list of variables to get descending order, or (A) or (UP) for ascending order. These apply to all the listed variables up until the preceding (A), (D), (UP) or (DOWN).

The sort algorithms used by SORT CASES are stable. This means records which have equal values of the sort variables have the same relative order before and after sorting. Thus, re-sorting an already sorted file does not affect the ordering of cases.

SORT CASES is a procedure. It causes the data to be read.

SORT CASES attempts to sort the entire active dataset in main memory. If workspace is exhausted, it falls back to a merge sort algorithm which creates numerous temporary files.

SORT CASES may not be specified following TEMPORARY.

12.8.1 Sorting Example

In Example 12.6 the data from the file physiology.sav is sorted by two variables, viz sex in descending order and temperature in ascending order. 

get file='physiology.sav'.
sort cases by sex (D) temperature(A).
list.

Example 12.6: Sorting cases by two variables.

In Results 12.4 you can see that all the cases with a sex of ‘1’ (female) appear before those with a sex of ‘0’ (male). This is because they have been sorted in descending order. Within each sex, the data is sorted on the temperature variable, this time in ascending order.

Data List
sex height weight temperature
1 1606 56.1 34.56
1 179 56.3 35.15
1 1609 55.4 35.46
1 1606 56.0 36.06
1 1607 56.3 36.26
1 1604 56.0 36.57
1 1604 56.6 36.81
1 1606 56.3 36.88
1 1604 57.8 37.32
1 1598 55.6 37.37
1 1607 55.9 37.84
1 1605 54.5 37.86
1 1603 56.1 38.80
1 1604 58.1 38.85
1 1605 57.7 38.98
1 1709 55.6 39.45
1 1604 -55.6 39.72
1 1601 55.9 39.90
0 1799 90.3 32.59
0 1799 89.0 33.61
0 1799 90.6 34.04
0 1801 90.5 34.42
0 1802 87.7 35.03
0 1793 90.1 35.11
0 1801 92.1 35.98
0 1800 89.5 36.10
0 1645 92.1 36.68
0 1698 90.2 36.94
0 1800 89.6 37.02
0 1800 88.9 37.03
0 1801 88.9 37.12
0 1799 90.4 37.33
0 1903 91.5 37.52
0 1799 90.9 37.53
0 1800 91.0 37.60
0 1799 90.4 37.68
0 1801 91.7 38.98
0 1801 90.9 39.03
0 1799 89.3 39.77
0 1884 88.6 39.97

Results 12.4: The physiology.sav file after sorting.

Note that SORT CASES, like all other transformations, affects only the active file. It does not have any effect upon the physiology.sav file itself. For that, you would have to rewrite the file using the SAVE command (see SAVE).

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