howto sort data

How can I sort by a certain column?

The class de.erichseifert.gral.data.DataTable offers a sort method which can be used to sort the stored data by one or more columns.

Given the following data:

DatTable data = new DataTable(Integer.class, Double.class, Double.class);
data.add(4, 1.0, 0.0);
data.add(3, 1.0, 1.0);
data.add(2, 1.0, 2.0);
data.add(1, 3.0, 3.0);

which produces the following data structure:

col 0	col 1	col 2
4	1.0	0.0
3	1.0	1.0
2	1.0	2.0
1	3.0	3.0

Single column

Sorting the data by the first column in ascending order

data.sort(new Ascending(0));

changes the data to

col 0	col 1	col 2
1	3.0	3.0
2	1.0	2.0
3	1.0	1.0
4	1.0	0.0

Sorting the data by the second column in descending order

data.sort(new Descending(1));

changes the data to

col 0	col 1	col 2
1	3.0	3.0
4	1.0	0.0
3	1.0	1.0
2	1.0	2.0

Multiple columns

Sorting the data by the second column in descending order and on equality sorting the data by the first column in ascending order.

data.sort(new Descending(1), new Ascending(0));

changes the data to

col 0	col 1	col 2
1	3.0	3.0
2	1.0	2.0
3	1.0	1.0
4	1.0	0.0

Sorting the data by the second column in descending order and on equality sorting the data by the third column in ascending order.

data.sort(new Descending(1), new Ascending(2));

changes the data to

col 0	col 1	col 2
1	3.0	3.0
4	1.0	0.0
3	1.0	1.0
2	1.0	2.0