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7.1.8  Classes: classes

The classes command can be used to groups a collection of numbers into intervals; the result will be a list where each element is an interval a..b followed by how many of the numbers are in the interval [a,b). The collection of numbers can be given as a list or matrix.

If L is a collection of numbers, a and b are numbers, then classes(L,a,b) will return the list [[a..a+b,n1],[a+b..a+2b,n2],...] where each number in L is in one of the intervals [a+kb, a+(k+1)b) and nk is how many numbers from L are in the corresponding interval. For example,


will return

[[0.0 .. 2.0,4],[2.0 .. 4.0,4],[4.0 .. 6.0,1]]



will return

[[(-1.0) .. 1.0,2],[1.0 .. 3.0,4],[3.0 .. 5.0,3]]

If the numbers a and b are omitted, they will default to the configurable values of class_min and class_size, which default to 0 and 1.

Another way to split the list L into intervals is by making the third argument the midpoints of the desired intervals. For example, if you enter


you will get


Finally, you can simply state the intervals that you want to use by giving them as a list for the second argument. In this case, not every number in the list is necessarily in one of the intervals. If you enter


you will get

[[1 .. 3,4],[3 .. 6,3]]

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