20.1.9  Classes

The classes command groups a collection of numbers into intervals.

• classes takes two or three arguments:
  • L, a list or matrix of numbers.
  • Optionally, a and b, numbers. (By default, these will be class_min and class_size from the graphics configuration, see Section 2.5.8, which themselves default to 0 and 1.)

    or:

  • Optionally, a and M, where a is the start of the beginning interval and M consists of the midpoints of the intervals.

    or:

  • Optionally, I, a list of intervals to use.
• classes(L,a,b) returns 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 n_k is how many numbers from L are in the corresponding interval.
• classes(L,a,M) returns a similar list, but instead of [[a..a+b,n₁],[a+b..a+2b,n₂],…], the intervals are determined by a and the list of midpoints M.
• classes(L,I) returns a similar list, but instead of [[a..a+b,n₁],[a+b..a+2b,n₂],…], the intervals are given by I. In this case, not every element of L is necessarily in an interval.

Examples