The interval-vector is a vector whose elements list in succession the number of occurrences of each interval in an equal-temperament or one of its subsets, the elements ordered according to interval size from smallest to largest.
The diagram below represents 12-edo as a circle-of-degrees, with pink lines connecting each degree to form the circumference of the circle, and with other color-coded lines within the circle representing the interval-classes which can be found in the C-major scale used as the example. Legend:
|color||ic||standard interval names||frequency|
|black||ic 1||minor-2nd / major-7th||2|
|violet||ic 2||major-2nd / minor-7th||5|
|blue||ic 3||minor-3rd / major-6th||4|
|green||ic 4||major-3rd / minor-6th||3|
|yellow||ic 5||perfect-4th / perfect-5th||6|
|orange||ic 6||augmented-4th / diminished-5th||1|
It is only necessary to count the lines of each color to see the frequency of occurrence of each interval-class in the 12-edo C-major scale. The result is shown in the interval vector <254361>.