# rank

The`rank`

filter is a numeric filter that takes a single set filter as argument:
rank a1 == 1 rank c3 == 3

If the set of squares represented by its argument contains a single square *s*, then the value of the
`rank`

filter is the numeric value of the rank of *s*.

If the set of squares represented by its argument does not contain exactly one single square, then the `rank`

filter does not match the current position.

The `rank`

filter is not affected by transform filters like flip or rotate90 .

# Examples

The`rank`

filter is used in averagedistance.cql, chameleon.cql, flipverticalecho.cql, horizontallysymmetric.cql, platzwechselecho.cql, platzwechseln2.cql .