It seems many programming languages have a function similar to
groupBy. Does anyone know whether there is a general mathematical name for this function? I.e., if
f is a function (in the set theory sense) mapping set X to Y, f inverse may not exist, but I certainly can pair every element
y in the range with the set of elements
x, in the domain which
f(x) = y.
groupBy(f) (for lack of better notation) maps
Y to the power set of
X, and is a well-defined function.
If I’m not mistaken, I believe such an operator also exists in relational algebra. Perhaps that name might be useful and evocative.
Does anyone know if this function has a name? I’m tempted to call it the