Create an association by mapping a function over a list of keys:

Create an "inverted index" by swapping keys and values:

Use the operator form of AssociationMap:

As is standard for associations, if keys are repeated, later instances replace earlier ones:

When starting with an association, the application of the function can also produce repeated keys:

AssociationMap[f,{x₁,x₂,…}] creates an association with keys x_i:

The values in the association are given by Map[f,{x₁,x₂,…}]:

AssociationMap[f,{x₁,x₂,…}] is equivalent to AssociationThread[{x₁,x₂,…}Map[f,{x₁,x₂,…}]]:

AssociationMap[f,list] gives an association with the same length as DeleteDuplicates[list]:

AssociationMap maps a function over the rules in an association:

KeyValueMap maps a function over the keys and values in an association (and returns a list):

KeyMap maps a function over the keys in an association:

Map maps a function over the values in an association:

AssociationMap wraps an expression around the keys in a list:

AssociationComap wraps the keys in a list around an expression:

AssociationMap can be parallelized automatically:

AssociationMap[f,assoc] can return invalid associations if f does not return a rule: