Kata

Taking a string as a phrase, find out how many letters are in each word and return this information in an array, in the form:

[[a0,a1],[b0,b1],...,[n0,n1]],

where the 0th index gives the word lengths and the 1st index gives the multiplicity within the string; e.g.,

[[1,7],...]

would signify seven occurences of one-letter words.

Ignore non-alphabet characters; sort array so information on shortest words come first.