Wolfram Language & System 10.3 (2015)|Legacy Documentation
Integrated into the Wolfram Language are powerful functions for analyzing large volumes of discrete and integer data—often conveniently specified using the Wolfram Language's uniquely flexible pattern language.
Differences — successive differences
Accumulate — cumulative sums
Union — unique elements in a single list or between lists
Tally — tally distinct elements, listing them with their multiplicities
Cases — list elements matching a pattern
Count — count elements matching a pattern
Position — positions of elements
list/.rule — replace elements according to a rule
ArrayRules — convert to sparse array form
FromDigits — convert to numbers, polynomials, etc.
ToString — convert to a string
FindSequenceFunction — find functional forms for integer sequences