Beyond map: The Workhorses

The methods that separate fluent Ruby from loops

Everyone knows map and select. The senior vocabulary is the aggregation and grouping set — reaching for the right one turns a ten-line loop into one expressive line. This lesson is a tour of the ones that earn their keep in real analytics code.

In an interview, say: "When I catch myself writing each with an accumulator outside the loop, that's a signal — the right method is usually each_with_object, inject, group_by, or tally. Naming the operation is clearer than hand-rolling the loop."