Aggregations & Math Functions

Aggregations reduce many values to fewer:

arr.sum(), arr.mean(), arr.min(), arr.max(), arr.std() np.median(arr), np.percentile(arr, 90)

On 2-D arrays, choose the axis: • no axis — one result for the whole array. • axis=0 — one result per column. • axis=1 — one result per row.

arr.argmax() and arr.argmin() return the position of the largest or smallest value instead of the value itself.