Aggregation Functions (sum, mean, std, etc.)

NumPy includes built-in functions to quickly summarize data stored in arrays.

These let you calculate totals, averages, minimums, maximums, and more.

• np.sum(): total of all values
• np.mean(): average value
• np.min(): smallest value
• np.max(): largest value
• np.std(): standard deviation
• np.median(): middle value (helpful for distributions)

Aggregation functions can operate on the entire array or along a specific axis.

• axis=0: column-wise
• axis=1: row-wise

Copy
arr = np.array([[1, 2], [3, 4]])

print(arr.sum())           # Sum of all elements
print(arr.sum(axis=0))     # Sum down columns → [4 6]
print(arr.sum(axis=1))     # Sum across rows → [3 7]