Column-wise Aggregation
~10 mincode completion
Implement column_sums(X) that returns the sum of each column.
Examples
2x3 matrix column sums
- Input
- column_sums([[1, 2, 3], [4, 5, 6]])
- Output
- [5, 7, 9]
3x2 matrix column sums
- Input
- column_sums([[10, 20], [30, 40], [50, 60]])
- Output
- [90, 120]
Cancelling values give zero
- Input
- column_sums([[1, 0], [-1, 0]])
- Output
- [0, 0]
Hints
Hint 1
The reduction runs down the columns, so pass .
Hint 2
Reach for 0 rather than axis 1.
Requirements
X: 2D array of shape (m, n)Return 1D array of shape (n,) containing the sum of each column.
Use a fully vectorised implementation without Python loops
Constraints
Vectorised implementation only, no Python loops
Allowed library: NumPy only
Time limit: 200 ms, Memory: 64 MB
Try similar problems(4)
Where this shows up
~10 min
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Python
import numpy as np
def column_sums(X: np.ndarray) -> np.ndarray:
"""
Return the sum of each column.
Args:
X: 2D array of shape (m, n)
Returns:
1D array of shape (n,) containing the sum of each column.
"""
# YOUR CODE HERE
pass