np.cumsum() for cumulative sum in NumPy - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to calculate the cumulative sum of the array using numpy.

NumPy

import numpy as np
arr = np.array([1, 2, 3, 4])
cum_sum = np.[1](arr)
print(cum_sum)

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Acumsum

Bsum

Ccumprod

Dmean

Attempts:

3 left

💡 Hint

Common Mistakes

Using np.sum() which returns the total sum, not cumulative sums.

Using np.cumprod() which calculates cumulative product instead.

The np.cumsum() function calculates the cumulative sum of the elements in the array.

2fill in blank

medium

Complete the code to calculate the cumulative sum along axis 0 of the 2D array.

NumPy

import numpy as np
arr = np.array([[1, 2], [3, 4]])
cum_sum_axis0 = np.cumsum(arr, axis=[1])
print(cum_sum_axis0)

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A1

B0

C2

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using axis=1 which sums along columns instead of rows.

Using axis=2 which is invalid for 2D arrays.

Axis 0 means cumulative sum down the rows (along columns).

3fill in blank

hard

Fix the error in the code to correctly compute the cumulative sum of the list.

NumPy

import numpy as np
lst = [5, 10, 15]
cum_sum = np.cumsum([1])
print(cum_sum)

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Anp.array(lst)

Blst

Clist(lst)

Dnp.sum(lst)

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the list directly without conversion.

Using np.sum which returns total sum, not cumulative sums.

np.cumsum requires a numpy array or array-like. Converting list to np.array ensures correct operation.

4fill in blank

hard

Fill both blanks to create a dictionary with words as keys and their cumulative sum of lengths as values for words longer than 3 letters.

NumPy

words = ['apple', 'bat', 'carrot', 'dog']
cum_lengths = {word: [1] for word in words if len(word) [2] 3}
print(cum_lengths)

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Alen(word)

B>

C<=

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word itself as value instead of length.

Using wrong comparison operator like '<='.

We want lengths of words longer than 3 letters, so use len(word) and > operator.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase words as keys and their lengths as values for words longer than 3 letters.

NumPy

words = ['apple', 'bat', 'carrot', 'dog']
result = { [1]: [2] for word in words if len(word) [3] 3 }
print(result)

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Aword.upper()

Blen(word)

C>

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using original word as key instead of uppercase.

Using wrong comparison operator.

Swapping keys and values.

The dictionary keys are uppercase words, values are their lengths, filtered by length > 3.