Converting between formats in SciPy - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to convert a dense matrix to a CSR sparse matrix.

SciPy

from scipy.sparse import csr_matrix
import numpy as np

dense_matrix = np.array([[1, 0, 0], [0, 2, 0], [0, 0, 3]])
sparse_matrix = csr_matrix([1])
print(sparse_matrix)

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Adense_matrix

Bcsr_matrix

Cnp.array

Dsparse_matrix

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the function name instead of the variable.

Passing the sparse matrix variable to itself.

Using np.array inside csr_matrix instead of the variable.

The csr_matrix function converts a dense numpy array into a CSR sparse matrix format.

2fill in blank

medium

Complete the code to convert a CSR sparse matrix back to a dense numpy array.

SciPy

from scipy.sparse import csr_matrix
import numpy as np

sparse_matrix = csr_matrix([[0, 0, 1], [1, 0, 0], [0, 2, 0]])
dense_matrix = sparse_matrix.[1]()
print(dense_matrix)

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Ato_numpy

Btodense

Ctoarray

Dtodense_array

Attempts:

3 left

💡 Hint

Common Mistakes

Using todense() which returns a matrix, not a numpy array.

Using a non-existent method like to_numpy().

Forgetting the parentheses after the method.

The toarray() method converts a sparse matrix to a dense numpy array.

3fill in blank

hard

Fix the error in the code to convert a COO sparse matrix to CSC format.

SciPy

from scipy.sparse import coo_matrix

row = [0, 3, 1, 0]
col = [0, 3, 1, 2]
data = [4, 5, 7, 9]
coo = coo_matrix((data, (row, col)), shape=(4, 4))
csc = coo.[1]()
print(csc)

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Atocsc

Btocsr

Ctoarray

Dtodense

Attempts:

3 left

💡 Hint

Common Mistakes

Using tocsr() which converts to CSR format instead.

Using toarray() or todense() which convert to dense formats.

Forgetting parentheses after the method.

The tocsc() method converts a COO sparse matrix to CSC format.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps each word to its length only if the length is greater than 3.

SciPy

words = ['data', 'is', 'fun', 'and', 'powerful']
lengths = {word: [1] for word in words if [2]
print(lengths)

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Alen(word)

Bword

Clen(word) > 3

Dword > 3

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word itself as the value instead of its length.

Checking if the word is greater than 3 instead of its length.

Omitting the condition or using incorrect syntax.

The dictionary comprehension maps each word to its length using len(word) only if the length is greater than 3, checked by len(word) > 3.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps each word in uppercase to its length only if the length is greater than 2.

SciPy

words = ['cat', 'a', 'dog', 'elephant']
result = { [1]: [2] for word in words if [3] }
print(result)

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Aword.upper()

Blen(word)

Clen(word) > 2

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word itself as the key instead of uppercase.

Using the word instead of length as the value.

Incorrect condition syntax or missing condition.

The dictionary comprehension maps each word in uppercase (word.upper()) to its length (len(word)) only if the length is greater than 2 (len(word) > 2).