Indexing and slicing in PyTorch - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select the first row of the tensor.

PyTorch

import torch
x = torch.tensor([[1, 2], [3, 4], [5, 6]])
first_row = x[1]

Drag options to blanks, or click blank then click option'

A[0]

B[1]

C[:, 0]

D[0, :]

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 1 instead of 0 to get the first row.

Using slicing syntax instead of indexing.

The first row of a tensor is accessed by using index 0 inside square brackets.

2fill in blank

medium

Complete the code to select the last column of the tensor.

PyTorch

import torch
x = torch.tensor([[1, 2, 3], [4, 5, 6]])
last_col = x[1]

Drag options to blanks, or click blank then click option'

A[0, -1]

B[-1, :]

C[:, -1]

D[:, 0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using row index -1 instead of column index -1.

Swapping row and column indices.

To select the last column, use ':' for all rows and '-1' for the last column index.

3fill in blank

hard

Fix the error in the code to correctly slice the tensor to get rows 1 and 2.

PyTorch

import torch
x = torch.tensor([[10, 20], [30, 40], [50, 60]])
subset = x[1]

Drag options to blanks, or click blank then click option'

A[1:2]

B[1, 3]

C[1;3]

D[1:3]

Attempts:

3 left

💡 Hint

Common Mistakes

Using a comma instead of colon in slicing.

Using incorrect stop index.

Slicing uses start:stop syntax, and stop is exclusive. To get rows 1 and 2, use 1:3.

4fill in blank

hard

Fill both blanks to select the middle column and rows 0 and 1.

PyTorch

import torch
x = torch.tensor([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
subset = x[1][2]

Drag options to blanks, or click blank then click option'

A[0:2]

B[1]

C[:, 1]

D[1:3]

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping row and column indices.

Using incorrect slice ranges.

Use [0:2] to select rows 0 and 1, and [:, 1] to select the middle column.

5fill in blank

hard

Fill all three blanks to create a tensor slice with rows 1 to 2 and columns 0 to 1.

PyTorch

import torch
x = torch.tensor([[5, 10, 15], [20, 25, 30], [35, 40, 45]])
subset = x[1][2][3]

Drag options to blanks, or click blank then click option'

A[1:3]

B[:, 0:2]

C[0:2]

D[:, 1:3]

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up row and column slices.

Using incorrect slice indices.

Use [1:3] to select rows 1 and 2, and [:, 0:2] to select columns 0 and 1.