Array attributes (shape, dtype, ndim, size) in NumPy - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of array shape and size

What is the output of the following code snippet?

NumPy

import numpy as np
arr = np.array([[1, 2, 3], [4, 5, 6]])
print(arr.shape, arr.size)

A (2, 3) 5

B (3, 2) 6

C (2, 3) 6

D (3, 2) 5

💡 Hint

Shape shows rows and columns; size is total elements.

The array has 2 rows and 3 columns, so shape is (2, 3). Total elements are 2*3=6.

❓ Predict Output

intermediate

Determine array data type

What will be printed by this code?

NumPy

import numpy as np
arr = np.array([1, 2, 3], dtype='float32')
print(arr.dtype)

A float32

B int32

C float64

D int64

💡 Hint

dtype shows the type of elements stored.

The array was created with dtype='float32', so arr.dtype is float32.

❓ data_output

advanced

Number of dimensions of an array

What is the value of arr.ndim after running this code?

NumPy

import numpy as np
arr = np.array([[[1, 2], [3, 4]], [[5, 6], [7, 8]]])
print(arr.ndim)

A 4

B 2

C 1

D 3

💡 Hint

Count how many levels of nested lists there are.

The array has 3 levels of nested lists, so ndim is 3.

❓ Predict Output

advanced

Shape and size of a reshaped array

What is the output of this code?

NumPy

import numpy as np
arr = np.arange(12)
arr = arr.reshape(3, 4)
print(arr.shape, arr.size)

A (3, 4) 12

B (4, 3) 12

C (3, 4) 11

D (4, 3) 11

💡 Hint

Reshape changes shape but size stays same.

The array is reshaped to 3 rows and 4 columns; size remains 12 elements.

🧠 Conceptual

expert

Understanding dtype impact on size

Given two arrays with the same shape but different dtypes, which statement is true?

A Both arrays have the same size attribute value.

B The array with larger dtype uses more memory but size attribute is same.

C The size attribute changes depending on dtype size in bytes.

D The array with smaller dtype has a larger size attribute.

💡 Hint

Size counts elements, not memory used.

Size counts number of elements, not memory. Memory depends on dtype but size attribute is element count.