How to search in NumPy Arrays?

Searching Arrays in NumPy — how to find values, indexes, and conditions inside arrays.

1. `np.where()` — Find Indexes of Matching Values

This is the most common function used for searching.

Example: Find indexes of value 5

import numpy as np

arr = np.array([1, 5, 7, 5, 9])

result = np.where(arr == 5)
print(result)

Output:

(array([1, 3]),)

Indexes 1 and 3 contain value 5.

2. Search for Values Based on Condition

Example: Find all numbers greater than 6

print(np.where(arr > 6))

Output:

(array([2, 4]),)

3. Extract Elements Matching a Condition

Instead of indexes, get the elements directly:

print(arr[arr > 6])

Output:

[7 9]

4. Search in a 2D Array

arr2 = np.array([[1, 2, 3],
                 [4, 5, 6],
                 [7, 8, 9]])

# find where value is 5
print(np.where(arr2 == 5))

Output:

(array([1]), array([1]))

This means row 1, column 1.

5. `np.searchsorted()` — Searching Sorted Arrays

Used to find where a value should be inserted to keep an array sorted.

arr = np.array([10, 20, 30, 40])

print(np.searchsorted(arr, 25))

Output:

25 would go at index 1 to keep the array sorted.

Insert left or right position

print(np.searchsorted(arr, 30, side="right"))

Output:

6. Find All Non-zero Elements

arr = np.array([0, 3, 0, 4, 5])

print(np.nonzero(arr))

Output:

(array([1, 3, 4]),)

7. Check If Any / All Conditions Match

Check if any element matches condition:

print(np.any(arr > 4))

Output:

True

Check if all elements match:

print(np.all(arr > 0))

Output:

False

Summary Table

Function	Usage
`np.where()`	Find indexes matching a condition
`np.nonzero()`	Find all non-zero elements
`np.searchsorted()`	Find position in sorted array
`arr[condition]`	Get elements matching condition
`np.any()`	Checks if any condition is true
`np.all()`	Checks if all conditions are true

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How to search in NumPy Arrays?

Anubhav Kumar

Can you answer this question?

1 Answers

1. `np.where()` — Find Indexes of Matching Values

Example: Find indexes of value 5

2. Search for Values Based on Condition

Example: Find all numbers greater than 6

3. Extract Elements Matching a Condition

4. Search in a 2D Array

5. `np.searchsorted()` — Searching Sorted Arrays

Insert left or right position

6. Find All Non-zero Elements

7. Check If Any / All Conditions Match

Check if any element matches condition:

Check if all elements match:

Summary Table

Liked By

interview

How to search in NumPy Arrays?

Anubhav Kumar

Can you answer this question?

1 Answers

1. np.where() — Find Indexes of Matching Values

Example: Find indexes of value 5

2. Search for Values Based on Condition

Example: Find all numbers greater than 6

3. Extract Elements Matching a Condition

4. Search in a 2D Array

5. np.searchsorted() — Searching Sorted Arrays

Insert left or right position

6. Find All Non-zero Elements

7. Check If Any / All Conditions Match

Check if any element matches condition:

Check if all elements match:

Summary Table

Liked By

1. `np.where()` — Find Indexes of Matching Values

5. `np.searchsorted()` — Searching Sorted Arrays