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NumPy Array Search

Learn all about NumPy Array Search in this comprehensive tutorial.

5 min read intermediate
  • You can search an array for a certain value, and return the indexes that get a match.
  • There is a method called searchsorted() which performs a binary search in the array, and returns the index where the specified value would be inserted to maintain the search order.

Searching Arrays

You can search an array for a certain value, and return the indexes that get a match.

To search an array, use the where() method.

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The example above will return a tuple: (array([3, 5, 6],)

Which means that the value 4 is present at index 3, 5, and 6.

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Search Sorted

There is a method called searchsorted() which performs a binary search in the array, and returns the index where the specified value would be inserted to maintain the search order.

Note: The searchsorted() method is assumed to be used on sorted arrays.
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Example explained: The number 7 should be inserted on index 1 to remain the sort order.

The method starts the search from the left and returns the first index where the number 7 is no longer larger than the next value.

By default the left most index is returned, but we can give side='right' to return the right most index instead.

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Example explained: The number 7 should be inserted on index 2 to remain the sort order.

The method starts the search from the right and returns the first index where the number 7 is no longer less than the next value.

To search for more than one value, use an array with the specified values.

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The return value is an array: [1 2 3] containing the three indexes where 2, 4, 6 would be inserted in the original array to maintain the order.

Module quiz

2 questions
1

Which of the following is true about NumPy Array Search?

2

What is the most common pitfall when working with NumPy Array Search?

Answer all questions to submit.