# How to Find Index of Value in NumPy Array (With Examples)

You can use the following methods to find the index position of specific values in a NumPy array:

Method 1: Find All Index Positions of Value

```np.where(x==value)
```

Method 2: Find First Index Position of Value

`np.where(x==value)[0][0]`

Method 3: Find First Index Position of Several Values

```#define values of interest
vals = np.array([value1, value2, value3])

#find index location of first occurrence of each value of interest
sorter = np.argsort(x)
sorter[np.searchsorted(x, vals, sorter=sorter)]```

The following examples show how to use each method in practice.

### Method 1: Find All Index Positions of Value

The following code shows how to find every index position that is equal to a certain value in a NumPy array:

```import numpy as np

#define array of values
x = np.array([4, 7, 7, 7, 8, 8, 8])

#find all index positions where x is equal to 8
np.where(x==8)

(array([4, 5, 6]),)
```

From the output we can see that index positions 4, 5, and 6 are all equal to the value 8.

### Method 2: Find First Index Position of Value

The following code shows how to find the first index position that is equal to a certain value in a NumPy array:

```import numpy as np

#define array of values
x = np.array([4, 7, 7, 7, 8, 8, 8])

#find first index position where x is equal to 8
np.where(x==8)[0][0]

4
```

From the output we can see that the value 8 first occurs in index position 4.

### Method 3: Find First Index Position of Several Values

The following code shows how to find the first index position of several values in a NumPy array:

```import numpy as np

#define array of values
x = np.array([4, 7, 7, 7, 8, 8, 8])

#define values of interest
vals = np.array([4, 7, 8])

#find index location of first occurrence of each value of interest
sorter = np.argsort(x)
sorter[np.searchsorted(x, vals, sorter=sorter)]

array([0, 1, 4])
```

From the output we can see:

• The value 4 first occurs in index position 0.
• The value 7 first occurs in index position 1.
• The value 8 first occurs in index position 4.