Active November 29, 2021    /    Viewed 801    /    Comments 0    /    Edit

Examples of how to get the absolute value of a dataframe column in pandas:

### Create a dataframe with pandas

Let's create first a dataframe with pandas:

````import pandas as pd`
`import numpy as np`

`data = np.random.randint(-10,10, size=(5,4))`

`df = pd.DataFrame(data=data,columns=['a','b','c','d'])`
```

returns for example

````     a  b   c  d`
`0  1 -4   5 -3`
`1  4 -9  -4 -7`
`2 -7  6 -10  9`
`3  3 -5  -2  1`
`4  5 -5  -8  4`
```

### Apply abs() to one dataframe column

To get the absolute values over a dataframe column, a solution is to use pandas.DataFrame.abs :

````df = df['b'].abs()`
```

returns here

````     a  b   c  d`
`0  1 4   5 -3`
`1  4 9  -4 -7`
`2 -7  6 -10  9`
`3  3 5  -2  1`
`4  5 5  -8  4`
```

### Apply abs() to multiple dataframe columns

Note that abs() can be applied to multiple columns:

````cl = ['b','d']`

`df[ cl ] = df[ cl ].abs()`
```

returns

````     a  b   c  d`
`0  1  4   5  3`
`1  4  9  -4  7`
`2 -7  6 -10  9`
`3  3  5  -2  1`
`4  5  5  -8  4`
```

### Use abs() to filter the data

Another example on how to use abs() to filter the data:

````df['c'][ df['c'].abs() <= 5 ] = -999`
```

returns

````     a  b    c  d`
`0  1  4 -999  3`
`1  4  9 -999  7`
`2 -7  6  -10  9`
`3  3  5 -999  1`
`4  5  5   -8  4`
```

### References

##### Daidalos

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