# How to filter for distinct values with pandas DataFrame\[\].unique()

In [Python pandas](https://www.ionos.ca/digitalguide/websites/web-development/python-pandas/), you can use the `unique()` function to **identify unique values in a column of a DataFrame**. This makes it easy to get a quick overview of the different values within your dataset.

## What is the syntax of pandas `DataFrame[].unique()`?

The basic syntax for using pandas `unique()` is simple. This is because the function doesn’t take any parameters:

```python
DataFrame['column_name'].unique()
```

Keep in mind that `unique()` can only be applied to **one column**. Before calling the function, you’ll need to indicate which column you want to evaluate. The `unique()` function returns a numpy array containing all the different values in the order they appear, with duplicate values in the column removed. It doesn’t, however, sort the values.

Note If you’ve been working with Python for a while, you may be familiar with the **numpy equivalent to pandas `unique()`**. For efficiency reasons, the pandas version is generally preferable.

## How to use pandas DataFrame\[\].unique()

To use `unique()` in a [pandas DataFrame](https://www.ionos.ca/digitalguide/websites/web-development/python-pandas-dataframe/), you need to first specify the column you want to check. In the following example, we’ll use a DataFrame that contains information about the age and city of residence of a group of individuals.

```python
import pandas as pd
# Create a sample DataFrame
data = {
    'Name': ['Alice', 'Bob', 'Charlie', 'David', 'Edward'],
    'Age': [24, 27, 22, 32, 29],
    'City': ['New York', 'Los Angeles', 'New York', 'Chicago', 'Los Angeles']
}
df = pd.DataFrame(data)
print(df)
```

The resulting DataFrame looks like this:

```none
Name  	Age       City
0    Alice    	24    New York
1    Bob   	27  	Los Angeles
2  Charlie    	22    	New York
3    David   	32    Chicago
4   Edward  	29  	Los Angeles
```

Now, let’s say we want to create a list of all the cities where the people in the DataFrame live. We can apply the pandas `unique()` function to the column that contains the cities.

```python
# Find different cities
unique_cities = df['City'].unique()
print(unique_cities)
```

The output is a **numpy array that lists each city once**, showing that the individuals in the DataFrame are from a total of three cities: New York, Los Angeles and Chicago.

```none
['New York' 'Los Angeles' 'Chicago']
```


This is a markdown version of: [https://www.ionos.ca/digitalguide/websites/web-development/python-pandas-dataframe-unique/](https://www.ionos.ca/digitalguide/websites/web-development/python-pandas-dataframe-unique/) for AI/LLM consumption.