# Add New Keys and Update Values in a Python Dictionary

> Add key-value pairs to a Python dictionary using square bracket assignment, the update method, dictionary unpacking, or the Python 3.9 update operator

**URL:** https://sentry.io/answers/python-dictionary-add-keys/

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## The Problem

How can I add new keys to a dictionary in Python?

## The Solution

Python provides a few different ways to add new key-value pairs to an existing dictionary. The simplest way is to assign a value to a new key using Python's indexing/square brackets syntax:

```python
prices = {"Apple": 1, "Orange": 2} # existing dictionary
prices["Avocado"] = 3 # new key-value pair

print(prices) # will print {"Apple": 1, "Orange": 2, "Avocado": 3}
```

This same syntax can be used to update existing key-value pairs:

```python
prices["Apple"] = 2

print(prices) # will print {"Apple": 2, "Orange": 2, "Avocado": 3}
```

To add and update multiple key-value pairs at once, we can use Python's [`dict.update()`](https://docs.python.org/3/builtins/stdtypes.html#dict.update) method:

```python
prices.update({"Pear": 2, "Grapefruit": 2, "Orange": 3}) # adds Pear and Grapefruit, and updates Orange

print(prices) # will print {"Apple": 2, "Orange": 3, "Avocado": 3, "Pear": 2, "Grapefruit": 2}
```

You can also use dictionary unpacking to merge dictionaries and add or update the key-value pairs:

```python
prices = {**prices, **{"Pear": 2, "Grapefruit": 2, "Orange": 3}}

print(prices) # will print {"Apple": 2, "Orange": 3, "Avocado": 3, "Pear": 2, "Grapefruit": 2}
```

As of [Python 3.9](https://docs.python.org/3/whatsnew/3.9.html), we can use the [update operator](https://peps.python.org/pep-0584/) (`|=`) instead of the `update()` method:

```python
prices |= {"Pear": 2, "Grapefruit": 2, "Orange": 3} # adds Pear and Grapefruit and updates Orange

print(prices) # will print {"Apple": 2, "Orange": 3, "Avocado": 3, "Pear": 2, "Grapefruit": 2}
```

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*Source: [sentry.io/answers/python-dictionary-add-keys/](https://sentry.io/answers/python-dictionary-add-keys/)*