> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sourcery.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Dictionary Comprehension

#### Sourcery refactoring id: `dict-comprehension`

#### Description:

Replaces dictionaries created with `for` loops with dictionary comprehensions

#### Before:

```python
cubes = {}
for i in range(100):
    cubes[i] = i**3
```

#### After:

```python
cubes = {x: x**3 for x in range(100)}
```

#### Explanation:

A dictionary comprehension can create the dictionary on one line, cutting out
the clutter of declaring an empty dict and then adding items.

Turning three lines of code into one is a definite win - it means less scrolling
back and forth when reading methods and helps keep things manageable.

Squeezing code onto one line can make it more difficult to read, but for
comprehensions this isn't the case. All of the elements that you need are nicely
presented, and once you are used to the syntax it is actually more readable than
the for loop version.

Another point is that the assignment is now more of an atomic operation - we're
declaring what `cubes` is rather than giving instructions on how to build it.
This makes the code read like more of a narrative, since going forward we will
care more about what `cubes` is than the details of its construction.

Finally comprehensions will usually execute more quickly than building the
collection in a loop, which is another factor if performance is a consideration.