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Miscellaneous fixes (#31587)

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* Miscellaneous fixes

Fix some errors in document, and changed some sentence structures.

* Restored title keyword

* Added missing word
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mail-liam
2019-04-06 22:48:01 +11:00
committed by The Coding Aviator
parent 1a20fbff6e
commit 177a014fdc
1 changed files with 7 additions and 7 deletions
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14
guide/english/python/lambda-expressions/index.md
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@@ -5,7 +5,7 @@ title: Lambda Expressions
Lambda Expressions are used when an operation only has to be performed once, meaning that there is no need for defining a function as it will not be used again. Lambda expressions also known as anonymous functions, as they are not named (defined).
Lambda functions can contain only one expression, so they are not best suited for functions with control-flow statements.
Lambda functions can contain only one expression, so they are not well suited for functions with control-flow statements.
#### Syntax of Lambda Function
`lambda arguments: expression`
@@ -21,11 +21,11 @@ print(square(3)) # Output: 9
# Traditional function to calculate square of a number
def square1(num):
return num ** 2
print(square(5)) # Output: 25
print(square1(5)) # Output: 25
```
In the above lambda example `lambda x: x ** 2` yields an anonymous function object which can be associated with any name.
So, we associated the function object with `square` and hence from now on we can call the `square` object like any traditional function. e.g. `square(10)`
So, we associated the function object with `square` and hence from now on we can call the object with `square` like any traditional function. e.g. `square(10)`
## Examples
@@ -57,7 +57,7 @@ print(res) # Output: 8
### Use-case
Let's say you want to filter out odd numbers from a `list`. You could use a `for` loop:
Say you want to filter out odd numbers from a `list`. You could use a `for` loop:
```python
my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
@@ -77,7 +77,7 @@ You could write this as a one-liner with list-comprehensions
filtered = [x for x in [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] if x % 2 != 0]
```
But you might be tempted to use the built-in `filter` function. Why? The first example is a bit to verbose, the one-liner can be harder to understand, where as `filter` offers the best of both words. What is more, the built-in functions are usually faster.
However, another option is to use the built-in `filter` function. Why? The first example is a bit to verbose, while the one-liner can be harder to understand. `filter` offers the best of both words, and the built-in functions are usually faster.
```python
my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
@@ -87,10 +87,10 @@ filtered = filter(lambda x: x % 2 != 0, my_list)
list(filtered)
# [1, 3, 5, 7, 9]
```
NOTE: in Python 3 built in function return generator objects, so you have to call `list`, while in Python 2 they return a `list`, `tuple`or `string`.
NOTE: In Python 3 built in functions return generator objects, so you have to call `list`, while in Python 2 they return a `list`, `tuple`or `string`.
What happened? You told `filter` to take each element in `my_list` and apply the lambda expressions. The values that return `False` are filtered out.
#### More Information:
- [Official Doc](https://docs.python.org/3/reference/expressions.html#lambda)
- [Further Read](https://dbader.org/blog/python-lambda-functions)
- [Further Reading](https://dbader.org/blog/python-lambda-functions)