# python intersection of two lists with code examples

Python provides several ways to find the intersection of two lists. In this article, we will discuss the most common methods for finding the intersection of two lists in Python.

Method 1: Using the '&' operator

The '&' operator can be used to find the intersection of two lists. The resulting list contains only the elements that are present in both lists. Here is an example:

```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

intersection = list1 & list2

print(intersection)
# Output: [4, 5]
```

Method 2: Using the 'intersection()' function

The 'intersection()' function can be used to find the intersection of two lists. The resulting list contains only the elements that are present in both lists. Here is an example:

```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

intersection = set(list1).intersection(list2)

print(intersection)
# Output: {4, 5}
```

Method 3: Using List comprehension

List comprehension can also be used to find the intersection of two lists. The resulting list contains only the elements that are present in both lists. Here is an example:

```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

intersection = [val for val in list1 if val in list2]

print(intersection)
# Output: [4, 5]
```

Method 4: Using 'filter' function

'filter' function can be used to find the intersection of two lists. The resulting list contains only the elements that are present in both lists. Here is an example:

```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

intersection = list(filter(lambda x: x in list1, list2))

print(intersection)
# Output: [4, 5]
```

In conclusion, there are several ways to find the intersection of two lists in Python, including the use of the '&' operator, the 'intersection()' function, list comprehension, and the 'filter' function. Each method has its own advantages and disadvantages, and the choice of method will depend on the specific requirements of the task at hand.

In addition to finding the intersection of two lists, there are several other related topics that are commonly used in Python programming.

1. Union of two lists: The union of two lists is a new list that contains all the elements from both lists, without any duplicates. This can be done using the '|' operator or the 'union()' function.
For example:
```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

union = set(list1) | set(list2)
print(union)
# Output: {1, 2, 3, 4, 5, 6, 7, 8}
```
1. Difference of two lists: The difference of two lists is a new list that contains all the elements that are present in the first list, but not in the second list. This can be done using the '-' operator or the 'difference()' function.
For example:
```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

difference = set(list1) - set(list2)
print(difference)
# Output: {1, 2, 3}
```
1. Symmetric difference of two lists: The symmetric difference of two lists is a new list that contains all the elements that are present in either of the two lists, but not in both. This can be done using the '^' operator or the 'symmetric_difference()' function.
For example:
```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

symmetric_difference = set(list1) ^ set(list2)
print(symmetric_difference)
# Output: {1, 2, 3, 6, 7, 8}
```
1. Subset and superset: A list can be checked if it is a subset or superset of another list. This can be done using the 'issubset()' and 'issuperset()' functions.
For example:
```list1 = [1, 2, 3, 4, 5]
list2 = [1, 2, 3]

print(set(list2).issubset(set(list1)))
# Output: True

print(set(list1).issuperset(set(list2)))
# Output: True
```

In conclusion, these topics are closely related to finding the intersection of two lists in Python and are commonly used in programming. Understanding these concepts can help you write more efficient and effective code.

## Popular questions

1. What is the syntax for finding the intersection of two lists in Python?

The syntax for finding the intersection of two lists in Python depends on the method being used. One of the most common methods is to use the '&' operator. The resulting list will contain only the elements that are present in both lists. Here is an example:

```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

intersection = list1 & list2

print(intersection)
# Output: [4, 5]
```
1. What is the difference between using the '&' operator and the 'intersection()' function to find the intersection of two lists in Python?

The '&' operator and the 'intersection()' function both return a set of elements that are common in both lists, but they are used in a slightly different way. The '&' operator is used to find the intersection of two lists directly, while the 'intersection()' function is used to find the intersection of two sets. In the case of lists, first, we need to convert lists to sets and then use the intersection() function.

```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

intersection = set(list1).intersection(list2)

print(intersection)
# Output: {4, 5}
```
1. Can the intersection of two lists be stored in a variable?

Yes, the intersection of two lists can be stored in a variable. The result of the intersection can be assigned to a variable, which can then be used for further processing or printing. Here's an example:

```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

intersection = list1 & list2

print(intersection)
# Output: [4, 5]
```
1. Can we find the intersection of two lists of different data types?

No, we can't find the intersection of two lists of different data types. The two lists must be of the same data type in order to find the intersection. For example, you can't find the intersection of a list of integers and a list of strings.

1. Can you give an example of how to find the intersection of two lists using list comprehension?

Yes, list comprehension can also be used to find the intersection of two lists. The resulting list contains only the elements that are present in both lists. Here is an example:

```list1 = [1, 2, 3, 4, 5]
list2 = [4, 5, 6, 7, 8]

intersection = [val for val in list1 if val in list2]

print(intersection)
# Output: [4, 5]
```

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