[Python] How to Find Element in List [exact match, partial match]

This article shows how to find element in list.

How to find an element by exact match and check if it is included in the list

To check if an element is included in list, the " in operator " is used.

If list contains an element, True is returned.

Here is an example code.

list_1 = ["Apple", "Banana", "Orange", "Bana", "Banana"]

print("App" in list_1)
# False
print("Apple" in list_1)
# True

Using "in operator", an element is searched by exact match.

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How to find an element by exact match and get index

To find an element by exact match and get index, the " index method " is used.

Here is an example code.

list_1 = ["Apple", "Banana", "Orange", "Bana", "Banana"]

print(list_1.index("Banana"))
# 1

As a supplement, here are two examples of the use of "index method".

How to avoid error stop when using "index method"

If a value not included in the list is specified, an error stop occurs.

list_1 = ["Apple", "Banana", "Orange", "Bana", "Banana"]

print(list_1.index("Ban"))
# 'Ban' is not in list

You can avoid the error stop by using the "in operator" as in the following code.

list_1 = ["Apple", "Banana", "Orange", "Bana", "Banana"]

search_value = "Ban"

if search_value in list_1 :
    print(list_1.index(search_value))
else :
    print("None")
# None

How to get the index of a duplicate element using the index method

The "index method" returns only the index of the first element if the list contains duplicate elements.

list_1 = ["Apple", "Banana", "Orange", "Bana", "Banana"]

print(list_1.index("Banana"))
# 1

In this sample code, there are two "bananas" in the list, but only the index "1" of the first element is returned.

Multiple indexes can be obtained by using "list comprehension" and "enumerate function".

◆List Comprehension

Here is how to write the list comprehension.

Extracts elements from the list for which " if statement" is True and returns a new list.

◆enumerate function

By using "enumerate function", the index and element are simultaneously extracted from a list.

Here is an example code to get the indexes of all duplicate elements in a list.

list_1 = ["Apple", "Banana", "Orange", "Bana", "Banana"]
print([i for i, x in enumerate(list_1) if x == 'Banana'])
# [1, 4]

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How to find elements by exact match and get the number of elements

To find elements by exact match and get the number of elements, the " count method " is used.

Here is an example code.

list_1 = ["Apple", "Banana", "Orange", "Bana", "Banana"]

print(list_1.count("Apple"))
# 1
print(list_1.count("Ban"))
# 0

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How to find an element of list by partial match

I show how to find an element of list by partial match.

Here is an example code.

list_1 = ["Apple", "Banana", "Orange", "Bana", "Banana"]

search_value = "Ban"
index_list = []

for i, e in enumerate(list_1) :
    if search_value in e :
        index_list.append(i)

print(index_list)
# [1, 3, 4]

A example code using list comprehension.

list_1 = ["Apple", "Banana", "Orange", "Bana", "Banana"]

search_value = "Ban"

print([i for i, x in enumerate(list_1) if search_value in x])
# [1, 3, 4]

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