Cara menggunakan update nested list python

Python List is one of the most important data structures. Python list can contain sub-list within itself too. That’s called a nested list.

While working with the python nested list, I came across some scenarios. I have shared those in this article. Like how to access the element, replace an element, count the occurrences of an element in the nested list, etc.

1. How to check if an element is present in a nested list?

Using any() function

any(elem in sub_list for sub_list in nested_list)

• If element present in the nested list returns True else returns False.

Using indexing

If we want to reverse the elements (sub_list) in the nested list, we can use the indexing method.

[element for element in sub_list for sub_list in nested_list]

Using [element for element in sub_list for sub_list in nested_list]1

[element for element in sub_list for sub_list in nested_list]

[element for element in sub_list for sub_list in nested_list]

How to reverse the elements in the sub-list?

Suppose, if we want to reverse the elements in the sub_list, then we have to iterate through the sub_list in the

[element for element in sub_list for sub_list in nested_list]

By using list comprehension, we can flatten the nested list. This is one way of doing it.

[element for element in sub_list for sub_list in nested_list]

• First, iterate through the nested list, then iterate through the sub_list and get each element.

Using [element for element in sub_list for sub_list in nested_list]9 method

First, iterate through the sublist in the nested list, then check if that particular element exists in that sub_list. If it exists, find the index of the sub_list and the index of the element in that sub_list.

Using List Comprehension

[(index1,index2) for (index1,sub_list) in enumerate(nested_list) 
for (index2,element) in enumerate(sub_list) if element==’X’]

• It will return a list of tuples containing index of that particular element.

for (index1,sub_list) in enumerate(nested_list)

[(index1,index2) for (index1,sub_list) in enumerate(nested_list) 
for (index2,element) in enumerate(sub_list) if element==’X’]

In the list, we can find the count of occurrences of an element using the

[(index1,index2) for (index1,sub_list) in enumerate(nested_list) 
for (index2,element) in enumerate(sub_list) if element==’X’]

l1.count()

In

[element for element in sub_list for sub_list in nested_list]

[(index1,index2) for (index1,sub_list) in enumerate(nested_list) 
for (index2,element) in enumerate(sub_list) if element==’X’]

Using remove() method

First, iterate through the

[(index1,index2) for (index1,sub_list) in enumerate(nested_list) 
for (index2,element) in enumerate(sub_list) if element==’X’]

for (index1,sub_list) in enumerate(nested_list)

It will remove all occurrences of that particular element from the nested list.

Using List Comprehension

Iterate through the nested list and then iterate through the sub_list and retain only the elements which don’t match the element to be removed.

If we want to insert an element at a particular index, we can do that by using the

for (index1,sub_list) in enumerate(nested_list)

Iterate through the sub_list in the

[element for element in sub_list for sub_list in nested_list]

sub_list.insert(index,element_to_inserted)

Get the index of the element which needs to be replaced and then assign the new element by mentioning the index:

my_list[index1][index2]=’X’

We can get the index of the sub_list and the index of that particular element from the sub_list using

for (index1,sub_list) in enumerate(nested_list)

Example 1

In the given nested list example, the first element in each sub_list is a key and the second element is the corresponding value.

First, we can iterate through the nested list and then assign the first element as a key and the second element as a value.

d[key]=value 
d[sub_list[0]]=sub_list[1]

Example 2

In the given nested list example, the first element in each sub_list is a key and the remaining elements are the corresponding value.

d[sub_list[0]]=sub_list[1:]

l1.count()

Example 1

In the below example, the first sub_list contains

l1.count()

Output:

Example 2

In the below example, all the sub_list contains the values. No column names in the sub_list.

Output:

Conclusion

In this article, I have covered some important tips on how to use nested lists in Python. Compared to regular Python lists, operations on nested lists are to be performed a little differently.