How to get the number of the list in a list in Python 3?

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I am trying to get the number of the nested list that contains the particular number. This is my code:

listo = [[1,2],[3,4,5]]
for x in listo:
    if 3 in x:
       print(len(x))

What I am trying to get here is the number of the nested list that has 3 in it. My code is returning 3 because I am of the function len, which is only returning the number of items inside the nested list that has the number. The output should be:

2

Since the number 3 is located on the second nested list. The count starts from 1, not 0.

How can I get the proper output?

Use enumerate specifying the start value as 1:

listo = [[1,2],[3,4,5]]
for i, x in enumerate(listo, 1):
    if 3 in x:
        print(i)

# 2

How do I get the number of elements in a list?, The len() function can be used with several different types in Python - both built-in types and library types. For example: >>> len([1,2,3]) 3. Official 2.x  If you need to get the total number of elements in a list then use the len() function. The len function takes an argument that can be a list or other sequences like tuple, dict etc. As of our topic, for getting the total count of a list, the example below shows how you can do that:

Use enumerate:

listo = [[1,2], [3,4,5]]

res = next(i for i, sublist in enumerate(listo) if 3 in sublist)
print(res)  # -> 1

Note that Python is 0-index languange; the first element on a list has index number 0. That is why the code above returns 1. If you want to get 2, well, just add 1 to that or, ever better, use the optional start parameter of enumerate (enumerate(listo, 1)).

To make the above Error-proof1, you can specify a default value to be returned in case 3 is not on any sublist.

res = next((i for i, sublist in enumerate(listo) if 3 in sublist), 'N\A')

1 next raises StopIteration if it exhausts the iterable without finding something to return, unless a default value is provided.

Python, Given a list of lists, write a Python program to count the number of lists 3. Method #2 : Using type(). Use a for loop and in every iteration to check if the type of of kth column in List of Lists · Python | Get positive elements from given list of lists  This is very simple, because Python has a built-in function, len (), which is able to get the number of items in a list. So, say we have the following list, we get the following output. >>>>fruits= ['honeydew', 'cantaloupe', 'mango'] >>> len (fruits) 3 So all we have to do is use the len ()

Use enumerate so as to get the index of the element in the array.

l1 = ["eat","sleep","repeat"]

# printing the tuples in object directly
for ele in enumerate(l1):
    print ele

Output:
(0, 'eat')
(1, 'sleep')
(2, 'repeat')

The same can be used for the code above.

listo = [[1,2,3],[4,5]]
for ind,x in enumerate(listo):
     if 3 in x:
        print(ind)

Python 3 - List len() Method, Python 3 - List len() Method - The len() method returns the number of elements in the list. The integer 1 occurs in the list fish_ages 3 times, so when we use the .count() method, the number 3 is returned. list.sort() We can use the list.sort() method to sort the items in a list.

You can use enumerate. But if you are very new to coding this simple code is good.

Keep an extra variable (count) which will keep track of the index of the current list.

listo = [[1,2],[3,4,5]]
count = 0
for x in listo:
    count += 1
    if 3 in x:
        print(count)

Python 3 - Lists, Python 3 - Lists - The most basic data structure in Python is the sequence. Each element of a sequence is assigned a number - its position or index. In addition, Python has built-in functions for finding the length of a sequence and for finding  Varun September 7, 2019 Python : Get number of elements in a list, lists of lists or nested list 2019-09-07T09:27:28+05:30 List, Python No Comment In this article we will discuss different ways to count number of elements in a flat list, lists of lists or nested lists.

Simply use enumerate(). enumerate() returns a (element count, element) pair:

for count, element in enumerate(listo):
    if 3 in element:
        print(count + 1)
        # Account for one-based indexing

Python List count(), Join our newsletter for the latest updates. You have successfully subscribed to our newsletter. Join  Sometimes while coding in Python, you will need to take a list as an input. While this might sound simple at first, it is often regarded as a complex task to accomplish for a beginner. This article will tell you how to input a list in Python. Following pointers will be covered in this article, Input a List in Python

Lists - Learn Python 3, The negative index means we start at the last element and go left when reading a list. You can obtain the number of elements in a list with the function len  5.3. Tuples and Sequences ¶ We saw that lists and strings have many common properties, such as indexing and slicing operations. They are two examples of sequence data types (see Sequence Types — list, tuple, range ). Since Python is an evolving language, other sequence data types may be added. There is also another standard sequence data

11. Lists, The values that make up a list are called its elements, or its items. Since strings are immutable, Python optimizes resources by making two names that refer to for number in range(20): if number % 3 == 0: print(number) for fruit in ["banana",  Indexing Lists. Each item in a list corresponds to an index number, which is an integer value, starting with the index number 0. For the list sea_creatures, the index breakdown looks like this: The first item, the string 'shark' starts at index 0, and the list ends at index 4 with the item 'anemone'.

Lists and Tuples in Python – Real Python, You'll cover the important characteristics of lists and tuples in Python 3. You'll learn It doesn't make much sense to think of changing the value of an integer. List Comprehensions. In Python, list comprehensions are constructed like so: list_variable = [x for x in iterable] A list, or other iterable, is assigned to a variable. Additional variables that stand for items within the iterable are constructed around a for clause. The in keyword is used as it is in for loops, to iterate over the iterable.

Comments
  • enumerate(listo, 1) instead of i+1
  • this approach does not short-circuit. Add a break
  • @Ev.Kounis I don't think break is needed as OP is after finding positions of all sublists containing a 3.