Python append list in loop

How to Add Elements in List in Python Using For Loop

We will use the for loop to add elements to a list with the help of the Python append() method. Also, we will know how to add the elements to the empty and non-empty lists throughout this tutorial by covering the following topics.

• How to Add Elements in List in Python Using For Loop
• How to Add Elements in Empty List in Python Using For Loop

How to Add Elements in List in Python Using For Loop

We are going to use the Python append() method within the loop to add elements to the pre-defined non-empty list.

How to add elements in a list from another list in python using for loop

First, initialize the list which contains city names of the USA as a string using the below code.

usa_city = ["New York", "Los Angeles", "Chicago", "San Antonio"]

Create another list whose elements we will add to the above-created list “usa_city”.

append_usa_cty = ["Huston","Phoenix","Philadelphia"]

Define the for loop with the append() method to add the elements of “append_usa_cty” to “usa_city” list using the below code.

for i in range(len(append_usa_cty)): usa_city.append(append_usa_cty[i])

View the list “usa_city” to see the added elements from the list “append_usa_cty”.

This is how to add elements in a list from another list in python using for loop.

How to add elements in a list from user input in python using for loop

First, initialize the list which contains city names of the USA as a string using the below code.

usa_city = ["New York","Los Angeles","Chicago","San Antonio"]

Define a variable which is the number of city names we want to enter. For example, we will enter the value 2 for the below-defined variable because we are going to add the two city names in the list “usa_city”

num_city = int(input("Number of cities"))

Define the loop that will run till the number of city names we want to enter into the list or to the length of the variable “num_city”, each time loop will take an input or city name from the user using input() and add it to the list “usa_city” using the append() method.

for i in range(0, num_city): city_name = str(input()) usa_city.append(city_name) 

View the added city name of the USA using the below code.

Let’s understand what’s happening behind code numbers 11 and 12 in the above output:

• num_city = int(input(“Number of cities: “)) : The method input() accept input from the user and this entered input which is 2 is converted into integer because the method int(input()) is wrapped by the method int(). And then the value 2 is assigned to the variable num_city, Which means we want to add two city names to the list.
• for i in range(0, num_city): Then the loop begins and runs two times because the range of the loop is from 0 to 2 behind the scene.
• Within the loop there is code city_name = str(input()): This code accepts the city names and converts them into the string, then assign the string to the variable “city_name”. So we have entered two city names “Dallas” and “San Jose” one by one as the loop each time iterates.
• After, that there is another code in the loop usa_city.append(city_name): The append() method add the element to the list. So we provided the variable “city_name” to this method append(city_name) for adding the two city names to the list “usa_city” one by one as the loop each time iterates.

This is how to add the elements to the non-empty list from the user input or another list.

How to Add Elements in Empty List in Python Using For Loop

In the above subsection, we have learned how to add the elements in a non-empty list or a list that already contains some values in Python.

In this section, we will add the elements to the empty list, the procedure for adding the element to the empty list is the same as above, but here we will use the empty list instead of the non-empty list.

How to add elements in an empty list from another list in python using for loop

First, initialize the empty list which is going to contain the city names of the USA as a string using the below code.

Create another list whose elements we will add to the above-created empty list “usa_city”.

append_usa_cty = ["Huston","Phoenix","Philadelphia","New York","Los Angeles","Chicago","San Antonio"]

Define the for loop with the append() method to add the elements of “append_usa_cty” to the empty “usa_city” list using the below code.

for i in range(len(append_usa_cty)): usa_city.append(append_usa_cty[i])

View the list “usa_city” to see the added elements from the list “append_usa_cty”.

This is how to add elements in an empty list from another list in python using for loop.

How to add elements in an empty list from user input in python using for loop

First, initialize the empty list which is going to contain the city names of the USA as a string using the below code.

Create a variable for the number of city names to be entered. To add the three city names to the list “usa_city,” for instance, we will enter the value 3 for the variable below.

num_city = int(input("Number of cities"))

Define the loop that will run till the number of city names we want to enter into the list or to the length of the variable “num_city”, each time loop will take an input or city name from the user using input() and add it to the empty list “usa_city” using the append() method.

for i in range(0, num_city): city_name = str(input()) usa_city.append(city_name) 

View the added city name of the USA using the below code.

Let’s understand what’s happening behind code numbers 3 and 4 in the above output:

• num_city = int(input(“Number of cities: “)) : The method input() accept input from the user and this entered input which is 3 is converted into integer because the method int(input()) is wrapped by the method int(). And then the value 3 is assigned to the variable num_city, Which means we want to add three city names to the list.
• for i in range(0, num_city): Then the loop begins and runs two times because the range of the loop is from 0 to 3 behind the scene.
• Within the loop there is code city_name = str(input()): This code accepts the city names and converts them into the string, then assign the string to the variable “city_name”. So we have entered three city names “New York”, “San Jose”, and “Dallas” one by one as the loop each time iterates.
• After, that there is another code in the loop usa_city.append(city_name): The append() method add the element to the list. So we provided the variable “city_name” to this method append(city_name) for adding the two city names to the list “usa_city” one by one as the loop each time iterates.

This is how to add the elements to the empty list from the user input or another list in Python.

We have learned how to add the elements to pre-existing list from the user input or from another list. Also covered how to perform the addition of the elements to the empty or non-empty list by covering the following topics.

• How to Add Elements in List in Python Using For Loop
• How to Add Elements in Empty List in Python Using For Loop

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Python add to list in a loop | Appending elements in List example code

Use the append() method to add elements to a list while iterating over the list. Means you can add item in the list using loop and append method.

Example how to add to list in a loop in Python

Simple python example code.

Adding the number 0 to 4

The list append function does not return any value, it just adds the value to the list.

a = [] for i in range(5): a.append(i) print(a) 

Append elements to a list while iterating over the list

within the loop to add object to list while iterating over the list.

list1 = ["a", "b", "c"] list_length = len(list1) for i in range(list_length): list1.append("New " + list1[i]) print(list1)

Do comment if you have any doubts and suggestions on this Python list code.

Note: IDE: PyCharm 2021.3.3 (Community Edition)

Windows 10

Python 3.10.1

All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.

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