How do i merge a list into another list in python?
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Join Two ListsThere are several ways to join, or concatenate, two or more lists in Python. One of the easiest ways are by using the ExampleJoin two list: list1 = ["a", "b" , "c"] list3 = list1 + list2 Try it Yourself » Another way to join two lists are by appending all the items from list2 into list1, one by one: ExampleAppend list2 into list1: list1 = ["a", "b" , "c"] for x in list2: print(list1) Try it Yourself » Or you can use the ExampleUse the list1 = ["a", "b" , "c"] list1.extend(list2) Try it Yourself » In this tutorial, you’ll learn how to use Python to combine lists, including how to combine lists in many different ways. You’ll learn, for example, how to append two lists, combine lists sequentially, combine lists without duplicates, and more. Being able to work with Python lists is an incredibly important skill. Python lists are mutable objects meaning that they can be changed. They can also contain duplicate values and be ordered in different ways. Because Python lists are such frequent objects, being able to manipulate them in different ways is a helpful skill to advance in your Python career. The Quick Answer: Use the + Operator
The easiest way to combine Python lists is to use either list unpacking or the simple Let’s take a look at using the # Merge Two Lists list1 = ['datagy', 'is', 'a', 'site'] list2 = ['to', 'learn', 'python'] list3 = list1 + list2 print(list3) # Returns: ['datagy', 'is', 'a', 'site', 'to', 'learn', 'python'] We can see here that when we print out third list that it combines the first and second. Similarly, we can create a new list by unpacking all items from the lists we want to combine. By using the Let’s see what this would look like: # Merge Two Lists list1 = ['datagy', 'is', 'a', 'site'] list2 = ['to', 'learn', 'python'] list3 = [*list1, *list2] print(list3) # Returns: ['datagy', 'is', 'a', 'site', 'to', 'learn', 'python'] In the next section, you’ll learn how to combine two lists in Python in an alternating fashion, using the Python Want to learn more about Python f-strings? Check out my in-depth tutorial, which includes a step-by-step video to master Python f-strings! Combine Python Lists Alternating Using ZipWhen you combine Python lists, you may want to add items in an alternating method. For example, you may want to add the first item from both lists, then the second item, and so on. In order to this, we can use the Python Let’s see how we can use the # Merge Two Lists in Alternating Fashion list1 = ['1a', '2a', '3a'] list2 = ['1b', '2b', '3b'] list3 = [item for sublist in zip(list1, list2) for item in sublist] print(list3) # Returns: ['1a', '1b', '2a', '2b', '3a', '3b'] The We then use a list comprehension to flatten the zip object. To learn more about how this works, check out my tutorial on flattening lists of lists. In the next section, you’ll learn how to combine two Python lists without duplicates. Want to learn how to use the Python Combine Python Lists without DuplicatesPython lists allow us to have duplicate values in them – it’s one of the attributes that makes them special. Another Python data structure, a set, is similar to a list in some ways, but cannot have duplicate items. We can use the set to remove any duplicates from a list, by converting a list into a set. To learn more about removing duplicates from a Python list, check out my tutorial here. Let’s see how we can combine our lists and remove all duplicates by using a set: # Combine Python Lists without Duplicates list1 = [1, 2, 3, 4] list2 = [4, 5, 6, 7] list3 = list(set(list1 + list2)) print(list3) # Returns: [1, 2, 3, 4, 5, 6, 7] Let’s explore what we did here:
In the next section, you’ll learn how to concatenate arrays using Python. Need to automate renaming files? Check out this in-depth guide on using pathlib to rename files. More of a visual learner, the entire tutorial is also available as a video in the post! Python Concatenate Arrays
One of these methods is the Let’s see how we can use Python and # Concactenate Python Arrays import numpy as np list1 = [1,2,3] list2 = [4,5,6] array1 = np.array(list1) array2 = np.array(list2) array3 = np.concatenate((array1, array2.T)) print(array3) # Returns: [1 2 3 4 5 6] Let’s explore what we did here:
In the next section, you’ll learn how to combine Python lists using a for loop. Want to learn how to pretty print a JSON file using Python? Learn three different methods to accomplish this using this in-depth tutorial here. Combine Python Lists with a For LoopIn this section, you’ll learn how to use a for loop to append items from one list to another. While this isn’t really approach that’s necessary in most cases, it does give you flexibility in terms of what items to include. For example, using a for loop, you can skip certain items. Let’s take a look at two examples: (1) where you combine all items, and (2) where you combine conditionally: # Combine Two Python Lists with a For Loop list1 = ['datagy', 'is', 'a', 'site'] list2 = ['to', 'learn', 'python'] # Combine all items for item in list2: list1.append(item) print(list1) # Returns: ['datagy', 'is', 'a', 'site', 'to', 'learn', 'python'] # Combine items conditionally list1 = ['datagy', 'is', 'a', 'site'] list2 = ['to', 'learn', 'python'] for item in list2: if len(item) > 3: list1.append(item) print(list1) # Returns: ['datagy', 'is', 'a', 'site', 'learn', 'python'] Let’s explore what we did here in both examples:
In the next section, you’ll l earn how to use a Python list comprehension to combine lists in Python. Want to learn more about Python for-loops? Check out my in-depth tutorial that takes your from beginner to advanced for-loops user! Want to watch a video instead? Check out my YouTube tutorial here. Combine Python Lists with a List ComprehensionWe can also use a Python list comprehension to combine two lists in Python. This approach uses list comprehensions a little unconventionally: we really only use the list comprehension to loop over a list an append to another list. Let’s see what this looks like: # Combine Two Python Lists with a List Comprehension list1 = ['datagy', 'is', 'a', 'site'] list2 = ['to', 'learn', 'python'] [list1.append(item) for item in list2] print(list1) # Returns: ['datagy', 'is', 'a', 'site', 'to', 'learn', 'python'] The reason that this approach is a bit strange is that the comprehension floats by itself, acting more as a statement than the traditional assignment of a new list. Syntactically, this approach is strange and doesn’t server much purpose that is different from a for loop. In the next section, you’ll learn how to combine Python lists with only common elements. Want to learn more about Python list comprehensions? Check out this in-depth tutorial that covers off everything you need to know, with hands-on examples. More of a visual learner, check out my YouTube tutorial here. Combine Python Lists with Common ElementsThere may the times when you want to only combine common elements between two Python lists, meaning the intersection between the two lists. I have an in-depth tutorial on this topic here, which goes into great details around how this approach works. The approach shown below uses Let’s take a look at how to combine lists with only common elements: # Combine common elements between two lists list1 = [1, 2, 3, 4] list2 = [3, 4, 5, 6] list3 = list(set(list1).intersection(set(list2))) print(list3) # Returns: [3, 4] Let’s explore what we’ve done here:
In the next section, you’ll learn how to combine two lists using only unique elements across two lists. Check out some other Python tutorials on datagy, including our complete guide to styling Pandas and our comprehensive overview of Pivot Tables in Pandas! Combine Python Lists with Unique Elements OnlySimilar to the example above, you may want to combine two lists and only keep unique elements across the two lists. For this approach, we’ll again use sets, similar to the approach above, first checking for the intersection between two lists. Let’s see how we can do this in Python and then dive into how it works: # Combine unique elements between two lists list1 = [1, 2, 3, 4] list2 = [3, 4, 5, 6] common_elements = list(set(list1).intersection(set(list2))) combined = list1 + list2 for item in common_elements: combined = [element for element in combined if element != item] print(combined) # Returns: [1, 2, 5, 6] Let’s explore what we’ve done here:
The reason we use a list comprehension is that it allows us to check for duplicates. If we’d simply used a method, such as Want to learn how to use the Python ConclusionIn this post, you learned how to use Python to combine two lists. You learned how to do this by simply combining two lists in order. You also learned how to combine lists in alternating sequence and without duplicates. You also learned how to use for loops and list comprehensions to combine Python lists. Finally, you learned how to combine lists with only common elements and with only unique elements. To learn more about the Python list data structure, check out the official documentation here. How do I put multiple lists into one list?Using + operator
The + operator does a straight forward job of joining the lists together. We just apply the operator between the name of the lists and the final result is stored in the bigger list. The sequence of the elements in the lists are preserved.
How do you add two lists in Python?Method 1: Add two lists using the Naive Method:. # initialize the Python lists.. lt1 = [5, 10, 15, 20, 25, 30]. lt2 = [2, 4, 6, 8, 10, 12]. # print the original list element.. print ( " Python Original list 1: " + str (lt1)). print ( "Python Original list 2: " + str (lt2)). # use naive method to add two list.. How do I make a list in one list in Python?Practical Data Science using Python
There are different ways to flatten a list of lists. Straightforward way is to run two nested loops – outer loop gives one sublist of lists, and inner loop gives one element of sublist at a time. Each element is appended to flat list object.
How do you merge two lists without duplicates in Python?Use set() and list() to combine two lists while removing duplicates in the new list and keeping duplicates in original list. Call set(list_1) and set(list_2) to generate sets of the elements in list_1 and list_2 respectively which contain no duplicates.
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