The resulting plot shows that both methods are extremely fast for a few tens of thousands of elements. On the y axis, you can see the runtime in seconds needed to execute the respective functions. On the x axis, you can see the list size from 0 to 1,000,000 elements. Here’s the resulting plot that compares the runtime of the two methods append() vs extend(). In the third part of, you plot everything using the Python matplotlib library.In the second part, you compare the runtime of both functions using 100 different values for the list size n.In the first part, you define two functions list_by_append(n) and list_by_extend(n) that take as input argument an integer list size n and create lists of successively increasing integer elements using the append() and extend() methods, respectively.The code consists of three high-level parts: Plt.plot(extend_runtimes, extend_runtimes, label='extend()') Plt.plot(append_runtimes, append_runtimes, label='append()') List_sizes = Īppend_runtimes.append((size, time_1 - time_0))Įxtend_runtimes.append((size, time_2 - time_1))Īppend_runtimes = np.array(append_runtimes)Įxtend_runtimes = np.array(extend_runtimes) '''Creates a list & extends it with n elements''' '''Creates a list & appends n elements''' Here’s the code I used to measure and plot the results: which method is faster-append() or extend()? import time As elements, I simply incremented integer numbers by one starting from 0. Then, I created 100 lists with both methods, extend() and append(), with sizes ranging from 10,000 elements to 1,000,000 elements. I used my notebook with an Intel(R) Core(TM) i7-8565U 1.8GHz processor (with Turbo Boost up to 4.6 GHz) and 8 GB of RAM. My thesis is that the extend() method should be faster for larger list sizes because Python can append elements to a list in a batch rather than by calling the same method again and again. To answer this question, I’ve written a short script that tests the runtime performance of creating large lists of increasing sizes using the extend() and the append() methods. Instant PDF Download Which Method is Faster - extend() or append()? Click the image to download the high-resolution PDF file, print it, and post it to your office wall: Here’s your free PDF cheat sheet showing you all Python list methods on one simple page. Then, you use the extend method to add the three elements 3, 4, and 5 in a single call of the extend() method. (If you need a deeper understanding, check out my detailed article about the append() method on this blog.) In the code, you first add integer elements 1 and 2 to the list using two calls to the append() method. You can see this in the following example: > l = The difference between append() and extend() is that the former adds only one element and the latter adds a collection of elements to the list. The method list.extend(iter) adds all elements in iter to the end of the list.The method list.append(x) adds element x to the end of the list.If you want to learn how to append to a list using a while loop, visit Methods to Append to String in a Loop in Python.Here’s the short answer - append() vs extend(): Now that you know 4 methods to add more than one item to a list, you can decide which one you like best. # Append multiple items using list comprehension This method is like the append() method in a loop, but it uses an inline loop instead. List Comprehension is the last method in this tutorial for appending multiple items to a list. # Append multiple items using list concatenationĪs you can see, we've concatenated my_list with new_items using the + operator. With the list concatenation method, you can concatenate two lists, such as: my_list = This function takes an iterable (such as a list or tuple) as an argument and appends each item from the iterable to the list. We can also use the extend() function to append multiple items to a list. Use a for loop to iterate through each item in the new_items list.Īppend each item to my_list using append() inside the loop. ĭefine a new list called new_items with the items to add to my_list. let's see an example: my_list = ĭefine list called my_list containing the initial items. We can use the append() function in a loop to append multiple items to a list. Today, we'll look at 4 easy methods to add items to a Python list.
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