For loop: Below are the steps to create a list using for loop. If you want to learn more, Trey Hunner has many excellent articles and talks on this subject (for example, this one for beginners). If you closely look at [i**3 for i in range(1, 11)], you will find a for loop definition - for i in range(1, 11). list_name = [var for var in elements] List Comprehensions can use nested for loops. If this condition is True, then the expression num ** 2 is evaluated and appended to the list. Here’s a short piece of code that flattens a 2D list-res=[] for I in [[1,2,3],][2,3],[1]]: for j in i: res.append(j) The same task can be done much more efficiently by list comprehension with the line. The types are for and while. I could do. The value of the comprehension is the list. python documentation: List Comprehensions with Nested Loops. Take this function: >>> If the condition is True (which means if num is even), then num is appended to the list, otherwise it is not appended.Â. The ideal use case to apply it when you want to perform some operations on list elements. Inside [ ], we use a for loop which has a variable (i in the above example) for iteration. Even though list comprehensions are popular in Python, they have a specific use case: when you want to perform some operations on a list and return another list. You can often hear that list comprehension is “more Pythonic” (almost as if there was a scale for comparing how Pythonic something is, compared to something else ). Comparing this code to the syntax, num ** 2 is expression1, num ** 3 is expression2, num % 2 is condition and for num in range(1, 11) is for_loop. There are two types of loops are available in python. In the example above, the expression i * i is the square of the member value. The outer for loop is iterating over the elements of list1 and the inner for loop is iterating over the elements of list2. The following example creates a list containing all even numbers from 1 to 10 (included). Example: You want to create a list of all the fruits that has the letter "a" in the name. On each iteration of the for_loop, the expression is evaluated and defines the elements of the list. Many simple “for loops” in Python can be replaced with list comprehensions. Data Structures - List Comprehensions — Python 3.9.0 documentation 6. The values of i in the five iterations constitutes the five elements of the list mylist. Before learning Rest / Soap /GraphQL / you need to understand HTTP ! Comparing this syntax to the last example, num is expression, for i in range(1, 11) is for_loop and and if num % 2 == 0 is if condition. While, in this case, it’s not the best solution, an iterator is an excellent alternative to a list comprehension when we don’t need to have all the results at once. This sounds like a perfect use case for our problem, so let’s see how fast it will be. 2. Let’s see how much more space we’ll need to get the same result from the last example using a for loop. In each iteration, it is checked if the number is divisible by 2. It’s 133% slower than the list comprehension (104/44.5≈2.337) and 60% slower than the “for loop” (104/65.4≈1.590). List comprehension offers a shorter syntax when you want to create a new list based on the values of an existing list. In python, we can create List Comprehensions by using the following syntax: list_variable = [x for x in iterable] As you can see in List Comprehensions, a list is assigned to a variable. Say I want to create a list of numbers from 1 to 10. Is a smart and concise when compared to normal for loop every time a list comprehension is an data... Python list comprehension within another list comprehension within another list comprehension is 1 hence. Easy-To-Use data structure which is quite similar to nested for loops ” in Python can be rewritten list... Is already pretty simple to declare a list is created program as an example for if-else inside comprehensions. 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