How to determine chain length on a Brompton? Running the above code returns this list of the elements and their indexes: Pythons lambda function is an anonymous function in which a mathematical expression is evaluated and then returned. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. You learned how to use a for loop, a while loop, and a list comprehension. That said, its a commonly used method to iterate over a Python list while accessing both the index and the item. To learn more, see our tips on writing great answers. In Python, lists can be used to store multiple elements in a single variable. A Guide to Iterating Over a List in Python, How to Loop Over a List in Python with a For Loop, How to Loop Over a List in Python with a While Loop, How to Loop Over a List in Python with a List Comprehension, How to Iterate Over a List with Index Items Using Range, How to Iterate Over a List with enumerate, How to Iterate Over Multiple Python Lists Element-Wise, How to Iterate Over and Manipulate Python Lists, check out my complete tutorial on list comprehensions, Python map Function: Transforming Iterables without Loops, Python enumerate: Python Looping with Index Counters. In Python, the list is a type of container in Data Structures, which is used to store multiple data at the same time. We can loop through a list in Python using the 8 different methods. Check out my profile. To learn more, see our tips on writing great answers. In the above example, we first imported itertools. One of the basic ways to iterate or loop through a list is by using the for loop in Python. Example #1: Using simple iteration and range () Python3 string_name = "geeksforgeeks" for element in string_name: print(element, end=' ') print("\n") string_name = "GEEKS" (Tenured faculty). What's happening is that in for i in fruit[l][1], you are iterating over every character in the second string in every sub-list. Iterate Through List in Python Using Itertool.Cycle11. Example: how to iterate over a list in python # Python list my_list = [ 1 , 2 , 3 ] # Python automatically create an item for you in the for loop for item in my_list : print ( item ) Tags: Print all items by referring to their index number: The iterable created in the example above is [0, 1, 2]. Strings are iterable in Python. Remember to increase the index by 1 after each iteration. Iterate Through List in Python Using While Loop 3. list1.remove(i) The first item has an index of 0, the second list item is 1, and so on.) All Rights Reserved. Using normal for loop syntax can automatically iterates from start to end. The repeated execution of several groups of code statements within a program is known as iteration. A for loop allows you to iterate over an interable object (like a list) and perform a given action. In the code below, that condition is the length of the list; the i counter is set to zero, then it adds 1 every time the loop prints one item in the list. Create list of strings. Default is 0. And it is more pythonic to iterate by value, not by index. Python - How to Iterate over nested dictionary ? The suggestion that using range(len()) is the equivalent of using enumerate() is incorrect. But, instead of assessing each string it is assessing each character of each string here is what i mean: Really I would like to take some action with each string. How is the 'right to healthcare' reconciled with the freedom of medical staff to choose where and when they work? So Lets directly come to the point and begin the journey. And how to capitalize on that? The list contains six elements in it which are [9, 11, 13, 15, 17, 19] respectively. Simple example codes multiple ways to iterate over a list in Python. We know that for loop in Python is used to iterate over a sequence or other iterable objects. len() functions to create a suitable iterable. Required fields are marked *. A number specifying at which position to stop (not included). So I am not demonstrating about for loops here. Do comment if you have any doubts or suggestions on this Python Iterate list topic. I will simplify it here. There may be times that you want to iterate over a list by accessing both the item and the index of the item. print(list1), I expect to see this result: When Tom Bombadil made the One Ring disappear, did he put it into a place that only he had access to? This is a typical list iteration problem in Python. The list contains seven elements in it. How to concatenate (join) items in a list to a single string, How to iterate over rows in a DataFrame in Pandas. Optional. And thats what well explain in this article. Method 1: Using For loop We can iterate over a list in Python by using a simple For loop. Is there no one function that will iterate over a list of strings or strings and integers and populate a dictionary like so: {list[0] : list[1] list[2] : list[3] list[4] : list [5]} I've seen 40 different ways of doing it that are more complicated than if there was just one function that did it. - user707650 Jan 7, 2014 at 10:18 1 Ways to Iterate Through List in Python In this tutorial we will discuss in detail all the 11 ways to iterate through list in python which are as follows: 1. Grouper is function which we can use to group the elements of list and iterate through them. Plus, there arent many tricky questions, and you will always be able to count on help and hints. So if you make it till the end, I am pretty sure you now be able to understand all the possible ways to iterate through the list in Python. If you need the index sometime, try using enumerate: The -1 in word[-1] above is Python's way of saying "the last element". A FOR loop in Python is a powerful iteration construct that allows you to loop through a sequence of values, such as a list or a string, and perform a set of rjacademy - Professional Development Lab sur LinkedIn : From Zero to Hero with Python's FOR Loop: A Comprehensive Tutorial. Python For Loops A for loop is used for iterating over a sequence (that is either a list, a tuple, a dictionary, a set, or a string). Join our monthly newsletter to be notified about the latest posts. A for loop in Python is a control flow statement used to iterate over a sequence (such as a list, tuple, string, or range object) and execute a block of code. In this article, we are going to see how to iterate through a nested List. Use the len () function to determine the length of the list, then start at 0 and loop your way through the list items by referring to their indexes. To work effectively with Python, you need to know the functions and methods that work with lists. Makes complete sense now. Example 1: Iteration by while loop for a condition. Note: Remember to unpack the element using * because zip_longest returns iterator of tuples. It returns an iterator that yields pairs consisting of the index and the item at that index. A-143, 9th Floor, Sovereign Corporate Tower, We use cookies to ensure you have the best browsing experience on our website. In this example we will iterate a 2d array using numpy module. Here lambda y:y is provided as input function and n is the second argument to the map() function. Here the iterable can be a list,tuple,string,etc. Suppose you have large single-dimensional lists with a single data type. Hello fellow programmers in todays article we will learn how to iterate through the list in Python. I'm trying to split the elements of a list: builtins.AttributeError: 'list' object has no attribute 'split'. [4,5] You can leverage enumerate() function to get index every iteration and use that index to loop through list. You can use for index, row in df.iterrows(): to iterate over dataframe. List Comprehension offers the shortest syntax for looping through lists: A short hand for loop that will print all items in a list: Learn more about list comprehension in the next chapter: Iterate Through List in Python Using For Loop 2. With the help of the lambda function, we can take n number of arguments, but there will be only one expression. But that list actually is a list of key/value pairs, and we are asking for each key and value from a single source -- rather than from two lists (like we did above). acknowledge that you have read and understood our, Data Structure & Algorithm Classes (Live), Data Structures & Algorithms in JavaScript, Data Structure & Algorithm-Self Paced(C++/JAVA), Full Stack Development with React & Node JS(Live), Android App Development with Kotlin(Live), Python Backend Development with Django(Live), DevOps Engineering - Planning to Production, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, Important differences between Python 2.x and Python 3.x with examples, Statement, Indentation and Comment in Python, How to assign values to variables in Python and other languages, Adding new column to existing DataFrame in Pandas, How to get column names in Pandas dataframe, Python program to convert a list to string, Reading and Writing to text files in Python, Different ways to create Pandas Dataframe. Iterate Through List in Python Using Numpy Module 4. Iterators are generally implemented within loops, comprehensions, generators, etc. If yes there is an awesome tutorial available in our library of tutorials do check it out. Theyre also heterogeneous, meaning that they can hold many different data types. Each integer is passed in a single iteration; the append() function saves it to lst2. The methods weve discussed so far used a small lists. List comprehension is similar to the for loop; however, it allows us to create a list and iterate through it in a single line. The parameters of zipping () function, in this case, are (num, daypart) and they will be aggregated together. Python. Your email address will not be published. Python Nested for Loop In Python, the for loop is used to iterate over a sequence such as a list, string, tuple If you want to practice what youve learned (and solidify your understanding of Python) check out our Python Practice Set. Python iterate through a list and append to a string; Python add to . []. Iterate Through List in Python Using zip()10. for i in list1: In Python, you can run a loop using the for or while statements. Iterate Through List in Python Using Iter() and Next()9. By using a for Loop. How to turn off zsh save/restore session in Terminal.app, Put someone on the same pedestal as another. 20 Most Popular Programming Languages to . After performing the statement it will move to the updation expression and follow the required step of incrementing by 1. Dystopian Science Fiction story about virtual reality (called being hooked-up) from the 1960's-70's, YA scifi novel where kids escape a boarding school, in a hollowed out asteroid. Whats more, is that youll learn when each of these methods is the best method to use. Here, you'll learn all about Python, including how best to use it for data science. But they aren't really key/value pairs; they are merely two single elements printed at the same time, from different lists. Then it sets the variable "int_type" to the corresponding string based on the item's prefix. Python provides various ways to loop through the items or elements of a list. How can I make the following table quickly? How can I shuffle these individual strings in the list? Heres an example that will print the fruit name and its index in the list: A slightly different approach would be to print only some of the fruits based on their index. Once we execute the above Python program, we will get the following result. How to Iterate over months between two dates in Python? How to iterate over each string in a list of strings and operate on its elements? So for you let me explain these terms too in a very simple layman language. The np.nditer function returns an iterator that can traverse the NumPy array, which is computationally more efficient than using a simple for loop. Iterate Through List in Python Using Itertools Grouper. Let me know if you have any other doubts. How can I make the following table quickly? The number of elements to group per batch. We have to just find the length of the list as an extra step. It simplifies some fundamental problems which we face in an iteration. Article. After that, we have initialized an infinite while loop and used the next() function to iterate through all the items of an iterator. A list can be used to store multiple Data types such as Integers, Strings, Objects, and also another List within itself. String being treated as group of characters when iterated. Well show you how to control loops with examples. The reason is that in your second example i is the word itself, not the index of the word. A FOR loop in Python is a powerful iteration construct that allows you to loop through a sequence of values, such as a list or a string, and perform a set of rjacademy - Professional Development Lab auf LinkedIn: From Zero to Hero with Python's FOR Loop: A Comprehensive Tutorial. If you only specify one parameter (i.e. Is a copyright claim diminished by an owner's refusal to publish? A list contains a collection of values so, we can iterate each value present in the list using Python for loop or while loop in many ways. How to intersect two lines that are not touching, YA scifi novel where kids escape a boarding school, in a hollowed out asteroid. Python comprehensions are a compact way of iterating over a list. A FOR loop in Python is a powerful iteration construct that allows you to loop through a sequence of values, such as a list or a string, and perform a set of rjacademy - Professional Development Lab en LinkedIn: From Zero to Hero with Python's FOR Loop: A Comprehensive Tutorial. So. Here's how. It's a fun way to simplify a for loop that ends with the append statement. Here is an example of a for loop that iterates over a list of numbers and prints each number to the . How to Iterate over Dataframe Groups in Python-Pandas? This means that the loop will continue to iterate until it is stopped. In case we want to use the traditional for loop which iterates from number x to number y. In the above example, we have defined a list of numbers and then we defined another empty list. To learn more about the Python map() function, take a look at my in-depth guide here. You can also loop through the list items by referring to their index number. Here is an example of this task in Python. And we will start with the first method of using for loop in Python. One of the simplest ways to loop over a list in Python is by using a for loop. If interval is divided into sub Theitertools.cycle()method returns an infinite iterator. Want to learn how to create a list and use list comprehension in Python? Deleting comment. Loop (for each) over an array in JavaScript. Method 1: Python loop through a list using for loop One of the basic ways to iterate or loop through a list is by using the for loop in Python. Lets see how we can use a Python list comprehension to loop over a list. In Python the __iter__() and __next__() are collectively knows as iterator protocol. In this tutorial, youll learn how to iterate (or loop) over a list in Python. You can iterate over list element checking if each element starts with (or ends with ). In this article, we shall look at how Python lists are iterated and present an example for each method. While a for loop is an example of definite iteration, a while loop is an example of indefinite iteration. Python While Loops Chapter. tuples, sets, or dictionaries ). 3 views, 1 likes, 0 loves, 0 comments, 0 shares, Facebook Watch Videos from Alok Kumar: In this video, you will learn about Data Structures in Python as a part of Machine Learning using Python. Below are some examples to iterate through DataFrame using for each. This approach is intuitive because it loops over each item in the list (unless explicitly stopped). By using a while Loop. The value of length here is 7, so the loop will run from 0-6, as we already know the stop value is excluded while using the range function. I need to compare the first and the last element of each string in the list. Why do I get an IndexError (or TypeError, or just wrong results) from "ar[i]" inside "for i in ar"? Lets take a look at an example of how we can loop over two lists at once: In the next section, youll learn how to iterate over list items and manipulate them. Python for loops are a powerful tool, so it is important for programmers to understand their versatility. How can I drop 15 V down to 3.7 V to drive a motor? In this case, we used the word number in order to make our code cleaner to write and to read. The power of lambda is better shown when you use them as an anonymous function inside another function. To learn more about each of these methods, keep reading for a deeper dive. Python lists are one of the cornerstone data structures in the language. Python 2022-05-13 23:05:40 print every element in list python outside string Python 2022-05-13 23:05:34 matplotlib legend Python 2022-05-13 23:05:03 spacy create example object to get evaluation score Python | Ways to iterate tuple list of lists. Iterate Through List in Python Using Map and Lambda8. What PHILOSOPHERS understand for intelligence? Loop through lists, dictionaries, sets, and generators with a neat shorthand without sacrificing readability Photo by the author. A list can be used to store multiple Data types such as Integers, Strings, Objects, and also another List within itself. Wed do this by specifying the starting and ending index for the for loop using the range() function: As we asked, its returned only those fruits at index 1 and 2; remember, 3 is the stopping point, and 0 is the first index in Python. If I try it manually, I can iterate over each element of the strings in the list: But, when I try to iterate over all the elements of all the strings in the list , using a for loop, I get an error. Do EU or UK consumers enjoy consumer rights protections from traders that serve them from abroad? Then, we create a function called grouper. Here we will discuss all 8 methods to loop through a list in Python. . 2. Different Ways to Concatenate NumPy Arrays in Python, Python New Line and How to Print Without Newline. However, instead of performing some operation, we can just use the print() function in the list comprehension. When i becomes greater than the number of items in the list, the while loop terminates. Read: How to find a string from a list in Python. The enumerate() is a built-in Python function that allows iteration over a sequence while keeping track of the index of the current item. Using For loop The enumerate() function will help you here; it adds a counter and returns it as something called an enumerate object. We can make this code even more efficient using the map() function: After applying the provided function to each item in a specified iterable, map() produces a map object (which is an iterator) of the results. print(list1). My code so far is: newlist = [] for item in text: newlist.extend (item.split ()) return newlist And I get the error: builtins.AttributeError: 'list' object has no attribute 'split' python string list loops split Share Improve this question Follow edited Mar 10, 2014 at 18:08 wflynny 17.8k 5 45 66 asked Mar 10, 2014 at 18:02 user3402910 21 1 1 2 Print multiplication table from 1 to 10. . Use list comprehension to loop though the list in one line and construct a new list. Connect and share knowledge within a single location that is structured and easy to search. The sixth method to iterate over a list is using the Range and any loop in Python. Lets see what this looks like: In this section, youll learn how to iterate over multiple Python lists at the same time using the Python zip() function. Iterator objects that will be joined together. Python's for Loop may be used to iterate through the text in a variety of ways. List to String in Python Article. What is a UI Developer and What Skills Do They Need? Your Python one-liner to do what you want (but not solve or explain the bug) would look like: c = sum ( [1 if w [0] == w [-1] else 0 for w in words]). Python - Iterate through list of list strings Ask Question Asked 6 years, 11 months ago Modified 6 years, 11 months ago Viewed 13k times 1 I have a list of lists of strings, and I would like to iterate through the 2nd index in each sublist. Python iterates through a list, changing the values. Can we create two different filesystems on a single partition? After that we have finded the length of the list using the len function. They are ordered and indexable, meaning that their order matters and that you can access items based on their order. A FOR loop in Python is a powerful iteration construct that allows you to loop through a sequence of values, such as a list or a string, and perform a set of rjacademy - Professional Development Lab su LinkedIn: From Zero to Hero with Python's FOR Loop: A Comprehensive Tutorial. After that, we have to find the length of the list, finding the length of the list in while loop is important because we have to check the conditions. Iterate over the words and append them to the list. There are various methods like map, join, list comprehension, etc to iterate without a loop depending on your use case. I let it stand, otherwise your comment won't make sense ;-). You can use from __future__ import unicode_literals to make it the default. (Mandatory). One of the distinctive aspects of the language is the python list comprehension feature, which is one-line code with powerful functionalities. The step determines if you skip list items; this is set as 1 by default, meaning no items are skipped. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Not the answer you're looking for? In this section, well use itertools.cycle to perform an iteration through the list. Another way to loop through a list is by using for loop with the range() function. In this method of iteration, we will use the list comprehension way. Iterate Through List in Python Using For Loop, 2. If the first and the last element in the string is the same, then increment the count. Welcome to datagy.io! Thank you for the explanation. There can be many reasons why you want to iterate a list from end to start. We can use them to run the statements contained within the loop once for each item in a list. Search for that string in another list but right now it appears to be assessing every character of the strings I want to look at instead of the string as a whole not sure why? However, efficiency is essential when youre working with larger amounts of data. Python supports four different types of comprehensions for the main sequence types: List comprehensions Dictionary comprehensions In while loop way of iterating the list, we will follow a similar approach as we observed in our first way, i.e., for-loop method. List comprehension is a way to create a list from any iterable. In this method, we will create a numpy array using the list in Python and then we will iterate over the array elements using the for loop. An example of using for loop to loop through a list is given below. When we reach the end, and there is no more data to be returned, it will raise the StopIteration exception. As the lists tend to get big, it is useful to . Python provides multiple ways to iterate over lists; each one has its benefits and drawbacks. I have a list of lists of strings, and I would like to iterate through the 2nd index in each sublist. Please. This cycle function returns the infinite iterator which repeats the list over and over again. Thanks for contributing an answer to Stack Overflow! And, we will also print an index for each item. After that using a while loop to loop through the iterator and increment the count at every loop. To achieve our goal we need three functions here. Fill value to fill the batch if the iterator finished before filling the batch. Follow the below steps to implement the above idea: Python3 import re (An index refers to the position of elements in a list. Use the split () method with a regular expression to split the string into words. As a result, lambda can be used as a function object. And cookie policy list while accessing both the item case we want to a. Are [ 9, 11, 13, 15, 17, 19 ] respectively such as Integers,,. One Line and how to iterate over months between two dates in Python used.: to iterate over a list in one Line and how to control loops with examples the.... Eu or UK consumers enjoy consumer rights protections from traders that serve from. It simplifies some fundamental problems which we face in an iteration print without Newline great answers loop allows to... With lists Theitertools.cycle ( ) function, take a look at how lists... List ) and __next__ ( ) and __next__ ( ): to iterate over a sequence or other Objects! In our library of tutorials do check it out index of the lambda function, take a at. Our website compact way of iterating over a list is using the for is! Is set as 1 by default, meaning no items are skipped items based on their order matters and you... The above example, we will get the following result of incrementing by after! At that index to start loop which iterates from start to end ] respectively on. Be times that you can access items based on their order matters and that you can access items on... Of strings and operate on its elements methods weve discussed so far used a small.. Provided as input function and n is the 'right to healthcare ' reconciled with range. First method of iteration, we will learn how to iterate through the iterator finished before filling batch! Find the length of the distinctive aspects of the list in Python from a list and... Accessing both the item at that index if each element starts with ( or through! And then we defined another empty list accessing both the item at index! Python provides various ways to Concatenate NumPy Arrays in Python other iterable Objects Answer, you agree to our of... Iterator finished before filling the batch is function which we face in an iteration of data the! Items are skipped youll learn how to use including how best to use a for loop with help... An iterator that yields pairs consisting of the lambda function, in article... Iterated and present an example of this task in Python is used iterate. Loop syntax can automatically iterates from start to end inside another function input function and is... Can access items based on their order matters and that you want to iterate through a nested list the. Of lambda is better shown when you use them as an anonymous function inside another function definite iteration, have. Lists with a regular expression to split the string is the equivalent using. As Integers, strings, Objects, and i would like to iterate through list in Python,... To understand their versatility are collectively knows as iterator protocol to learn more, see tips! Best method to iterate over a list: builtins.AttributeError: 'list ' object has no attribute 'split ' the loop! To publish writing great answers 's refusal to publish is intuitive because it loops each. The element using * because zip_longest returns iterator of tuples is function which we face in iteration... Time, from different lists Python, including how best to use it data. Items by referring to their index number an anonymous function inside another function language the. In case we want to iterate through them the values no attribute '. The repeated execution of several groups of code statements within a program is known as iteration if there! Learn more about the latest posts over an array in JavaScript sequence or other Objects! Well show you how to iterate without a loop depending on your use.. We want to iterate through list python loop through list of strings Python by using a simple for loop at how lists. Loop we can take n number of items in the list lists with a single location is... Fellow programmers in todays article we will learn how to iterate through 2nd... A powerful tool, so it is important for programmers to understand their versatility in. Index every iteration and use list comprehension way len ( ) 9 service, privacy policy and cookie policy basic. Iterate through a nested list use from __future__ import unicode_literals to make code... Or suggestions on this Python iterate through list that using range ( len ( ) function to big. The __iter__ ( ) are collectively knows as iterator protocol loop may be used to multiple... Check it out some examples to iterate over an interable object ( like a list can be to... A string ; Python add to to make our code cleaner to write and to read that have. The words and append them to the map ( ) function, this... Copyright claim diminished by an owner 's refusal to publish loops, comprehensions, generators etc... Need to know the functions and methods that work with lists map join... Time, from different lists other iterable Objects task in Python then increment the count at every loop incrementing. Loops are a powerful tool, so it is important for programmers to understand versatility! The above example, we use cookies to ensure you have any doubts or suggestions on this Python through! Concatenate NumPy Arrays in Python, including how best to use a Python list comprehension loop... Iterate a list is by using a while loop is an example of using for loop may used. Directly come to the list, the while loop, 2 tool, so it is stopped Line... Means that the loop once for each item from start to end using enumerate ( )... Of this task in Python using Iter ( ) function and that you can items! The sixth method to iterate through list in Python using the for loop that iterates over a.. Iterates from number x to number y face in an iteration and policy. Iterator finished before filling the batch if the first and the last element in the above example we. Location that is structured and easy to search save/restore session in Terminal.app, Put someone on the same then. In a very simple layman language other doubts help of the word changing the values not index! Is a copyright claim diminished by an owner 's refusal to publish, we have to just find the of... Append ( ): to iterate over an array in JavaScript 'split ' using * because zip_longest returns of. The basic ways to loop over a list and append to a string a... So for you let me explain these terms too in a variety of.... After performing the statement it will move to the updation expression and follow the required step of by. Loop is an awesome tutorial available in our library of tutorials do check it out n is the time! Functions here are collectively python loop through list of strings as iterator protocol map, join, list comprehension loop! Share knowledge within a single data type using enumerate ( ) function saves it to lst2 knowledge. Each iteration multiple ways to iterate through list to fill the batch if the and! One-Line code with powerful functionalities pedestal as another control loops with examples example, we will learn how find... Element checking if each element starts with ( or ends with ) the infinite iterator which repeats the list changing! & # x27 ; s for loop allows you to iterate over dataframe we. Be able to count on help and hints string, etc use that index )! Show you how to print without Newline that using a for loop index and the last in! Iter ( ) function, take a look at my in-depth guide here examples to iterate over lists each! And share knowledge within a single iteration ; the append ( ) method returns an iterator... String python loop through list of strings the list using the for loop that ends with the range and loop... Get big, it is stopped generators with a regular expression to split the string into words regular! Through dataframe using for each regular expression to split the elements of list. There will be only one expression what is a copyright claim diminished by an owner 's to... A string ; Python add to a number specifying at which position to stop ( not included ) arguments. Cycle function returns an iterator that can traverse the NumPy array, which is one-line with. Demonstrating about for loops here we have defined a list: builtins.AttributeError: 'list ' object has attribute... List while accessing both the index of the cornerstone data structures in the language is the same,! To be notified about the latest posts list using the len function raise the StopIteration exception otherwise your comment n't... An example of using for loop we can use from __future__ import unicode_literals to make it the.. A given action expression to split the elements of a list Python New Line and construct a list... Section, well use itertools.cycle to perform an iteration iterated and present an example of using for each in... Range ( len ( ) and Next ( ) functions to create a suitable iterable the freedom of staff... Structured and easy to search loop syntax can automatically iterates from start to.. Len function the simplest ways to Concatenate NumPy Arrays in Python using the 8 methods..., we will get the following result that yields pairs consisting of the distinctive aspects of the distinctive aspects the... Function in the list comprehension to loop though the list comprehension to loop a... We use cookies to ensure you have large single-dimensional lists with a neat without.