Enumerate python

The enumerate() function is one of the built-in functions in Python. It provides a handy way to access each item in an iterable, along with a count value that specifies the order in which the item was accessed. In this article you will learn all that you need to get started using enumerate() in your code. Namely, we will explore: • When you'd want to use enumerate • enumerate() syntax and input arguments • different ways to invoke enumerate() using built-in iterables • how to invoke enumerate() using a custom iterable • how to use enumerate() in a for loop Let's get started. When Should You Use Enumerate? Let's take an example. Suppose we have a list of student names: names = ["Wednesday", "Enid", "Rowan", "Bianca"] We want to create a list of tuples, where each tuple item contains a student ID number and student name like this: [(0, 'Wednesday'), (1, 'Enid'), (2, 'Rowan'), (3, 'Bianca')] The student ID is the index of the student name in the names list. So in the tuple (3, 'Bianca') student Bianca has an ID of 3 since Bianca is at index 3 in the names list. Similarly in (0, 'Wednesday'), student Wednesday has an ID of 0 since she is at index 0 in the names list. Whenever we come across situations when we want to use a list item as well the index of that list item together, we use enumerate(). enumerate() will automatically keep track of the order in which items are accessed, which gives us the index value without the need to maintain a separate index variable. Here's how ...

Enum HOWTO An Enum is a set of symbolic names bound to unique values. They are similar to global variables, but they offer a more useful repr(), grouping, type-safety, and a few other features. They are most useful when you have a variable that can take one of a limited selection of values. For example, the days of the week: Note Case of Enum Members Because Enums are used to represent constants we recommend using UPPER_CASE names for members, and will be using that style in our examples. Depending on the nature of the enum a member’s value may or may not be important, but either way that value can be used to get the corresponding member: >>> Weekday . WEDNESDAY . value 3 Unlike many languages that treat enumerations solely as name/value pairs, Python Enums can have behavior added. For example, datetime.date has two methods for returning the weekday: weekday() and isoweekday(). The difference is that one of them counts from 0-6 and the other from 1-7. Rather than keep track of that ourselves we can add a method to the Weekday enum to extract the day from the date instance and return the matching enum member: >>> from datetime import date >>> Weekday . from_date ( date . today ()) Of course, if you’re reading this on some other day, you’ll see that day instead. This Weekday enum is great if our variable only needs one day, but what if we need several? Maybe we’re writing a function to plot chores during a week, and don’t want to use a list – we could use a different type o...

Enumerate Explained (With Examples) The enumerate() function is a built-in function that returns an enumerate object. This lets you get the index of an element while iterating over a list. In other programming languages (C), you often use a for loop to get the index, where you use the length of the array and then get the index using that. That is not Pythonic, instead you should use enumerate(). In Python you can iterate over the list while getting the index and value immediately. Related course: The basic syntax is is enumerate(sequence, start=0) The output object includes a counter like so: (0, thing[0]), (1, thing[1]), (2, thing[2]), As input it takes a sequence like a list, tuple or iterator. The start parameter is optional. If the start parameter is set to one, counting will start from one instead of zero Create a sequence and feed it to the enumerate function. This can be any type of sequence, in this example we use a list. Then we output the object. Try the program below: 1 2 3 4 5 6 # create a sequence browsers = [ 'Chrome', 'Firefox', 'Opera', 'Vivaldi'] # create an enumeratable and convert to list x = list(enumerate(browsers)) print(x) You should see this output: The returned object can be treated like an iterator: the next method call will work: 1 2 3 4 5 6 7 browsers = [ 'Chrome', 'Firefox', 'Opera', 'Vivaldi'] eObj = enumerate(browsers) x = next(eObj) print(x) x = next(eObj) print(x) Let’s see how you can enumerate a Python list. You can open the Python shell ...

Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Looping With Python enumerate() In Python, a for loop is usually written as a loop over an iterable object. This means you don’t need a counting variable to access items in the iterable. Sometimes, though, you do want to have a variable that changes on each loop iteration. Rather than creating and incrementing a variable yourself, you can use Python’s enumerate() to get a counter and the value from the iterable at the same time! In this tutorial, you’ll see how to: • Use enumerate() to get a counter in a loop • Apply enumerate() to display item counts • Use enumerate() with conditional statements • Implement your own equivalent function to enumerate() • Unpack values returned by enumerate() Let’s get started! >>> >>> values = [ "a" , "b" , "c" ] >>> for value in values : ... print ( value ) ... a b c In this example, values is a "a", "b", and "c". In Python, lists are one type of iterable object. In the for loop, the loop variable is value. On each iteration of the loop, value is set to the next item from values. Next, you value onto the screen. The advantage of collection-based iteration is that it helps avoid the Now imagine that, in addition to the value itself, you want to print the index of the item in the list to the screen on every iteration. One way to approach this task is to create a variable to store the in...

Often, when dealing with iterators, we also get need to keep a count of iterations. Python eases the programmers’ task by providing a built-in function enumerate() for this task. Enumerate() method adds a counter to an iterable and returns it in a form of enumerating object. This enumerated object can then be used directly for loops or converted into a list of tuples using the list() function. Syntax: enumerate(iterable, start=0) Parameters: • Iterable: any object that supports iteration • Start: the index value from which the counter is to be started, by default it is 0 Example Output: (0, 'eat') (1, 'sleep') (2, 'repeat') 100 eat 101 sleep 102 repeat 0 eat 1 sleep 2 repeat This article is contributed by Harshit Agrawal. If you like GeeksforGeeks and would like to contribute, you can also write an article using Please write comments if you find anything incorrect, or have more information about the topic discussed above.

New in version 3.4. Source code: Important This page contains the API reference information. For tutorial information and discussion of more advanced topics, see • Basic Tutorial • Advanced Tutorial • Enum Cookbook An enumeration: • is a set of symbolic names (members) bound to unique values • can be iterated over to return its canonical (i.e. non-alias) members in definition order • uses call syntax to return members by value • uses index syntax to return members by name Enumerations are created either by using class syntax, or by using function-call syntax: >>> from enum import Enum >>> # class syntax >>> class Color ( Enum ): ... RED = 1 ... GREEN = 2 ... BLUE = 3 >>> # functional syntax >>> Color = Enum ( 'Color' , [ 'RED' , 'GREEN' , 'BLUE' ]) Even though we can use class syntax to create Enums, Enums are not normal Python classes. See How are Enums different? for more details. Note Nomenclature • The class Color is an enumeration (or enum) • The attributes Color.RED, Color.GREEN, etc., are enumeration members (or members) and are functionally constants. • The enum members have names and values (the name of Color.RED is RED, the value of Color.BLUE is 3, etc.) Module Contents New in version 3.11: StrEnum, EnumCheck, ReprEnum, FlagBoundary, property, member, nonmember, global_enum, show_flag_values Data Types class enum. EnumType EnumType is the metaclass for enum enumerations. It is possible to subclass EnumType – see Subclassing EnumType for details. EnumType is resp...