Python get array size

Python: Length or size of list, tuple, array

How to get the length of a list or tuple or array in Python #

Let me clarify something at the beginning, by array , you probably mean list in Python. list is the equivalent of arrays in JavaScript or PHP. Arrays in Python is an altogether different thing.

Ok, having cleared that, getting the the size of a list or tuple (or array , if you will), is pretty straighforward. You just call the len() function on the object, and there you have it’s size. Examples of list and tuple size / lengths are given below.

>>> fighters = ['bruce', 'chuck', 'benny'] >>> len(fighters) 3

>>> movie = ('Terminator', 'James Cameron', 'Arnold Schwarzenegger') >>> len(movie) 3

So there it is, you just call the global function len() on the list or tuple and you get its size / length.

Did you expect to have something like list.len() or tuple.len() instead? Actually there is something like that, but it is called list.__len__() or tuple.__len__() . And what len() really does is, it takes the object and tries to call the objects’s __len__() method. So essentially, len() works only on objects that has a __len__() method. If you have a custom object that has the __len__() method, you can call len() even on that.

So you learnt: to get the size or length of a list or tuple in Python (you probably didn’t mean Python array ), you just call the len() function on the object.

Notes #

1. If you came from PHP / JavaScript, by array , probably you mean list in Python.
2. You can make your custom objects return values to the len() function.

Exercise #

1. Create a custom object which returns weird values for len() and shock your family and friends.
2. Why isn’t there list.len() or tuple.len() , instead there is list.__len__() or tuple.__len__() ?

References #

Related

• Python: Difference between urllib and urllib2 What is the difference between urllib and urllib2 modules of Python? You might be intrigued by the existence of two separate URL modules in Python — urllib and urllib2. Even more intriguing: they are. Jul 27, 2011
• JavaScript: Get object size How to get the size of an object in JavaScript Arrays in JavaScript have a length property that gives you the number of items in an array. Objects on the other hand, don’t have a length or size prope. Jan 24, 2012
• JavaScript: Array splice() with examples JavaScript array.splice() explained with examples .splice() is an instance method on all JavaScript arrays. Depending on the parameters you pass, it has a very multipurpose functionality. Here is wha. Feb 14, 2010

Источник

How to calculate the length of an array in Python?

An array is not a built-in data type in Python, but we can create arrays using third-party libraries. By length of an array, we mean the total number of elements or items in the given array. In order to calculate the length of an array, we can use various methods discussed below in this blog.

Table of contents

1. Length of array
2. Finding the length of an array using the len() function
3. Using Numpy to find the length of an array in Python
4. Closing thoughts

Length of array

In Python, an array is a collection of items stored at contiguous memory locations. It is a special variable, which can hold more than one value with the same data type at a time. We know array index starts from 0 instead of 1, therefore the length of an array is one more than the highest index value of the given array.

Finding the length of an array using the len() function

To find the length of an array in Python, we can use the len() function. It is a built-in Python method that takes an array as an argument and returns the number of elements in the array. The len() function returns the size of an array.

Syntax:

Input:

arr = [0, 1, 2, a, 4] print ("The given array is: ") print (arr) # Finding length of the given array size = len(arr) print ("The length of array is: ") print (size) 

Output:

The given array is: [0, 1, 2, a, 4] The length of array is: 5

Using Numpy to find the length of an array in Python

Another method to find the length of an array is Numpy «size». Numpy has a size attribute. The size is a built-in attribute that returns the size of the array.

Syntax:

Input:

import numpy as np arr = np.array([0, 1, 2, a, 4]) print ("The given array is: ") print (arr) # Finding length of the given array size = arr.size print ("The length of array is: ") print (size) 

Output:

The given array is: [0, 1, 2, a, 4] The length of array is: 5

Closing thoughts

Unlike other programming languages like JavaScript, PHP or C++, Python does not support «length()» or «size()» functions to find the length of an array. The len() function takes the array as a parameter and returns the size. One can read more about other Python concepts here.

Источник

How to Find the Array Length in Python

Python len() method is used to find the length of an array. As we all know, python does not support or provide us with the array data structure in a direct way. Instead, python serves with three different variations of using an array data structure.

In this tutorial, we will learn about the fundamentals of the different array variants that can use to create an array in python and then we will discuss the use of the len() method to obtain the length of an array in each variant.

Finding the length of an Array using the len() Method

We have three methods to create an array in Python, which we will use to demonstrate the use of the len() method.

To demonstrate the len() method, we’ll use all of these types of arrays, but before that let’s take a look at the syntax of len() method.

len() Method in Python

Python len() method enables us to find the total number of elements in an array. It returns the count of the elements in an array.

Here, the array can be any type of array for which we want to find the length.

Finding the Length of a Python List using len() Method

The Python len() method can be used to fetch and display the number of elements contained in the list.

In the below example, we have created a list of heterogeneous elements. Further, we have used len() method to display the length of the list.

lst = [1,2,3,4,'Python'] print("List elements: ",lst) print("Length of the list:",len(lst))

List elements: [1, 2, 3, 4, 'Python'] Length of the list: 5

Finding the Length of a Python Array using len() Method

Python Array module helps us create an array and manipulate the same using various functions of the module. The len() method can also be used to calculate the length of an array created using the Array module.

import array as A arr = A.array('i',[1,2,3,4,5]) print("Array elements: ",arr) print("Length of array: ",len(arr))

Array elements: array('i', [1, 2, 3, 4, 5]) Length of array: 5

Finding the Length of a Python NumPy Array using len() Method

As we all know, we can create an array using NumPy module and use it for any mathematical purpose. The len() method helps us find out the number of data values present in a NumPy array.

import numpy as np arr = np.arange(5) len_arr = len(arr) print("Array elements: ",arr) print("Length of NumPy array: ",len_arr)

Array elements: [0 1 2 3 4] Length of NumPy array: 5

Conclusion

In this tutorial, we learned to use the len() method to find the length of different arrays in Python. We have given you many examples so that you can learn them well. Hope you find this tutorial useful.

Источник

Length of Array in Python

We have learned that arrays are a collection of objects , and these collections can have any number of objects: zero, one, ten, and so on. The number of objects in the array is called its length. We need to know the length of an array to perform various operations like iterating over the array, checking whether an element belongs to the array and reading/updating elements in the array.

Introduction

Let us take an array as follows:

How many elements are in the array? The answer is 5. Hence the length of the array is also 5.

If we were to give indexes to each element in the array as follows:

Essentially, the length of an array is the highest index position + 1.

Array Length in Python using the len() method

Python has a len() method to find out the length of an array. The syntax is as follows:

Finding the Length of a Python NumPy Array

Numpy is a library compatible with Python for operating complex mathematical operations on multi-dimensional arrays . We use numpy for mathematical operations on arrays. Here is how we can find the length of an array in Python using numpy:

Conclusion

• Length of an array is the number of elements present in the array.
• In python, the length of an array is the highest index of an array + 1 .
• We can use Python’s len() function to find the length of an array.
• For a Numpy array also, we can use the len() function to find the array’s length in Python .

Источник