Python Array Length
Python Array Length:
Let’s first learn what an array is before we can figure out how to determine its size in Python. Python arrays are data structures that store multiple values in one variable. Since it can store items of the same data type, it is a convenient way to store large amounts of data. Array is basically memory allocation process how this variable use the memory of computer.
What is Array ?
The array is a data structure that allows values to be arranged linearly, which means each value occupies contiguous memory. An array has the same type of data for all its elements.
By knowing the first memory location and adding the offset, it becomes easier to find the memory location of any element in the array.
In order to understand an array better, think of it as a flight of stairs where on each step there is a value (let’s say one of your friends). By knowing the number of the step each friend is on, you can locate them.
This makes it easier to calculate the position of each element by simply adding an offset to a base value, i.e., the memory location of the first element of the array (generally denoted by the array’s name). Base value is 0 and offset is the difference between the two indexes.
Why use Arrays in Python?
A Python and arrays combined could save you a lot of time. As mentioned previously, arrays reduce the size of your code while Python eliminates problematic syntax, unlike other languages. For example, if you had to store integers from 1–100, you would not be able to remember 100 variable names explicitly, so an array can be used to save them.
Python arrays are linear-ordered data structures that store the elements of the same data type at contiguous memory locations.
- Arrays are not-built into a data structure
- Array in Python is mutable.
- The index value in the Array goes from 0 to n-1 (where n is the Array’s length).
- Arrays are size efficient
- As they are very compact and take less memory space
Specifically, they are an ordered collection of elements with every value being of the same data type. That is the most important thing to remember about Python arrays — the fact that they can only hold a sequence of multiple items that are of the same type.
How to Define Arrays in Python ?
The general syntax for creating an array looks like this:
variable_name = array(typecode,[elements])
- variable_name would be the name of the array.
- The typecode specifies what kind of elements would be stored in the array. Whether it would be an array of integers, an array of floats or an array of any other Python data type. Remember that all elements should be of the same data type.
- Inside square brackets you mention the elements that would be stored in the array, with each element being separated by a comma. You can also create an empty array by just writing variable_name = array(typecode) alone, without any elements.
Below is a typecode table, with the different typecodes that can be used with the different data types when defining Python arrays:
What’s the Difference between Python Lists and Python Arrays?
Lists are one of the most common data structures in Python, and a core part of the language.
Lists and arrays behave similarly.
Just like arrays, lists are an ordered sequence of elements.
They are also mutable and not fixed in size, which means they can grow and shrink throughout the life of the program. Items can be added and removed, making them very flexible to work with.
However, lists and arrays are not the same thing.
Lists store items that are of various data types. This means that a list can contain integers, floating point numbers, strings, or any other Python data type, at the same time. That is not the case with arrays.
As mentioned in the section above, arrays store only items that are of the same single data type. There are arrays that contain only integers, or only floating point numbers, or only any other Python data type you want to use.
How to Access Individual Items in an Array in Python:
Each item in an array has a specific address. Individual items are accessed by referencing their index number.
Indexing in Python, and in all programming languages and computing in general, starts at 0. It is important to remember that counting starts at 0 and not at 1.
To access an element, you first write the name of the array followed by square brackets. Inside the square brackets you include the item’s index number.
The general syntax would look something like this:
Array_name[index_value_of_item]
Here is how you would access each individual element in an array:
import array as arr
numbers = arr.array(‘i’,[10,20,30])
print(numbers[0]) # gets the 1st element
print(numbers[1]) # gets the 2nd element
print(numbers[2]) # gets the 3rd element
#output
10
20
30
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How to Search Through an Array in Python ?
You can find out an element’s index number by using the index() method.
You pass the value of the element being searched as the argument to the method, and the element’s index number is returned.
import array as arr
numbers = arr.array(‘i’,[10,20,30])
#search for the index of the value 10
print(numbers.index(10))
#output
#0
Use of Array lengthen python :
The len() function in Python can be used to find the length of an array. The function returns the number of elements in the array. This article will explain how to find the length of Python arrays.
Syntax:
len(array)
arr = [1, 2, 3, 4, 5]
Length = 5
type(arr)
Python uses Lists instead of arrays. Both are similar and are used to work as an array. Let us see how we can find the length of a Python array
Python Array Length using len() Method
The Python len() function can be used to find the length of an array in Python. The len() function returns the length of the list or array.
import array as arr
numbers = arr.array(‘i’,[10,20,30])
print(len(numbers))
#output
# 3
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.
Example:
lst = [1,2,3,4,’Python’]
print(“List elements: “,lst)
print(“Length of the list:”,len(lst))
Output:
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))
Output:
Array elements: array(‘i’, [1, 2, 3, 4, 5])
Length of array: 5
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.
