Array Methods

Array Methods

The array methods are the built-in methods in Python. These methods are used to perform different operations on the array. In this tutorial, we will learn how to use the array methods in Python with the help of examples.

Table of Methods

There are various methods available in Python to perform different operations on the array. The following table lists some of the important methods available in Python.

S.No.	Method	Description	Example
1	append()	Adds an element at the end of the array	arr.append(5)
2	insert()	Adds an element at the specified position	arr.insert(2, 5)
3	remove()	Removes the first occurrence of the element with the specified value	arr.remove(5)
4	pop()	Removes the element at the specified position	arr.pop(2)
5	clear()	Removes all the elements from the array	arr.clear()
6	index()	Returns the index of the first element with the specified value	arr.index(5)
7	count()	Returns the number of elements with the specified value	arr.count(5)
8	sort()	Sorts the array	arr.sort()
9	reverse()	Reverses the order of the array	arr.reverse()
10	copy()	Returns a copy of the array	arr.copy()
11	extend()	Adds the elements of an array to the end of the current array	arr.extend(arr2)
12	fromlist()	Appends the contents of the list to the array	arr.fromlist(list)
13	tolist()	Converts the array to an ordinary list with the same items	arr.tolist()
14	tofile()	Writes all the array elements to a file	arr.tofile(f)
15	typecode()	Returns the type code of the array	arr.typecode
16	itemsize()	Returns the size of each element of the array in bytes	arr.itemsize
17	buffer_info()	Returns a tuple containing the address in which array is stored and the number of elements in it	arr.buffer_info()
18	byteswap()	Reverses the order of the bytes in the array	arr.byteswap()
19	frombytes()	Appends bytes from the string to the array	arr.frombytes(s)
20	fromfile()	Reads the array from the file, according to the dtype	arr.fromfile(f, n)
21	fromstring()	Appends items from the string into the array	arr.fromstring(s)
22	fromunicode()	Appends items from the unicode string into the array	arr.fromunicode(s)
23	tobytes()	Converts the array to an array of machine values and returns the bytes representation	arr.tobytes()

append() Method

The append() method adds an element at the end of the array. The syntax of the append() method is:

append.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
my_array.append(6)
 
print(my_array)

Output:

command

C:\Users\username>python append.py
array('i', [1, 2, 3, 4, 5, 6])

In the above example, we create an array of five elements and append a new element at the end of the array. The new element is added at the end of the array.

insert() Method

The insert() method adds an element at the specified position. The syntax of the insert() method is:

insert.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
my_array.insert(2, 6)
 
print(my_array)

Output:

command

C:\Users\username>python insert.py
array('i', [1, 2, 6, 3, 4, 5])

In the above example, we create an array of five elements and insert a new element at the second position. The new element is added at the second position and the remaining elements are shifted to the right.

remove() Method

The remove() method removes the first occurrence of the element with the specified value. The syntax of the remove() method is:

remove.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
my_array.remove(4)
 
print(my_array)

Output:

command

C:\Users\username>python remove.py
array('i', [1, 2, 3, 5])

In the above example, we create an array of five elements and remove the element with the value 4. The first occurrence of the element with the value 4 is removed from the array.

pop() Method

The pop() method removes the element at the specified position. The syntax of the pop() method is:

pop.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
my_array.pop(2)
 
print(my_array)

Output:

command

C:\Users\username>python pop.py
array('i', [1, 2, 4, 5])

In the above example, we create an array of five elements and remove the element at the second position. The element at the second position is removed from the array.

clear() Method

The clear() method removes all the elements from the array. The syntax of the clear() method is:

clear.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
my_array.clear()
 
print(my_array)

Output:

command

C:\Users\username>python clear.py
array('i')

In the above example, we create an array of five elements and remove all the elements from the array. The array becomes empty after removing all the elements.

index() Method

The index() method returns the index of the first occurrence of the element with the specified value. The syntax of the index() method is:

index.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 2, 4, 5])
print(my_array.index(2))

Output:

command

C:\Users\username>python index.py
1

In the above example, we create an array of six elements and find the index of the first occurrence of the element with the value 2. The index of the first occurrence of the element with the value 2 is 1.

count() Method

The count() method returns the number of elements with the specified value. The syntax of the count() method is:

count.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 2, 4, 5])
print(my_array.count(2))

Output:

command

C:\Users\username>python count.py
2

In the above example, we create an array of six elements and count the number of elements with the value 2. The number of elements with the value 2 is 2.

sort() Method

The sort() method sorts the array. The syntax of the sort() method is:

sort.py

import array as arr
 
my_array = arr.array('i', [3, 2, 5, 4, 1])
my_array.sort()
 
print(my_array)

Output:

command

C:\Users\username>python sort.py
array('i', [1, 2, 3, 4, 5])

In the above example, we create an array of five elements and sort the array. The elements of the array are sorted in ascending order.

reverse() Method

The reverse() method reverses the order of the array. The syntax of the reverse() method is:

reverse.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
my_array.reverse()
 
print(my_array)

Output:

command

C:\Users\username>python reverse.py
array('i', [5, 4, 3, 2, 1])

In the above example, we create an array of five elements and reverse the order of the array. The elements of the array are reversed.

copy() Method

The copy() method returns a copy of the array. The syntax of the copy() method is:

copy.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
new_array = my_array.copy()
 
print(new_array)

Output:

command

C:\Users\username>python copy.py
array('i', [1, 2, 3, 4, 5])

In the above example, we create an array of five elements and copy the array to a new array. The new array is a copy of the original array.

extend() Method

The extend() method adds the elements of an iterable to the end of the array. The syntax of the extend() method is:

extend.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
my_array.extend([6, 7, 8])
 
print(my_array)

Output:

command

C:\Users\username>python extend.py
array('i', [1, 2, 3, 4, 5, 6, 7, 8])

In the above example, we create an array of five elements and extend the array with three new elements. The three new elements are added at the end of the array.

fromlist() Method

The fromlist() method appends the contents of the list to the array. The syntax of the fromlist() method is:

fromlist.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
my_list = [6, 7, 8]
 
my_array.fromlist(my_list)
 
print(my_array)

Output:

command

C:\Users\username>python fromlist.py
array('i', [1, 2, 3, 4, 5, 6, 7, 8])

In the above example, we create an array of five elements and append the contents of the list to the array. The contents of the list are added at the end of the array.

tolist() Method

The tolist() method converts the array to an ordinary list with the same items. The syntax of the tolist() method is:

tolist.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
print(my_array.tolist())

Output:

command

C:\Users\username>python tolist.py
[1, 2, 3, 4, 5]

In the above example, we create an array of five elements and convert the array to a list. The array is converted to a list with the same items.

tofile() Method

The tofile() method writes all the array elements to a file. The syntax of the tofile() method is:

tofile.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
f = open('my_array.txt', 'w')
my_array.tofile(f)
f.close()

Output:

command

C:\Users\username>python tofile.py

my_array.txt

1 2 3 4 5

In the above example, we create an array of five elements and write the array elements to a file. The array elements are written to the file in the same order.

typecode() Method

The typecode() method returns the type code of the array. The syntax of the typecode() method is:

typecode.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
print(my_array.typecode)

Output:

command

C:\Users\username>python typecode.py
i

In the above example, we create an array of five elements and print the type code of the array. The type code of the array is i.

itemsize() Method

The itemsize() method returns the size of each element of the array in bytes. The syntax of the itemsize() method is:

itemsize.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
print(my_array.itemsize)

Output:

command

C:\Users\username>python itemsize.py
4

In the above example, we create an array of five elements and print the size of each element of the array in bytes. The size of each element of the array is 4 bytes.

buffer_info() Method

The buffer_info() method returns a tuple containing the address in which array is stored and the number of elements in it. The syntax of the buffer_info() method is:

buffer_info.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
print(my_array.buffer_info())

Output:

command

C:\Users\username>python buffer_info.py
(140714816, 5)

In the above example, we create an array of five elements and print the address in which the array is stored and the number of elements in it. The address in which the array is stored is 140714816 and the number of elements in the array is 5.

byteswap() Method

The byteswap() method reverses the order of the bytes in the array. The syntax of the byteswap() method is:

byteswap.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
my_array.byteswap()
 
print(my_array)

Output:

command

C:\Users\username>python byteswap.py
array('i', [16777216, 33554432, 50331648, 67108864, 83886080])

In the above example, we create an array of five elements and reverse the order of the bytes in the array. The order of the bytes in the array is reversed.

frombytes() Method

The frombytes() method appends bytes from the string to the array. The syntax of the frombytes() method is:

frombytes.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
s = my_array.tostring()
my_array.frombytes(s)
print(my_array)

Output:

command

C:\Users\username>python frombytes.py
array('i', [1, 2, 3, 4, 5, 1, 2, 3, 4, 5])

In the above example, we create an array of five elements and append bytes from the string to the array. The bytes from the string are appended to the array.

fromfile() Method

The fromfile() method reads the array from the file, according to the dtype. The syntax of the fromfile() method is:

fromfile.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
f = open('my_array.txt', 'r')
my_array.fromfile(f, 5)
f.close()
 
print(my_array)

Output:

command

C:\Users\username>python fromfile.py
array('i', [1, 2, 3, 4, 5])

my_array.txt

1 2 3 4 5

In the above example, we create an array of five elements and read the array from the file. The array is read from the file and stored in the array.

fromstring() Method

The fromstring() method appends items from the string into the array. The syntax of the fromstring() method is:

fromstring.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
s = my_array.tostring()
my_array.fromstring(s)
print(my_array)

Output:

command

C:\Users\username>python fromstring.py
array('i', [1, 2, 3, 4, 5, 1, 2, 3, 4, 5])

In the above example, we create an array of five elements and append items from the string into the array. The items from the string are appended to the array.

fromunicode() Method

The fromunicode() method appends items from the unicode string into the array. The syntax of the fromunicode() method is:

fromunicode.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
s = my_array.tostring()
my_array.fromunicode(s)
print(my_array)

Output:

command

C:\Users\username>python fromunicode.py
array('i', [1, 2, 3, 4, 5, 1, 2, 3, 4, 5])

In the above example, we create an array of five elements and append items from the unicode string into the array. The items from the unicode string are appended to the array.

tobytes() Method

The tobytes() method converts the array to an array of machine values and returns the bytes representation. The syntax of the tobytes() method is:

tobytes.py

import array as arr
 
my_array = arr.array('i', [1, 2, 3, 4, 5])
 
print(my_array.tobytes())

Output:

command

C:\Users\username>python tobytes.py
b'\x01\x00\x00\x00\x02\x00\x00\x00\x03\x00\x00\x00\x04\x00\x00\x00\x05\x00\x00\x00'

In the above example, we create an array of five elements and convert the array to an array of machine values and returns the bytes representation. The array is converted to an array of machine values and returns the bytes representation.

Conclusion

In this tutorial, we have learned how to use the array methods in Python with the help of examples. The array methods are the built-in methods in Python. These methods are used to perform different operations on the array. For more information, visit the official documentation of the array methods. For more tutorials, visit our Python Central Hub.

---

diagram the methods an array adds, and what they are for mermaid

  flowchart LR
  subgraph "list-like"
    A["append, extend, insert"]
    B["remove, pop, clear"]
    C["index, count, reverse"]
  end
  subgraph "about the raw block"
    D["typecode, itemsize"]
    E["tobytes / frombytes"]
    F["tofile / fromfile"]
    G["tolist / fromlist"]
    H["buffer_info, byteswap"]
  end
  E --> I["the bytes carry NO type information"]
  I --> J["reading them back needs the SAME typecode"]
  H --> K["byteswap matters when the file came from another machine"]

Beyond the list-like operations, an array carries a second set concerned with its raw representation -- converting to and from bytes, reading and writing files directly, and reporting the typecode and item size. Those exist because the storage is a plain block of fixed-width values, which a list is not.

sketch tobytes forgets the type, and frombytes will not remind you p5.js Pause Restart

Three integers are written out as twelve bytes. Reading those bytes back with the same typecode restores them exactly. Reading the same bytes as a two-byte type produces six numbers instead of three -- no error, no warning, because the bytes on their own say nothing about how wide each value was.

Check yourself

pch.quizTag pch.quizDefaultTitle

1. `array('i', [1,2,3]).tobytes()` gives 12 bytes. Reading them back with `array('h').frombytes(...)` gives what?

   A `[1, 2, 3]` B `[1, 0, 2, 0, 3, 0]` C A `ValueError` D An empty array
   pch.quizShowAnswer

   B — `[1, 0, 2, 0, 3, 0]` — Verified. The bytes record nothing about the width they were written with, so a 2-byte typecode reads six values out of the same twelve bytes — silently.

2. What information does `tobytes()` NOT preserve?

   A The values B The typecode, the element count and the byte order C The length in bytes D Nothing is lost
   pch.quizShowAnswer

   B — The typecode, the element count and the byte order — It is a raw dump. Store the typecode alongside it, or use a format that carries its own metadata — `pickle`, `.npy`, or a header of your own.

3. What is `byteswap()` for?

   A Reversing the array B Converting between big-endian and little-endian data C Swapping two elements D Converting the typecode
   pch.quizShowAnswer

   B — Converting between big-endian and little-endian data — It matters when a binary file was written on a machine with the opposite byte order. Nothing in the raw bytes tells you which — that is metadata you have to carry yourself.

4. Which pair reports how the array is stored?

   A `tolist` and `fromlist` B `typecode` and `itemsize` C `index` and `count` D `tofile` and `fromfile`
   pch.quizShowAnswer

   B — `typecode` and `itemsize` — `typecode` is the declared letter, `itemsize` the bytes per element — measured as 1 for `'b'`, 4 for `'i'`, and 8 for `'d'`.

Try it: Array Methods Exercises

Exercise 1 – index() and count()

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Exercise 2 – reverse()

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Exercise 3 – Convert to List

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