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      Array Methods

      Python Tutorial

      This Python tutorial has been written for the beginners to help them understand the basic to advanced concepts of Python Programming Language. After completing this tutorial, you will find yourself at a great level of expertise in Python, from where you can take yourself to the next levels to become a world class Software Engineer.

      Array Methods

      array.reverse() Method

      Like the sequence types, the array class also supports the reverse() method which rearranges the elements in reverse order.

      Syntax

      array.reverse()

      Parameters

      This method has no parameters

      Example

      import array as arr
      a = arr.array('i', [1, 2, 3, 4, 5])
      a.reverse()
      print (a)
      It will produce the following output
      array('i', [5, 4, 3, 2, 1])
      The array class also defines the following useful methods.

      array.count() Method

      The count() method returns the number of times a given element occurs in the array.

      Syntax

      array.count(v)

      Parameters

      • v − The value whose occurrences are to be counted

      Return value

      The count() method returns an integer corresponding the number of times v appears in the array.

      Example

      import array as arr
      a = arr.array('i', [1, 2, 3, 2, 5, 6, 2, 9])
      c = a.count(2)
      print ("Count of 2:", c)
      It will produce the following output
      Count of 2: 3

      array.index() method

      The index() method in array class finds the position of first occurrence of a given element in the array.

      Syntax

      array.index(v)

      Parameters

      • v − the value for which the index is to be found

      Example

      a = arr.array('i', [1, 2, 3, 2, 5, 6, 2, 9])
      c = a.index(2)
      print ("index of 2:", c)
      It will produce the following output
      index of 2: 1

      array.fromlist() Method

      The fromlist() method appends items from a Python list to the array object.

      Syntax

      array.fromlist(l)

      Parameters

      • i − The list, items of which are appended to the array. All items in the list must be of same arrtype.

      Example

      import array as arr
      a = arr.array('i', [1, 2, 3, 4, 5])
      lst = [6, 7, 8, 9, 10]
      c = a.fromlist(lst)
      print (a)
      It will produce the following output
      array('i', [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])

      array.tofile() Method

      The tofile() method in array class writes all items (as machine values) in the array to the file object f.

      Syntax

      array.tofile(f)

      Parameters

      • f − the file object obtained with open() function. The file to be opened in wb mode.

      Example

      import array as arr
      f = open('list.txt','wb')
      arr.array("i", [10, 20, 30, 40, 50]).tofile(f)
      f.close()

      Output

      After running the above code, a file named as "list.txt" will be created in the current directory.

      array.fromfile() Method

      The fromfile() method reads a binary file and appends specified number of items to the array object.

      Syntax

      array.fromfile(f, n)

      Parameters

      • f − The file object referring to a disk file opened in rb mode
      • n − number of items to be appended

      Example

      import array as arr
      a = arr.array('i', [1, 2, 3, 4, 5])
      f = open("list.txt", "rb")
      a.fromfile(f, 5)
      print (a)
      It will produce the following output 
      array('i', [1, 2, 3, 4, 5, 10, 20, 30, 40, 50])

      Practice with Online Editor

      Note: This Python online Editor is a Python interpreter written in Rust, RustPython may not fully support all Python standard libraries and third-party libraries yet.
      Remember to save code(Ctrl + S Or Command + S) before run it.