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# Python | Encoding Decoding using Matrix

• Last Updated : 30 Dec, 2020

Encoding process :

1. Take a String convert to corresponding number shown below 2. convert to 2D matrix(array). Now we have 2×2 matrix!
3. When we multiply this matrix with encoding matrix we get encoded 2×2 matrix.
4. now convert to vector(1D array) and Display to user

Decoding process

• Take Encoded number convert into 2D matrix(array)
• Inverse Encoding matrix!
• Multiply Encoded matrix with inverse of encoding matrix.
• convert to 1D Matrix(array).then convert to corresponding Alphabets. ### Code : Encode.py

 `# loading libraries``import` `numpy as np`` ` `a  ``=`  `[``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``]``c  ``=`  `[[``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``],``       ``[``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``,``0``]]`` ` `# encode matrix``ecm ``=` `[[``3``,``4``], [``3``,``6``]]``i ``=` `0``l ``=` `0``  ` `# Lists of Alphabets and its values``smallalpha ``=` `[``" "``,``"a"``, ``"b"``, ``"c"``, ``"d"``, ``"e"``, ``"f"``, ``"g"``, ``"h"``,``              ``"i"``, ``"j"``, ``"k"``, ``"l"``, ``"m"``, ``"n"``, ``"o"``, ``"p"``, ``"q"``,``              ``"r"``, ``"s"``, ``"t"``, ``"u"``, ``"v"``, ``"w"``, ``"x"``, ``"y"``, ``"z"``]``capitalalpha ``=` `[``" "``,``"A"``, ``"B"``, ``"C"``, ``"D"``, ``"E"``, ``"F"``, ``"G"``, ``"H"``,``                ``"I"``, ``"J"``, ``"K"``, ``"L"``, ``"M"``, ``"N"``, ``"O"``, ``"P"``, ``"Q"``,``                ``"R"``, ``"S"``, ``"T"``, ``"U"``, ``"V"``, ``"W"``, ``"X"``, ``"Y"``, ``"Z"``]``alphavalues ``=` `[``0``, ``1``, ``2``, ``3``, ``4``, ``5``, ``6``, ``7``, ``8``, ``9``, ``10``, ``11``, ``12``,``               ``13``, ``14``, ``15``, ``16``, ``17``, ``18``, ``19``, ``20``, ``21``, ``22``,``               ``23``, ``24``, ``25``, ``26``, ``27``]`` ` `# string to convert ``b ``=` `"India"``listb ``=` `list``(b)``lenb ``=` `len``(listb)``  ` `# Loop to convert Word to Values that ``# are further useful for Encoding``for` `i ``in` `range``(lenb):``    ``for` `j ``in` `range``(``27``):``        ``if``(listb[i]  ``=``=` `smallalpha[j]):``            ``a[i] ``=` `alphavalues[j]``            ``if``(j  ``=``=` `23``):``                ``j ``=` `0``            ``break``        ``if``(j  ``=``=` `23``):``            ``for` `k ``in` `range``(``27``):``                ``if``(listb[i]  ``=``=` `capitalalpha[k]):``                    ``a[i] ``=` `alphavalues[k]``                    ``break``                    ` `                  ` `if``(lenb``%``2` `=``=` `1``):``    ``lenb ``=` `lenb``+``1``a ``=` `a[``0``:lenb]``tb ``=` `b``  ` `  ` `# convert this array to 2D array for further ``# multiplication with encoding matrix`` ` `j ``=` `0``k ``=` `0`` ` `# b[m][n] m is always 2``n ``=` `int``(lenb``/``2``)``for` `i ``in` `range``(``0``,lenb):``    ``if``(j

Time Complexity : O(n)(where n is length of message)
Space Complexity : O(n)

Output:

```Encoding matrix =  [[3, 4], [3, 6]]
Encrypted form =  [63, 46, 12, 81, 48, 12]
```

### Code : Decode.py

 `# importing libraries``import` `numpy as np``from` `numpy.linalg ``import` `inv`` ` ` ` `# Initial values``a ``=``[``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``,``    ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``]`` ` `tdm ``=``[[``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``], ``      ``[``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``, ``0``]]`` ` `# encoding matrix``ecm ``=``[[``3``, ``4``],``     ``[``3``, ``6``]]`` ` `# Lists of Alphabets and its values``smallalpha ``=` `[``" "``,``"a"``, ``"b"``, ``"c"``, ``"d"``, ``"e"``, ``"f"``, ``"g"``, ``"h"``,``              ``"i"``, ``"j"``, ``"k"``, ``"l"``, ``"m"``, ``"n"``, ``"o"``, ``"p"``, ``"q"``,``              ``"r"``, ``"s"``, ``"t"``, ``"u"``, ``"v"``, ``"w"``, ``"x"``, ``"y"``, ``"z"``]``capitalalpha ``=` `[``" "``,``"A"``, ``"B"``, ``"C"``, ``"D"``, ``"E"``, ``"F"``, ``"G"``, ``"H"``,``                ``"I"``, ``"J"``, ``"K"``, ``"L"``, ``"M"``, ``"N"``, ``"O"``, ``"P"``, ``"Q"``,``                ``"R"``, ``"S"``, ``"T"``, ``"U"``, ``"V"``, ``"W"``, ``"X"``, ``"Y"``, ``"Z"``]``alphavalues ``=` `[``0``, ``1``, ``2``, ``3``, ``4``, ``5``, ``6``, ``7``, ``8``, ``9``, ``10``, ``11``, ``12``,``               ``13``, ``14``, ``15``, ``16``, ``17``, ``18``, ``19``, ``20``, ``21``, ``22``,``               ``23``, ``24``, ``25``, ``26``, ``27``]`` ` ` ` `# Take inputs``# elements in Encrypted Matrix``lenb ``=` `6``a ``=` `[``63``, ``46``, ``12``, ``81``, ``48``, ``12``]`` ` `sobj ``=` `slice``(lenb)``a ``=` `a[sobj]`` ` ` ` `# convert array to 2d matrix to further ``# multiplication with inverse of 2d matrix``j ``=` `0``k ``=` `0`` ` `# b[m][n] m is always 2``n ``=` `int``(lenb ``/` `2``)``for` `i ``in` `range``(``0``, lenb):``    ``if``(j

Time Complexity :
O(n)(where n is number of elements)
Space Complexity : O(n)

Output:

`Decoded message = india `

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