# Python | Encoding Decoding using Matrix

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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