python crypto square

python/crypto-square/.exercism/metadata.json

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+{"track":"python","exercise":"crypto-square","id":"627b6abfc585457083648a1c000bf0ab","url":"https://exercism.io/my/solutions/627b6abfc585457083648a1c000bf0ab","handle":"Xevion","is_requester":true,"auto_approve":false}

python/crypto-square/README.md

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+# Crypto Square
+
+Implement the classic method for composing secret messages called a square code.
+
+Given an English text, output the encoded version of that text.
+
+First, the input is normalized: the spaces and punctuation are removed
+from the English text and the message is downcased.
+
+Then, the normalized characters are broken into rows.  These rows can be
+regarded as forming a rectangle when printed with intervening newlines.
+
+For example, the sentence
+
+```text
+"If man was meant to stay on the ground, god would have given us roots."
+```
+
+is normalized to:
+
+```text
+"ifmanwasmeanttostayonthegroundgodwouldhavegivenusroots"
+```
+
+The plaintext should be organized in to a rectangle.  The size of the
+rectangle (`r x c`) should be decided by the length of the message,
+such that `c >= r` and `c - r <= 1`, where `c` is the number of columns
+and `r` is the number of rows.
+
+Our normalized text is 54 characters long, dictating a rectangle with
+`c = 8` and `r = 7`:
+
+```text
+"ifmanwas"
+"meanttos"
+"tayonthe"
+"groundgo"
+"dwouldha"
+"vegivenu"
+"sroots  "
+```
+
+The coded message is obtained by reading down the columns going left to
+right.
+
+The message above is coded as:
+
+```text
+"imtgdvsfearwermayoogoanouuiontnnlvtwttddesaohghnsseoau"
+```
+
+Output the encoded text in chunks that fill perfect rectangles `(r X c)`,
+with `c` chunks of `r` length, separated by spaces. For phrases that are
+`n` characters short of the perfect rectangle, pad each of the last `n`
+chunks with a single trailing space.
+
+```text
+"imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn  sseoau "
+```
+
+Notice that were we to stack these, we could visually decode the
+ciphertext back in to the original message:
+
+```text
+"imtgdvs"
+"fearwer"
+"mayoogo"
+"anouuio"
+"ntnnlvt"
+"wttddes"
+"aohghn "
+"sseoau "
+```
+
+## Exception messages
+
+Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to
+indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not
+every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include
+a message.
+
+To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
+`raise Exception`, you should write:
+
+```python
+raise Exception("Meaningful message indicating the source of the error")
+```
+
+## Running the tests
+
+To run the tests, run the appropriate command below ([why they are different](https://github.com/pytest-dev/pytest/issues/1629#issue-161422224)):
+
+- Python 2.7: `py.test crypto_square_test.py`
+- Python 3.4+: `pytest crypto_square_test.py`
+
+Alternatively, you can tell Python to run the pytest module (allowing the same command to be used regardless of Python version):
+`python -m pytest crypto_square_test.py`
+
+### Common `pytest` options
+
+- `-v` : enable verbose output
+- `-x` : stop running tests on first failure
+- `--ff` : run failures from previous test before running other test cases
+
+For other options, see `python -m pytest -h`
+
+## Submitting Exercises
+
+Note that, when trying to submit an exercise, make sure the solution is in the `$EXERCISM_WORKSPACE/python/crypto-square` directory.
+
+You can find your Exercism workspace by running `exercism debug` and looking for the line that starts with `Workspace`.
+
+For more detailed information about running tests, code style and linting,
+please see [Running the Tests](http://exercism.io/tracks/python/tests).
+
+## Source
+
+J Dalbey's Programming Practice problems [http://users.csc.calpoly.edu/~jdalbey/103/Projects/ProgrammingPractice.html](http://users.csc.calpoly.edu/~jdalbey/103/Projects/ProgrammingPractice.html)
+
+## Submitting Incomplete Solutions
+
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

python/crypto-square/crypto_square.py

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+import math, string
+
+def cipher_text(plain_text):
+    # Normalize the input
+    translation = str.maketrans({k : '' for k in string.punctuation})
+    plain_text = plain_text.translate(translation).replace(' ', '').lower()
+    if len(plain_text) == 0: return ''
+    # Calculate the dimensions of the crypto square (rectangle)
+    columns, matrix = math.ceil(math.sqrt(len(plain_text))), []
+    rows = math.ceil(len(plain_text) / columns)
+    for row in range(rows):
+        # Calculate the indexes
+        start, end = (row * columns), (row * columns) + columns
+        # Add pieces of the matrix, adding trailing space padding
+        matrix.append(plain_text[start:end].ljust(columns))
+    # Rotate the matrix so you can read by column
+    matrix = list(zip(*matrix))
+    return ' '.join(''.join(column) for column in matrix)

python/crypto-square/crypto_square_test.py

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+import unittest
+
+from crypto_square import cipher_text
+
+
+# Tests adapted from `problem-specifications//canonical-data.json` @ v3.2.0
+
+class CryptoSquareTest(unittest.TestCase):
+    def test_empty_string(self):
+        self.assertEqual(cipher_text(''), '')
+
+    def test_lowercase(self):
+        self.assertEqual(cipher_text('A'), 'a')
+
+    def test_remove_spaces(self):
+        self.assertEqual(cipher_text('  b '), 'b')
+
+    def test_remove_punctuation(self):
+        self.assertEqual(cipher_text('@1,%!'), '1')
+
+    def test_9chars_results_3chunks(self):
+        self.assertEqual(cipher_text('This is fun!'), 'tsf hiu isn')
+
+    def test_8chars_results_3chunks_ending_space(self):
+        self.assertEqual(cipher_text('Chill out.'), 'clu hlt io ')
+
+    def test_54chars_results_7chunks_2ending_space(self):
+        self.assertEqual(
+            cipher_text('If man was meant to stay on the ground, '
+                        'god would have given us roots.'),
+            'imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn  sseoau '
+        )
+
+
+if __name__ == '__main__':
+    unittest.main()