Christmas Puzzler 2021: Text Scrambler / Descrambler

The Problem

Parameters: text: a text string amount: 0.0 ... 1.0

Scramble should rearrange the letters within words, not across them. Whitespace and punctuation should be preserved in place.

The amount means:

• 0: no change
• otherwise, a higher number is more scrambled

My Solution

In this implementation, for each word there are ⌈ length(word) * amount * 0.5 ⌉ letter swaps in the word, and each occurrence of a word gets the same scrambling (although capitalization and punctuation are seen as a new word).

To run the scrambler, provide amount, in-file, out-file:

$ time poetry run python -m puzzler.scramble 0.5 data/books/84-0.txt test.txt

real	0m0.391s
user	0m0.358s
sys	0m0.032s

$ time poetry run python -m puzzler.descramble test.txt test-undo.txt

real	0m1.430s
user	0m1.361s
sys	0m0.070s

$ wc data/books/84-0.txt test.txt test-undo.txt
   7743   78122  448821 data/books/84-0.txt
   7743   78122  441078 test.txt
   7743   78122  441008 test-undo.txt
  23229  234366 1330907 total

(The character difference is down to whitespace changes.)

Data Not In Repo

The descrambler uses a word frequency table in data/external/unigram_freq.csv.zip downloaded from Kaggle English Word Frequency derived from the Google Web Trillion Word Corpus.

The test book is Frankenstein, from Gutenberg.

Sample Input / Output

The first paragraph of Frankenstein is

You will rejoice to hear that no disaster has accompanied the commencement of an enterprise which you have regarded with such evil forebodings. I arrived here yesterday, and my first task is to assure my dear sister of my welfare and increasing confidence in the success of my undertaking.

Scrambled at an amount of 1 gives

You wlil irejeoc ot rhea taht on iedstsra sah acmcdapnioe teh omectmecenmn fo na netrerepsi cihwh oyu haev rdegeard with such liev soifrodbeng. I aervidr eehr ysredtaye, dan ym rftis astk si ot suraes ym edra sisrte fo ym fealrwe dan neiciansgr cfdonciene ni teh uscscse fo ym utinnedrakg.

Descrambled gives

You will rejoice to hear that no disaster has accompanied the commencement of an enterprise which you have regarded with such evil forebodings. I arrived here yesterday, and my first task is to assure my read sister of my welfare and increasing confidence in the success of my undertaking.