• What is autocorrect?
  • Building the model
  • Minimum Edit Distance
  • Minimun Edit Distance Algorithm


Application that changes mispelled words to the correct ones.

  1. Indentify a misspelled word
  2. Find strings n edit distance away
  3. Filter candidates
  4. Calculate word probabilities

Building the model

  1. You know misspelled words by looking into a dictionary.
  2. Edit Distance takes into consideration 3 operations:
    • Insert (add a letter)
    • Delete (remove a letter)
    • Switch (swap two neighbor letter)
    • Replace (replacing a letter)
  3. Filter candidates looking into the dictionary

Building the model II

  1. Calculate the word probabilities
\[P(w) = \frac{C(w)}{V}\]

Minimum edit distance

The lowest number to transform one string to another

Minimum edit distance algorithm

\[D[i,j] = \left\{ \begin{array}{lc} D[i-1, j] + del\_cost \\ D[i, j-1] + ins\_cost \\ D[i-1, j-1] + \left\{ \begin{array}{rr} rep\_cost; if scr[i] \neq tar[j] \\ 0; if scr[i] = tar[j] \end{array} \right . \end{array} \right .\]

Ungraded Lab: Building the vocabulary

Notebook / HTML

Ungraded Lab: Candidates from edits

Notebook / HTML

Programming Assignment: Autocorrect

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