OCR Numbers

Instructions

Optical Character Recognition or OCR is software that converts images of text into machine-readable text. Given a grid of characters representing some digits, convert the grid to a string of digits. If the grid has multiple rows of cells, the rows should be separated in the output with a ",".

• The grid is made of one of more lines of cells.
• Each line of the grid is made of one or more cells.
• Each cell is three columns wide and four rows high (3x4) and represents one digit.
• Digits are drawn using pipes ("|"), underscores ("_"), and spaces (" ").

Edge cases

• If the input is not a valid size, your program should indicate there is an error.
• If the input is the correct size, but a cell is not recognizable, your program should output a "?" for that character.

Examples

The following input (without the comments) is converted to "1234567890".

      _  _     _  _  _  _  _  _  #
    | _| _||_||_ |_   ||_||_|| | # Decimal numbers.
    ||_  _|  | _||_|  ||_| _||_| #
                                 # The fourth line is always blank,

The following input is converted to "123,456,789".

    _  _ 
  | _| _|
  ||_  _|
         
    _  _ 
|_||_ |_ 
  | _||_|
         
 _  _  _ 
  ||_||_|
  ||_| _|
         

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Source

Inspired by the Bank OCR kata