Ruby Quiz

Ruby Quiz - Challenge #1 - Read Comma-Separated Values (CSV) from the “Real World”

Let’s use the test.csv file from Apache Commons CSV Reader. The challenge: Code a parse method that passes the RubyQuizTest :-). Start from scratch or, yes, use any library / gem you can find.

def parse( txt )
  # ...
end

To qualify for solving the code challenge / puzzle you must pass the test:

require 'minitest/autorun'


class RubyQuizTest < MiniTest::Test

  def test_parse   # level 1

    records = [["A", "B", "C", "D"],
              ["a", "b", "c", "d"],
              ["e", "f", "g", "h"],
              [" i ", " j ", " k ", " l "],
              ["", "", "", ""],
              ["", "", "", ""]]


    assert_equal records, parse( <<TXT )
A,B,C,"D"
# plain values
a,b,c,d
# spaces before and after
 e ,f , g,h
# quoted: with spaces before and after
" i ", " j " , " k "," l "
# empty values
,,,
# empty quoted values
"","","",""
# 3 empty lines



# EOF on next line
TXT

  end # method test_parse
end # class RubyQuizTest

Post your code snippets on the “official” Ruby Quiz Channel, that is, the ruby-talk mailing list.

Bonus: Let’s Add Three More Difficulty Levels

Level 2 - Commas Inside Quotes and Double Up Quotes in Quotes

Let’s turn Shakespeare’s “literal” Hamlet quote:

Hamlet says, "Seems," madam! Nay it is; I know not "seems."

into

1, "Hamlet says, ""Seems,"" madam! Nay it is; I know not ""seems."""

And the test reads:

def test_parse_level2
  records = [["1", "Hamlet says, \"Seems,\" madam! Nay it is; I know not \"seems.\""]]

  assert_equal records, parse( <<TXT )
1, "Hamlet says, ""Seems,"" madam! Nay it is; I know not ""seems."""
TXT
end

Level 3 - Unix/Ruby-Style Backslash Escapes

Lets add the “unix-style” escaping with backslashes (e.g. \" for "") used by Ruby :-), PostgreSQL, MySQL and others (when exporting database tables in CSV, for example):

1, "Hamlet says, \"Seems,\" madam! Nay it is; I know not \"seems.\""

And the test reads:

def test_parse_level3
  records = [["1", "Hamlet says, \"Seems,\" madam! Nay it is; I know not \"seems.\""]]

  assert_equal records, parse( <<TXT )
1, "Hamlet says, \\"Seems,\\" madam! Nay it is; I know not \\"seems.\\""
TXT
end

Level 4 - Single or Double? Mixed Quotes

Let’s again get inspired by Ruby :-) - see 210 Ways to Rome and lets add single or double quotes.

1, "Hamlet says, 'Seems,' madam! Nay it is; I know not 'seems.'"
2, 'Hamlet says, "Seems," madam! Nay it is; I know not "seems."'

And the test reads:

def test_parse_level4
  records = [["1", "Hamlet says, 'Seems,' madam! Nay it is; I know not 'seems.'"],
             ["2", 'Hamlet says, "Seems," madam! Nay it is; I know not "seems."']]

  assert_equal records, parse( <<TXT )
1, "Hamlet says, 'Seems,' madam! Nay it is; I know not 'seems.'"
2, 'Hamlet says, "Seems," madam! Nay it is; I know not "seems."'
TXT
end

Happy hacking and data wrangling with Ruby.

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