Ruby Quiz is Back - Challenge #1 - Read Comma-Separated Values (CSV) from the "Real World"

[Gerald Bauer]

Hello,
sorry for the false start of the Ruby Quiz. The Ruby Quiz is now
back for real.

Challenge #1 - Read Comma-Separated Values (CSV) from the "Real World"

Let's use the test.csv [1] 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

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 here on the "official" Ruby Quiz Channel,
that is, the ruby-talk mailing list :-).

Happy hacking and data wrangling with Ruby.

[1]: https://github.com/apache/commons-csv/blob/master/src/test/resources/CSVFileParser/test.csv

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[Dave Burt]

Dear Quizmaster,

Are there general guidelines like for the first Ruby Quiz (
http://rubyquiz.com/)?

Anyway, here is my brief entry.

#
# A simple solution using core String and Regexp features.
#
def parse( txt )
txt.each_line.map do |line|
next if line =~ /^#/ || line =~ /^\s+$/
line.strip.split(/\s*,\s*/, -1).map do |field|
field.sub(/^(['"])(.*)\1$/, '\\2')
end
end.compact
end

Cheers,
Dave

Post by Gerald Bauer
Hello,
sorry for the false start of the Ruby Quiz. The Ruby Quiz is now
back for real.
Challenge #1 - Read Comma-Separated Values (CSV) from the "Real World"
Let's use the test.csv [1] 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
```

[Gerald Bauer]

Hello,

Fantastic. Thanks for the great and brief example.

Post by Dave Burt
Dear Quizmaster,
Are there general guidelines like for the first Ruby Quiz (http://rubyquiz.com/)?

I'm Gerald - just a regular ruby-talk poster - no need for titles
:-). Welcome. Thanks for joining in.

Post by Dave Burt
Are there general guidelines like for the first Ruby Quiz (http://rubyquiz.com/)?

The new Ruby Quiz website is at Planet Ruby (
https://github.com/planetruby/quiz )

For now the only rule is that you have to pass the RubyQuizTest to qualify.

Cheers. Prost.

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[Gerald Bauer]

Hello,
For inspiration here's a snippet posted on the reddit ruby thread
[1]. Thanks to Paul.


class CSV include Mealy initial_state(:start) { @line = []; @text = ''
} read(state: :start, on: "\n") transition(from: :start, to: :comment,
on: '#') transition(from: :comment, to: :start, on: "\n") read(state:
:comment) transition from: [:normal, :start], to: :quote, on: '"'
transition from: :quote, to: :normal, on: '"' transition(from: :start,
to: :normal, on: ',') { @line << '' } transition(from: :start, to:
:normal, on: ' ') transition(from: :start, to: :normal) { |c| @text <<
c } transition(from: :normal, to: :start, on: "\n") do emit @line <<
@text; @line = []; @text = '' end read state: :normal, on: ' '
read(state: :normal, on: ',') { @line << @text; @text = '' }
read(state: [ :normal, :quote ]) { |c| @text << c } finish { emit
@line unless @line.empty? } end def parse(text)
CSV.new.run(text.chars).entries end


Happy hacking and data wrangling with Ruby.


[1] https://old.reddit.com/r/ruby/comments/9sbbt3/ruby_quiz_is_back_a_fortnightly_programming/

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[Gerald Bauer]

Hello,
sorry for the "minified" code snippet version for the Ruby Quiz #1.
Trying again (looks good in the email preview):

---
class CSV
include Mealy

initial_state(:start) { @line = []; @text = '' }

read(state: :start, on: "\n")

transition(from: :start, to: :comment, on: '#')
transition(from: :comment, to: :start, on: "\n")
read(state: :comment)


transition from: [:normal, :start], to: :quote, on: '"'
transition from: :quote, to: :normal, on: '"'

transition(from: :start, to: :normal, on: ',') { @line << '' }
transition(from: :start, to: :normal, on: ' ')
transition(from: :start, to: :normal) { |c| @text << c }
transition(from: :normal, to: :start, on: "\n") do
emit @line << @text; @line = []; @text = ''
end

read state: :normal, on: ' '
read(state: :normal, on: ',') { @line << @text; @text = '' }

read(state: [ :normal, :quote ]) { |c| @text << c }

finish { emit @line unless @line.empty? }
end

def parse(text)
CSV.new.run(text.chars).entries
end
---


Happy hacking and data wrangling with Ruby.

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[Frank J. Cameron]

Post by Gerald Bauer
Challenge #1 - Read Comma-Separated Values (CSV) from the "Real World"

$ ruby lib/1.rb
Run options: --seed 19056
# Running:
.
Finished in 0.002289s, 436.9176 runs/s, 436.9176 assertions/s.
1 runs, 1 assertions, 0 failures, 0 errors, 0 skips

$ cat lib/1.rb
require_relative '../test/1.rb'
class RubyQuizTest
def parse(text)
text.lines.map do |line|
next if line.match(/^\s*$|#/)
line.strip.split(/\s*,\s*/, -1)
end.compact.map do |cells|
cells.map do |cell|
cell.match(/"(.*)"/) ? $1 : cell
end
end
end
end
RubyQuizTest.new('fjc')



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