Evaluating Ruby regex and variables

Question

This will seem like an odd problem to have. I've got this bit of Ruby code that takes an input string, uses scan and flatten to extract a particular value, and the hope is to then operate off that value in an if...then statement, but I'm having issues.

My input string describes the number of 'dangerous creatures' in the area. The string, when describing no dangerous creatures or two or more creatures is always standard, something like:

"no dangerous creatures in the area" or "one dangerous creature..." and so on.

I'm using this to fetch the word representing the number of creatures as: "no", "one", "two", and so on in hopes of converting these to numeric values later on - "no" = 0, "one" = 1, etc.

To do this, I use:

crittercount = strcheck.scan(/a*(no|one|two|three|four|five|six|seven|eight|nine|ten)a*/)

Then I go and do an if then on the variable crittercount saying:

if crittercount == "no"
  critters = 0
  ... exit and go do something with the var...
end

I do this for each one. (when I get this issue figured out I'll use if..elsif..end)

if crittercount == "one"
  critters = 1
  ... exit and go do something with the var...
end
...

After crittercount == "ten" I just use

if crittercount == "ten"
  critters = 10
else
  critters = 99
end

Here is the problem: I have a variable called maxcreatures equal to 10. I take the strcheck value of "no dangerous creatures in the area" for example, I print out the value it returns that exact string. Then I print out the crittercount variable, in this example, I get "no".

When I get through my if..then.. statements though, I evaluate what to do using:

if critters > maxcreatures
  print "Maximum Creatures " + critters.to_s + " and maximum is #{maxcreatures}.  Lets Bail"
else
  print "Critter count " + critters.to_s  + " is less than #{maxcritters} Keep going."
end

In every situation I'm getting 99 and I swear I've tried everything. I tried using .flatten at the end of the regex, I tried using .strip on the crittercount var. I'm hoping someone looks at this and goes 'duh, try this.'

On request here is all the code, there are calls in here to other functions that may not make sense...

maxcritters = 2

critters = 0


put "count critter"
strcheck = matchfind "You notice ?"

crittercount = strcheck.scan(/a*(no|one|two|three|four|five|six|seven|eight|nine|ten)a*/)
echo strcheck
echo crittercount
crittercount = crittercount.strip
if crittercount == "no"
    critters = 0
    goto "roundup"
end
if crittercount  == "one"
    critters = 1
    goto "roundup"
end
if crittercount == "two"
    critters = 2
    goto "roundup"
end
if crittercount == "three"
    critters = 3
    goto "roundup"
end
if crittercount == "four"
    critters = 4
    goto "roundup"
end
if crittercount == "five"
    critters = 5
    goto "roundup"
end
if crittercount == "six"
    critters = 6
    goto "roundup"
end
if crittercount == "seven"
    critters = 7
else
critters = 99
end

roundup:
if critters > maxcritters
echo "Maximum Creatures " + critters.to_s + " and maximum is #{maxcritters}.  Lets Bail"
critters == nil
fput "retreat"

else
    echo "Critter count " + critters.to_s  + " is below maximum of #{maxcritters} - We're cool.  Keep going."
    critters == nil
    goto "combatcheck"
end

I was hoping to avoid that as there are calls to Ruby functions outside the scope of it, but I'll ad it to the main question. — user401093
– user401093, Commented Oct 24, 2012 at 12:13
What is the a* that you have in the regex? That seems to be part of the reason for your problem. — sawa
– sawa, Commented Oct 24, 2012 at 12:21

sawa · Accepted Answer · 2012-10-24 12:33:09Z

1

scan is useful when you might expect multiple matches. Since you only expect one match per string, you should not use that.

The following will directly give you critters. You don't need all those conditionals.

regex = /(\bno\b)|(\bone\b)|(\btwo\b)|(\bthree\b)|(\bfour\b)|(\bfive\b)
            |(\bsix\b)|(\bseven\b)|(\beight\b)|(\bnine\b)|(\bten\b)/x

critters = strcheck.match(regex).to_a.drop(1).index{|x| x} || 99

answered Oct 24, 2012 at 12:33

sawa

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Comments

Mischa · Accepted Answer · 2012-10-24 12:24:55Z

0

The problem is that crittercount is an array, not a string. Therefore if crittercount == "no" etc. will never be true and you will always end up in your last else.

Solution is to change your code to:

crittercount = strcheck.scan(/no|one|two|three|four|five|six|seven|eight|nine|ten/).first

With this crittercount will be either a string or nil and the rest of your code will work as expected.

edited Oct 24, 2012 at 12:24

answered Oct 24, 2012 at 12:19

Mischa

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1 Comment

Mischa Over a year ago

You're welcome. My answer just shows why your code didn't work. It doesn't mean this is the best solution. The other answers have very good suggestions to drastically shorten your code. You don't need all those if...ends.

Doon · Accepted Answer · 2012-10-24 12:36:57Z

0

scan returns an array, containing and array of match data, so in your code if you called .first.first you would get at the first match. you can also do something like this

strcheck = "two dangerous creatures in the area" # or "one dangerous creature...'
strcheck =~ (/(.*) dangerous.*/)
critters = case $1 
  when 'no' then 0
  when 'one' then 1
  when 'two' then 2
  when 'three' then 3
  when 'four' then 4
  when 'five' then 5
  when 'six' then 6
  when 'seven' then 7
  else 99 
end
puts "number of critters #{critters}"

using the case cleans up the logic, and just use the regex to match and extract the first match

answered Oct 24, 2012 at 12:36

Doon

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Comments

Alan · Accepted Answer · 2012-10-24 12:44:37Z

It looks like you are doing if...end if...end if...end rather than if...elsif..elsif...end

So for any value other than 10, you are going to end up in this else block

if crittercount == "ten"
  critters = 10
else
  critters = 99
end

A case statement would be better here...

case (crittercount)
    when "no" then critters = 0
    when "one" then critters = 1
    when "two" then critters = 2
    when "three" then critters = 3
    when "four" then critters = 4
    when "five" then critters = 5
    when "six" then critters = 6
    when "seven" then critters = 7
    when "eight" then critters = 8
    when "nine" then critters = 9
    when "ten" then critters = 10
    else critters = 99
end

Or even better, a hash lookup for all the numbers that defaults to 99 if the lookup fails.

numberHash = { "no" => 0, "one" => 1, "two" => 2, "three" => 3, "four" => 4, "five" => 5, "six" => 6, "seven" => 7, "eight" => 8, "nine" => 9, "ten" => 10 }
numberHash.default = 99
critters = numberHash[critterCount]

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