CODEWITHSUNDEEP
ruby-on-railsrubyruby-on-rails-3rubygems
me24hour
me24hour

Reputation: 719

Discarding everything in a string variable after the second decimal

I have a Ruby string variable with the value 1.14.2.ab3-4.dl0.rhel However, I want to discard everything after the second decimal so that I get the value as 1.14

I am using the following command: str.split(".")[0] but it doesn't seem to work

Upvotes: 1

Views: 79

Answers (4)

Cary Swoveland
Cary Swoveland

Reputation: 110755

@maxple's answer only works when the substring of interest is at the beginning of the string. As that was not part of the specification (only in the example), I don't think that's a reasonable assumption. (@Eric did not make that assumption.)

There is also ambiguity about your statement, "discard everything after the second decimal". @maxple interpreted that as after the second decimal point (but also discarded the second decimal point), whereas @Eric assumed it meant after the second decimal digit. This is what happens when questions are imprecise.

If the substring is at the beginning of the string, and you mean to discard the second decimal point and everything after, here are two ways to do that.

str = "1.14.2.ab3-4.dl0.rhel"

1. Modify @Eric's regex:

str[/\A\d+\.\d+/]
   #=> "1.14"

2. Convert the string to a float and then back to a string:

str.to_f.to_s
  #=> "1.14"

#1 returns nil if the desired substring does not exist, whereas #2 returns "0.0". As long as "0.0" is not a valid substring, either can be used to determine if the substring exists, and if it does, return the substring.

Upvotes: 1

rii
rii

Reputation: 1658

You could also use the partition method in String: https://ruby-doc.org/core-2.2.0/String.html#method-i-partition

"1.14.2.ab3-4.dl0.rhel".partition(/\d+\.\d{2}/)[1]
=> "1.14"

Upvotes: 0

Eric Duminil
Eric Duminil

Reputation: 54303

With a regexp, you could just look for the first number with 2 decimals : 

"1.14.2.ab3-4.dl0.rhel"[/\d+\.\d{2}/]
#=> "1.14"

Upvotes: 2

max pleaner
max pleaner

Reputation: 26788

When you split by . on your string you get:

['1', '14', '2', 'ab3-4', 'dl0', 'rhel']

From this you can get the first two items joined by period:

str.split(".")[0..1].join(".")

# or
str.split(".").first(2).join(".")

Upvotes: 3

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