How to split text in Ruby without creating empty strings?

Question

Splitting on whitespace, period, comma or double quotes, and not on single quotes:

str = %Q{this is the.string    to's split,real "ok" nice-like.}
str.split(/\s|\.|,|"/)
=> ["this", "is", "the", "string", "", "", "", "to's", "split", "real", "", "ok", "", "nice-like"]

How to eloquently remove empty strings?

How to eloquently remove strings that are shorter than MIN_LENGTH?

sawa · Accepted Answer · 2012-03-15 05:22:11Z

8

The idea of using split is not right in this case. You should be using scan.

str = %Q{this is the.string    to's split,real "ok" nice-like.}
str.scan(/[\w'-]+/)
# => ["this", "is", "the", "string", "to's", "split", "real", "ok", "nice-like"]

In order to match strings that are MIN_LENGTH or longer, do like this:

MIN_LENGTH = 3
str.scan(/[\w'-]{#{MIN_LENGTH},}/)
# => ["this", "the", "string", "to's", "split", "real", "nice-like"]

When to use split, when to use scan

When the delimiters are messy and making a regex match them is difficult, use scan.
When the substrings to extract are messy and making a regex match them is difficult, use split.
When you want to impose conditions on the form of the substrings to be extracted, you scan.
When you want to impose conditions on the form of the delimiters, use split.

edited Mar 15, 2012 at 5:22

answered Mar 15, 2012 at 5:14

sawa

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2 Comments

B Seven Over a year ago

This is actually much better for what I was trying to do. split is not good because you have to figure out all the other possible delimiters, like !, --, ?, ~, :, etc.

B Seven Over a year ago

Tobias answered the first question best: str.split /[\s\.,"]+/

Tobias Cohen · Accepted Answer · 2012-03-15 04:12:41Z

8

I'm not entirely clear on the problem domain, but if you just want to avoid the empty strings, why not split on one or more occurrences of your separators?

str.split /[\s\.,"]+/

answered Mar 15, 2012 at 4:12

Tobias Cohen

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Comments

Nikhil · Accepted Answer · 2012-03-15 03:38:37Z

6

I would think a simple way to do that is as follows:

str.split(/\s|\.|,|"/).select{|s| s.length >= MIN_LENGTH}

answered Mar 15, 2012 at 3:38

Nikhil

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1 Comment

B Seven Over a year ago

Works and easy to understand.

xdazz · Accepted Answer · 2012-03-15 03:40:37Z

2

Try the below:

str.split(/\s*[.,"\s]\s*/)

answered Mar 15, 2012 at 3:40

xdazz

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Comments

nkm · Accepted Answer · 2012-03-15 05:23:38Z

2

We can achieve the same in multiple ways,

 > str.split(/[\s\.,"]/) - [""]
=> ["this", "is", "the", "string", "to's", "split", "real", "ok", "nice-like"]

 > str.split(/[\s\.,"]/).select{|sub_string| sub_string.present?}
=> ["this", "is", "the", "string", "to's", "split", "real", "ok", "nice-like"]

 > str.scan /\w+'?\w+/
=> ["this", "is", "the", "string", "to's", "split", "real", "ok", "nice", "like"]

answered Mar 15, 2012 at 5:23

nkm

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Kyle · Accepted Answer · 2012-03-15 03:38:56Z

1

MIN_LENGTH = 2

new_strings = str.split(/\s|\.|,|"/).reject{ |s| s.length < MIN_LENGTH }

answered Mar 15, 2012 at 3:38

Kyle

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