How do I convert a string to an array with spaces preserved in Ruby?-CodePudding

How do I convert a String: 'Hello world!' to an array: ['Hello', ' ', 'world!'] with all spaces preserved?

I tried to convert the string using the split method with different parameters, but I didn't find the right solution.

Also I didn't find any other method in the documentation (Class: String (Ruby 3.1.0)) suitable for solving this problem.

CodePudding user response：

It just occured to me, that you could use scan. Assuming that your string is stored in the variable s, and you want to separate space regions and non-space regions, you could do a

s.scan(/[ ] |[^ ] /)

which would yield in your case

["Hello", "   ", "world!"]

CodePudding user response：

Use String#scan Instead of String#split

You don't want to use String#split because that won't preserve your spaces. You want to use String#scan or String#partition instead. Using Unicode character properties, you can scan for matches with:

'Hello   world!'.scan /[\p{Alnum}\p{Punct}] |\p{Space} /
#=> ["Hello", "   ", "world!"]

You can also use POSIX character classes (pronounced "bracket expressions" in Ruby) to do the same thing if you prefer. For example:

'Hello   world!'.scan /[[:alnum:][:punct:]] |[[:space:]] /
#=> ["Hello", "   ", "world!"]

Either of these options will be more robust than solutions that rely on ASCII-only characters or literal whitespace atoms, but if you know your strings won't include other types of characters or encodings then those solutions will work too.

Using String#partition

For the very simple use case in your original example, you only have two words separated by whitespace. That means you can also use String#partition to partition on the sequential whitespace. That will split the string into exactly three elements, preserving the whitespace that partitions the words. For example:

'Hello   world!'.partition /\s /
#=> ["Hello", "   ", "world!"]

While simpler, the partitioning approach won't work as well with longer strings such as:

'Goodbye   cruel world!'.partition /\s /
#=> ["Goodbye", "   ", "cruel world!"]

so String#scan is going to be a better and more flexible approach for the general use case. However, anytime you want to split a string into three elements, or to preserve the partitioning element itself, #partition can be very handy.