Ruby 删除以特定字符开头的所有子字符串

Question

我想删除字符串中以井号开头并以 space 结尾或位于字符串末尾的所有子字符串。我有一个有效的解决方案，但我想知道是否有更有效（或同样有效但不那么冗长）的方法。

比如我想把"leo is #confused about #ruby #gsub"变成"#confused #ruby #gsub".

这是我目前的解决方案，其中涉及数组和减法。

strip_spaces = str.gsub(/\s+/, ' ').strip()
  => "leo is #confused about #ruby #gsub"
all_strings = strip_spaces.split(" ").to_a
  => ["leo", "is", "#confused", "about", "#ruby", "#gsub"]
non_hashtag_strings = strip_spaces.gsub(/(?:#(\w+))/) {""}.split(" ").to_a
  => ["leo", "is", "about"]
hashtag_strings = (all_strings - non_hashtag_strings).join(" ")
  => "#confused #ruby #gsub"

老实说，既然我写完了这个问题，我通过 research/experimentation 学到了一些东西，并且对这种数组方法更加熟悉。但我仍然想知道是否有人可以推荐改进。

Answer 1

你可以试试这个

string.split(' ').select { |e| e.start_with?("#") }.join(' ')

说明

split - 根据分隔符将字符串分成子字符串数组，在本例中为 space

select - 用于过滤匹配传入表达式

的数组

|e| e.start_with?("#") - 仅查找以井号开头的子字符串

join(' ') - 用于将数组转换回字符串

Answer 2

我会这样做：

string = "leo is #confused about #ruby #gsub"
#=> "leo is #confused about #ruby #gsub"
string.split.select { |word| word.start_with?('#') }.join(' ')
#=> "#confused #ruby #gsub"

Answer 3

仅正则表达式解决方案

string = "leo is #confused about #ruby #gsub"
string.scan(/#\w+/)
#  => ["#confused", "#ruby", "#gsub"]

如果您希望在单词中包含 # 符号，则正则表达式稍微复杂：

string = "leo is #confused ab#out #ruby #gsub"
string.scan(/(?<=\s)#\w+/)
#  => ["#confused", "#ruby", "#gsub"]

Answer 4

总是有更多方法给猫剥皮

s = "leo is #confused about #ruby #gsub"
#sub all the words that do not start with a #
s.gsub(/(?<=^|\s)#\w+\s?/,'')
#=> "#confused #ruby #gsub"
#split to Array and grab all the strings that start with #
s.split.grep(/\A#/).join(' ')
#=> "#confused #ruby #gsub"
#split to Array and separate them into 2 groups
starts_with_hash,others = s.split.partition {|e| e.start_with?('#') }
#=>[["#confused", "#ruby", "#gsub"], ["leo", "is", "about"]]
starts_with_hash.join(' ') 
#=> "#confused #ruby #gsub"

fruity

提供的这些和其他答案的基准测试

require 'fruity'

def split_start_with(s)
    s.split.select {|e| e.start_with?("#")}.join(' ')
end

def with_scan(s)
    s.scan(/#\w+/).join(' ')
end

def with_gsub(s)    
  s.gsub(/(?<=^|\s)#\w+\s?/,'')
end

def split_grep(s)
    s.split.grep(/\A#/).join(' ')
end

str = "This is a reasonable string #withhashtags where I want to #test multiple #stringparsing #methods for separating and joinging #hastagstrings together for #speed"

compare do 
  split_start_with_test {split_start_with(str)}
  with_scan_test {with_scan(str)}
  with_gsub_test {with_gsub(str)}
  split_grep_test {split_grep(str)}
end

结果：

Running each test 262144 times. Test will take about 5 minutes.
split_start_with_test is similar to with_scan_test
with_scan_test is faster than with_gsub_test by 60.00000000000001% ± 1.0%
with_gsub_test is faster than split_grep_test by 30.000000000000004% ± 1.0%

Ruby 删除以特定字符开头的所有子字符串

Ruby remove all substrings that begin with specific character

ruby

gsub