Question

我想从字符串中删除所有子字符串，这些子字符串以井号开头并以空格结尾或位于字符串的末尾。我有一个有效的解决方案，但我想知道是否有更高效（或同样有效但不那么罗嗦）的方法。

例如，我想将"leo is #confused about #ruby #gsub"转为"#confused #ruby #gsub"。

这是我现在的解决方案，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"

说实话，既然我已经写完了这个问题，我已经通过研究/实验学到了一些东西，并且对这种阵列方法变得更加自如。但我仍然想知道是否有人可以推荐改进。

Answer 1

我会做这样的事情：

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 2

仅限Regexp解决方案

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

如果您希望单词中包含#符号，则正则表达式稍微复杂一些：

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

Answer 3

总是有更多方法给猫皮肤

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%

Answer 4

你可以试试这个

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

解释

split - 根据分隔符将字符串分解为子字符串数组，在本例中为空格

select - 用于过滤与传入的表达式

匹配的数组

|e| e.start_with?("#") - 仅查找以井号开头的子串

join(' ') - 用于将数组转换回字符串

Ruby删除所有以特定字符开头的子字符串

4 个答案: