Question

我想找到给定字符串中的所有匹配项，包括重叠匹配项。我怎么能实现它？

# Example
"a-b-c".???(/\w-\w/)  # => ["a-b", "b-c", "c-d"] expected

# Solution without overlapped results
"a-b-c-d".scan(/\w-\w/) # => ["a-b", "c-d"], but "b-c" is missing

Answer 1

在积极前瞻中使用捕获：

"a-b-c-d".scan(/(?=(\w-\w))/).flatten
 # => ["a-b", "b-c", "c-d"]

请参阅Ruby demo

Answer 2

我建议使用非正则表达式解决方案：

from math import sin,cos,pi
def ellipse(pen, x, y, width, height):
    pen.penup()
    pen.goto(x + width / 2, height)
    pen.pendown()
    penX, penY = pen.pos()
    for i in range(0, 360):
        penX += cos(i*pi/180)*width/180
        penY += sin(i*pi/180)*height/180
        pen.goto(penX, penY)
    pen.penup()

或

"a-b-c-d".delete('-').each_char.each_cons(2).map { |s| s.join('-') }
  #=> ["a-b", "b-c", "c-d"]

或

"a-b-c-d".each_char.each_cons(3).select.with_index { |_,i| i.even? }.map(&:join)
  #=> ["a-b", "b-c", "c-d"]

找到重叠的正则表达式匹配

2 个答案: