I like to know the number of 0's which are surrounded by 1. But if there are more than one 0 without interrupted by a 1 it count only as one.
我想知道被1包围的0的数量。但是如果有多个0而没有被1中断,它只计为1。
string <- "1101000010101111001110"
This is the closest I'm able to do:
这是我能做的最接近的事情:
length(gregexpr(pattern ="101",string)[[1]])
Expected output:
5
1 个解决方案
#1
9
With gregexpr you can use lookahead assertion with perl=True to find overlapping matches:
使用gregexpr,你可以使用perl = True的lookahead断言来查找重叠匹配:
(?=...) is a lookahead assertion:
(?= ...)是一个先行断言:
(?=...)A zero-width positive lookahead assertion. For example,
/\w+(?=\t)/matches a word followed by a tab, without including the tab in$&.零宽度正向前瞻断言。例如,/ \ w +(?= \ t)/匹配单词后跟选项卡,而不包括$&中的选项卡。
length(gregexpr("(?=10+1)", string, perl=TRUE)[[1]])
#1
9
With gregexpr you can use lookahead assertion with perl=True to find overlapping matches:
使用gregexpr,你可以使用perl = True的lookahead断言来查找重叠匹配:
(?=...) is a lookahead assertion:
(?= ...)是一个先行断言:
(?=...)A zero-width positive lookahead assertion. For example,
/\w+(?=\t)/matches a word followed by a tab, without including the tab in$&.零宽度正向前瞻断言。例如,/ \ w +(?= \ t)/匹配单词后跟选项卡,而不包括$&中的选项卡。
length(gregexpr("(?=10+1)", string, perl=TRUE)[[1]])