将求和应用于二进制向量 [英] Applying cumsum to binary vector

问题描述

我有一个简单的二进制向量a，我尝试使用R函数cumsum将其转换为向量b.但是，cumsum并不完全返回向量b.

I have a simple binary vector a which I try to translate into vector b using the R function cumsum. However, cumsum does not exactly return vector b.

这里是一个例子:

a <- c(1,0,0,0,1,1,1,1,0,0,1,0,0,0,1,1)

b <- c(1,2,2,2,3,4,5,6,7,7,8,9,9,9,10,11)

> cumsum(a)
[1] 1 1 1 1 2 3 4 5 5 5 6 6 6 6 7 8

问题在于，只要向量a中出现0，则前一个数字应增加1，但仅对第一个0增加.其余数字将被赋予相同的值.

The problem is that whenever a 0 appears in vector a then the previous number should be increased by 1 but only for the first 0. The remaining ones are given the same value.

任何建议都会很棒！ :-)

Any advise would be great! :-)

推荐答案

诀窍是使用diff标记过渡:

cumsum(as.logical(a+c(0,abs(diff(a)))))
 [1]  1  2  2  2  3  4  5  6  7  7  8  9  9  9 10 11

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