在布尔向量中找到最长的TRUE连续块 [英] Find the longest continuous chunk of TRUE in a boolean vector

问题描述

给出一个布尔向量，如何找到最长的连续块TRUE并将其余的TRUE值更改为FALSE?

Given a boolean vector, how can I find the longest continuous chunk of TRUE and change the rest TRUE values to FALSE?

例如，给定布尔向量:

bool = c(TRUE, TRUE, FALSE, TRUE, TRUE, TRUE, TRUE, FALSE)

我如何获得像这样的向量:

How can I get a vector like:

c(FALSE, FALSE, FALSE, TRUE, TRUE, TRUE, TRUE, FALSE)

推荐答案

这是一种在布尔向量中突出显示连续TRUE的所有最长块的方法.这意味着，例如，如果有两个长度相同(最大)的TRUE块，则在输出中都将报告为TRUE.

Here's an approach that will highlight all longest chunks of consecutive TRUEs in a boolean vector. That means, if there are, say, two TRUE chunks of the same (max) length, both will be reported as TRUE in the output.

我们可以使用:

with(rle(bool), rep(lengths == max(lengths[values]) & values, lengths))

这意味着:

• with(rle(bool), ...):计算行程长度
• lengths == max(lengths[values]) & values:检查每个游程长度是否等于值TRUE 的最大游程长度，还检查值本身是否为TRUE
• rep(...., lengths):按照自己的游程长度重复每个结果逻辑

• with(rle(bool), ...): compute the run lengths
• lengths == max(lengths[values]) & values: check if each run length is equal to the maximum run length where values is TRUE and also check if values itself is TRUE
• rep(...., lengths): repeat each of the resulting logicals as often as it's own run length

OP的测试用例:

bool <- c(TRUE, TRUE, FALSE, TRUE, TRUE, TRUE, TRUE, FALSE)
with(rle(bool), rep(lengths == max(lengths[values]) & values, lengths))
# [1] FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE FALSE

第二个测试用例:T和F的最大值相同:

Second test case: same maxima for T and F:

x <- c(TRUE, TRUE, FALSE, FALSE, TRUE, FALSE, FALSE, TRUE, FALSE, TRUE)
with(rle(x), rep(lengths == max(lengths[values]) & values, lengths))
# [1]  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE

第三个测试用例:F比T更长的块:

Third test case: F longer chunk than T:

y <- c(TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE, TRUE, FALSE, TRUE)
with(rle(y), rep(lengths == max(lengths[values]) & values, lengths))
# [1]  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE

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