从向量中提取连续序列 [英] Extract consecutive sequences from vector

问题描述

我有一个名为 v 的向量，其中包含正值和负值以及零.问题是，如何提取(在一个列表中)所有连续的正数序列，即用零分隔的正数序列.

I have a vector called v with positive and negative values as well as zeros. The question is, how to extract (in a list) all the continuous sequences of positive numbers, that is the sequences of positive numbers separated by zeros.

这是 v:

v <- c(-75.09619, -38.31229,   0,  57.17792,  65.55923, 108.52735, 104.29929,  32.47125,0,   0,   0,   0, -26.65008, -49.48638, -79.60670,-90.55343, -34.60761,   0, 21.48842, 38.83820, 42.28727, 0)

输出必须类似于:

[1] 57.17792,  65.55923, 108.52735, 104.29929,  32.47125
[2] 21.48842 , 38.83820, 42.28727

有什么想法吗?

推荐答案

你可以试试:

indices <- which(v[v>=0]==0)
x <- Map(function(x,y) setdiff(v[v>=0][(y+1):(x-1)],0),
         indices[2:length(indices)],
         indices[1:(length(indices)-1)])
x[vapply(x,length,1L)>0]
#[[1]]
#[1]  57.17792  65.55923 108.52735 104.29929  32.47125
#[[2]]
#[1] 21.48842 38.83820 42.28727

我做了什么:

• 从由 v
的 >=0 值形成的向量中取出 0 位置
• 使用Map函数，可以提取两个零之间的向量部分
• 最后一行的目的是从结果中去除没有值的序列(例如，如果原始向量中有两个或多个零的序列)

• took the 0 position out of the vector formed with the >=0 values of v
• with the Map function, you can extract the part of the vector between two zeros
• the last line's purpose is to strip from the result the sequences without values (if for instance there are sequences of two or more zeroes in the original vector)

这篇关于从向量中提取连续序列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！