如何按条件删除R中的前导行和尾随行?

问题描述

存在一个带有前行和后行的数据集，这些行的特征值为零.如何以一种优雅的方式删除这样的行?

There is a data set with leading and trailing rows that have a feature with zero value. How to drop such rows in an elegant way?

# Library
library(tidyverse)

# 1. Input
data.frame(
  id = c(1:10),
  value = c(0, 0, 1, 3, 0, 1, 2, 8, 9, 0))

# 2. Delete leading and trimming rows with 'value = 0'
# ...

# 3. Desired outcome
data.frame(
  id = c(3:9),
  value = c(1, 3, 0, 1, 2, 8, 9))

谢谢.

推荐答案

一个选项是

library(dplyr)
df1 %>%
  filter( cumsum(value) > 0 & rev(cumsum(rev(value)) > 0))
#  id value
#1  3     1
#2  4     3
#3  5     0
#4  6     1
#5  7     2
#6  8     8
#7  9     9

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