提取R中的行序列答案

【问题标题】：Extract sequence of rows in R提取R中的行序列
【发布时间】：2022-07-25 18:09:02
【问题描述】：

我有这种类型的数据：

df <- structure(list(Utterance = c("(5.127)", ">like I don't understand< sorry like how old's your mom¿", 
                                   "(0.855)", "eh six:ty:::-one=", "(0.101)", "(0.487)", "[((v: gasps)) she said] ~no you're [not?]~", 
                                   "[((v: gasps)) she said] ~no you're [not?]~", "~<[NO YOU'RE] NOT (.) you can't go !in!>~", 
                                   "(0.260)", "show her [your boobs] next time"), 
                     Q = c(NA, "q_wh", "", "", NA, NA, "q_really", "", "", NA, NA), 
                     Sequ = c(NA, 1L, 1L, 1L, NA, NA, 0L, 0L, 0L, NA, NA)), class = "data.frame", row.names = c(NA, -11L))

我想提取/过滤

Sequ 的那些行不是 NA 和
前一行（Sequ 是NA）

到目前为止，我的尝试是定义一个获取相关行索引的函数：

QA_sequ <- function(value) {
  inds <- which(!is.na(value) & lag(is.na(value)))  
  sort(unique(c(inds-1, inds)))
}

然后通过索引切出行：

library(dplyr)
df %>% 
  slice(QA_sequ(Sequ))
                                                 Utterance        Q Sequ
1                                                  (5.127)     <NA>   NA
2 >like I don't understand< sorry like how old's your mom¿     q_wh    1
3                                                  (0.487)     <NA>   NA
4               [((v: gasps)) she said] ~no you're [not?]~ q_really    0

但是，只有前一行和第一行 Sequ 会被过滤。 我想要得到的结果是这样的：

                                                  Utterance        Q Sequ
1                                                   (5.127)     <NA>   NA
2  >like I don't understand< sorry like how old's your mom¿     q_wh    1
3                                                   (0.855)             1
4                                         eh six:ty:::-one=             1
5                                                   (0.487)     <NA>   NA
6                [((v: gasps)) she said] ~no you're [not?]~ q_really    0
7                [((v: gasps)) she said] ~no you're [not?]~             0
8                 ~<[NO YOU'RE] NOT (.) you can't go !in!>~             0

编辑：

我想出的解决方案感觉很麻烦：

QA_sequ <- function(value) {
  inds <- which(!is.na(value) & lag(is.na(value)))  
  sort(unique(c(inds-1)))    # extract only preceding row!
}

library(dplyr)
df %>% 
  mutate(id = row_number()) %>%
  slice(QA_sequ(Sequ)) %>%
  bind_rows(., df %>% mutate(id = row_number()) %>% filter(!is.na(Sequ))) %>%
  arrange(id)

【问题讨论】：

标签： r dplyr

【解决方案1】：

这个怎么样？

df %>%
  filter(!is.na(Sequ) | lead(!is.na(Sequ), default=FALSE))
#                                                  Utterance        Q Sequ
# 1                                                  (5.127)     <NA>   NA
# 2 >like I don't understand< sorry like how old's your mom¿     q_wh    1
# 3                                                  (0.855)             1
# 4                                        eh six:ty:::-one=             1
# 5                                                  (0.487)     <NA>   NA
# 6               [((v: gasps)) she said] ~no you're [not?]~ q_really    0
# 7               [((v: gasps)) she said] ~no you're [not?]~             0
# 8                ~<[NO YOU'RE] NOT (.) you can't go !in!>~             0

逻辑过滤器（提取）两者：

所有非NA 值
任何NA 值，其中下一个值不是NA

【讨论】：

这很好。比 OP 的方法或我的变体要简单得多。
default = FALSE 到底是做什么的？
@ChrisRuehlemann，将lead(c(T,F,T)) 与lead(c(T,F,T), default=F)（或default=T) 进行比较。与lag(c(T,F,T)) 和lag(c(T,F,T), default=F) 进行比较。

【解决方案2】：

只需添加一个额外的 OR 即可收集 sequ 不是 NA 但没有相应滞后非NA 的行...

QA_sequ <- function(value) {
  inds <- which((!is.na(value) & lag(is.na(value))) | !is.na(value))  
  sort(unique(c(inds-1, inds)))
}

df %>%  slice(QA_sequ(Sequ))
                                                 Utterance        Q Sequ
1                                                  (5.127)     <NA>   NA
2 >like I don't understand< sorry like how old's your mom¿     q_wh    1
3                                                  (0.855)             1
4                                        eh six:ty:::-one=             1
5                                                  (0.487)     <NA>   NA
6               [((v: gasps)) she said] ~no you're [not?]~ q_really    0
7               [((v: gasps)) she said] ~no you're [not?]~             0
8                ~<[NO YOU'RE] NOT (.) you can't go !in!>~             0

【讨论】：

【解决方案3】：

这是使用基数 R。就像您在前面的行中获取行的索引一样。

x<-which(!is.na((df$Sequ))) 
x1 <- x-1
x<- unique(c(x,x1))
x<- x[order(x)]    


df[x,]

您可以将相同的向量传递给slice 到df %>% slice(x)

【讨论】：