Question

我有一个数据框，其中“ leg_activity”列的每一行都是一串用逗号分隔的单词：

structure(list(id = c("100", "100060", "100073", "100098", "100102", 
"100104", "100125", "100128", "100149", "100217", "100220", "100271", 
"100464", "100465", "100520", "100607", "100653", "100745", "100757", 
"100760"), leg_activity = c("home", "home, car, work, car, leisure, car, other, car, leisure, car, work, car, shop, car, home", 
"home, walk, leisure, walk, leisure, walk, home", "home, car, other, car, shop, car, other, car, home", 
"home, car, work, car, home, car, home", "home", "home, walk, education, walk, home", 
"home, car, other, car, work, car, shop, car, shop, car, home", 
"home, car, shop, car, work, car, home", "home, bike, leisure, bike, home", 
"home, walk, shop, walk, home", "home, pt, leisure, car, leisure, pt, home", 
"home, car, education, car, home", "home, car, leisure, car, home", 
"home, walk, home, walk, shop, walk, home", "home, pt, work, walk, leisure, walk, work, pt, home", 
"home, pt, leisure, walk, leisure, walk, home", "home, walk, home, bike, shop, bike, home", 
"home, pt, work, pt, home, walk, work, walk, home", "home")), row.names = c(2L, 
15L, 20L, 24L, 31L, 33L, 40L, 43L, 48L, 70L, 73L, 93L, 147L, 
148L, 156L, 174L, 188L, 213L, 214L, 220L), class = "data.frame")

在每个字符串中，我要提取出现在单词work前面的单词。 work可以出现多次，并且每次都需要提取或计算前面的单词。

最终，我想计算一下整个df中work之前哪个单词出现的频率。

我尝试过的事情：

library(dplyr)
library(stringr)

df%>%
  separate_rows(leg_activity, sep = "work, ") %>%
  group_by(id) %>%
  mutate(n = row_number()) %>%
  pivot_wider(names_from = n, values_from = leg_activity)

很显然，这不会导致结果，而只会将df分为几列。因此，也许另一种方法更合适。

非常感谢您的帮助！

Answer 1

您可以将separate_rows与逗号一起使用，以便将单词放在不同的行上。然后，按id分组后，您可以filter行，其中以下/线索行具有“工作”功能吗？

library(dplyr)

df %>%
  separate_rows(leg_activity, sep = ",") %>%
  mutate(leg_activity = trimws(leg_activity)) %>%
  group_by(id) %>%
  filter(lead(leg_activity) == "work") %>%
  summarise(count = n())

输出

# A tibble: 6 x 2
  id     count
  <chr>  <int>
1 100060     2
2 100102     1
3 100128     1
4 100149     1
5 100607     2
6 100757     2

Answer 2

首先，使用稍小的数据集以使其更容易跟踪代码的结果：

d = data.frame(id = 1:3, leg = c("home",
                                 "work, R, eat, work",
                                 "eat, work, R, work"), stringsAsFactors = FALSE)

在strsplit上分割字符串（", "）。循环搜索结果列表（lapply）。获取“工作”的索引（which(x == "work")），获取上一个索引（-1）。如果“ work”是第一个单词，请使用pmax获取空向量。索引单词（x[<the-index>]。取消列出和计数项目（table(unlist(...）。

table(unlist(lapply(strsplit(d$leg, ", "), function(x) x[pmax(0, which(x == "work") - 1)])))
# eat   R 
#   2   1

鉴于“ 最终，我有兴趣计算在整个df上哪个单词出现之前的频率。”，看来分组是不必要的。

Answer 3

library(stringr)
WantedStrings <- sub(", work","",str_extract_all(df$leg_activity, "\\w+, work",simplify=T))
WantedStrings <- WantedStrings[WantedStrings != ""]

table(WantedStrings)


WantedStrings
 car   pt walk 
   5    2    2

Answer 4

R基地一号班轮：

   table(unlist(strsplit(gsub("(\\w+\\,)\\s*(work\\,)", "\\1", 
                           lst$leg_activity), ", ")))

如何提取字符串中某个单词之前的单词？

4 个答案: