R data.table根据字符串值将一行拆分为多行

我有一个data.table，如下所示：

dt <- data.table("title"=c("First Title", "Second Title", "Third Title", "Fourth Title"), 
                 "sha"=c("12345", "2345; 66543; 33423", "22222; 12345678;", "666662345; 444"))

---

提前谢谢

这里有一种使用

tstrsplit

的方法应该适合您：

library(data.table)
dt[, lapply(.SD, function(x) unlist(tstrsplit(x, "; ?"))),
   .SDcols = "sha",by = c("title","date")]
          title     date       sha
1:  First Title 1/1/2020     12345
2: Second Title 1/2/2020      2345
3: Second Title 1/2/2020     66543
4: Second Title 1/2/2020     33423
5:  Third Title 1/3/2020     22222
6:  Third Title 1/3/2020  12345678
7: Fourth Title 1/4/2020 666662345
8: Fourth Title 1/4/2020       444

数据

dt <- data.table("title"=c("First Title", "Second Title", "Third Title", "Fourth Title"), 
                  "sha"=c("12345", "2345; 66543; 33423", "22222; 12345678;", "666662345; 444"),
                  "date" = c("1/1/2020","1/2/2020","1/3/2020","1/4/2020"))

---

dt这是我的
dplyr
解决方案：

dt %>% 
  group_by(title) %>% 
  separate_rows(sha, sep = ";") %>% 
  mutate(sha = as.numeric(sha)) %>% 
  filter(!is.na(sha))

我应该给你这个：

# A tibble: 8 x 2
# Groups:   title [4]
  title              sha
  <chr>            <dbl>
1 First Title      12345
2 Second Title      2345
3 Second Title     66543
4 Second Title     33423
5 Third Title      22222
6 Third Title   12345678
7 Fourth Title 666662345
8 Fourth Title       444

#一个tible:8 x 2
#分组：标题[4]
标题沙
1第一标题12345
2第二标题2345
3第二标题66543
4第二标题33423
5第三标题22222
6第三标题12345678
7第四标题666 2345
8第四标题444
下面是另一个使用
数据的解决方案。表
：

dt[, .(sha = unlist(tstrsplit(sha, ";", type.convert = TRUE))), by = "title"]

#           title       sha
# 1:  First Title     12345
# 2: Second Title      2345
# 3: Second Title     66543
# 4: Second Title     33423
# 5:  Third Title     22222
# 6:  Third Title  12345678
# 7: Fourth Title 666662345
# 8: Fourth Title       444

在这个操作之后，是否可以保留其他列而不仅仅是title和sha？例如，我还有一个日期column@Blind0ne一种更简单的方法：
dt%>%分开的行（sha，sep=“；”）%>%na\u如果（“”）%>%drop\u na（）
@Neel谢谢！实际上，您不需要
drop\u na（）
，但需要对空向量进行过滤<代码>分隔_行（dt，sha）%>%过滤器（sha！=“”）

。

dt[, .(sha = unlist(tstrsplit(sha, ";", type.convert = TRUE))), by = "title"]

#           title       sha
# 1:  First Title     12345
# 2: Second Title      2345
# 3: Second Title     66543
# 4: Second Title     33423
# 5:  Third Title     22222
# 6:  Third Title  12345678
# 7: Fourth Title 666662345
# 8: Fourth Title       444