使用 tidyr 重塑数据

Question

我正在使用一个数据框 data，它的结构与下面的类似。

  Gender   Age         Number
1 Female 55-59 years       5
2 Female   65+ years       10
3   Male 25-29 years       4
4   Male 40-44 years       3
5   Male 50-54 years       1

我正在尝试使用 tidyr 重塑数据（迄今为止未成功），以便 Number 列的每个值都在其自己的行上显示。我正在寻找的输出应该类似于以下内容：

  Gender   Age
1 Female 55-59 years  
2 Female 55-59 years
3 Female 55-59 years
4 Female 55-59 years
5 Female 55-59 years 
6 Female   65+ years
7 Female   65+ years
8 Female   65+ years
9 Female   65+ years
10 Female   65+ years
11 Female   65+ years
12 Female   65+ years
13 Female   65+ years
14 Female   65+ years
15 Female   65+ years
16 Male 25-29 years
17 Male 25-29 years
18 Male 25-29 years
19 Male 25-29 years
20 Male 40-44 years
21 Male 40-44 years
22 Male 40-44 years
23 Male 50-54 years

我尝试使用收集/传播功能的各种组合，但几乎没有成功。我相当确定这在 tidyr 中是可能的！

我知道我可以使用许多其他包/功能来实现相同的结果，但我非常渴望获得一个 tidyr 解决方案，以便我可以将它包含在更大的 dplyr/tidyr 管道中。

非常感谢任何帮助。

dat <- structure(list(Gender = structure(c(3L, 3L, 1L, 2L, 1L), .Label = c("   Male", 
    " Male", "Female"), class = "factor"), Age = structure(c(5L, 
    1L, 2L, 3L, 4L), .Label = c("65+ years", "25-29 years", "40-44 years", 
    "50-54 years", "55-59 years"), class = "factor"), Number = c(5L, 
    10L, 4L, 3L, 1L)), .Names = c("Gender", "Age", "Number"), class = "data.frame", row.names = c(NA, 
    -5L))

Answer 1

这也不是用tidyr，但我觉得很自然：

dat %>% slice(rep(row_number(), Number)) %>% select(-Number)

    Gender         Age
1   Female 55-59 years
2   Female 55-59 years
3   Female 55-59 years
4   Female 55-59 years
5   Female 55-59 years
6   Female   65+ years
7   Female   65+ years
8   Female   65+ years
9   Female   65+ years
10  Female   65+ years
11  Female   65+ years
12  Female   65+ years
13  Female   65+ years
14  Female   65+ years
15  Female   65+ years
16    Male 25-29 years
17    Male 25-29 years
18    Male 25-29 years
19    Male 25-29 years
20    Male 40-44 years
21    Male 40-44 years
22    Male 40-44 years
23    Male 50-54 years

正如@bramtayl 建议的那样，可以（可以说）提高可读性

dat %>% slice(row_number() %>% rep(Number)) %>% select(-Number)

Answer 2

不是 tidyr，但非常快速和高效：

dat2 <- dat[rep(1:nrow(dat), dat[["Number"]]), 1:2]
rownames(dat2) <- NULL

##     Gender          Age
## 1   Female  55-59 years
## 2   Female  55-59 years
## 3   Female  55-59 years
## 4   Female  55-59 years
## 5   Female  55-59 years
## 6   Female    65+ years
## 7   Female    65+ years
## 8   Female    65+ years
## 9   Female    65+ years
## 10  Female    65+ years
## 11  Female    65+ years
## 12  Female    65+ years
## 13  Female    65+ years
## 14  Female    65+ years
## 15  Female    65+ years
## 16    Male  25-29 years
## 17    Male  25-29 years
## 18    Male  25-29 years
## 19    Male  25-29 years
## 20    Male  40-44 years
## 21    Male  40-44 years
## 22    Male  40-44 years
## 23    Male  50-54 years

Answer 3

我们可以使用tidyr/dplyr 做到这一点。将值更改为序列 unnest 后，将“数字”转换为 list 列，并使用 select 从输出中删除“数字”列。

library(dplyr)
library(tidyr)
dat1 <- dat %>% 
          mutate(Number= lapply(Number, seq)) %>%
          unnest(Number) %>% 
          select(-Number)

请注意，输出将是tbl_df，当我们使用dplyr 函数执行其他操作时，这将很有用。

str(dat1)
# Classes ‘tbl_df’, ‘tbl’ and 'data.frame':       23 obs. of  2 variables:
#  $ Gender: Factor w/ 3 levels "   Male"," Male",..: 3 3 3 3 3 3 3 3 3 3 ...
#  $ Age   : Factor w/ 5 levels "65+ years","25-29 years",..: 5 5 5 5 5 1 1 1 1 1 ...

dat1 %>%
     as.data.frame()
#   Gender         Age
#1   Female 55-59 years
#2   Female 55-59 years
#3   Female 55-59 years
#4   Female 55-59 years
#5   Female 55-59 years
#6   Female   65+ years
#7   Female   65+ years
#8   Female   65+ years
#9   Female   65+ years
#10  Female   65+ years
#11  Female   65+ years
#12  Female   65+ years
#13  Female   65+ years
#14  Female   65+ years
#15  Female   65+ years
#16    Male 25-29 years
#17    Male 25-29 years
#18    Male 25-29 years
#19    Male 25-29 years
#20    Male 40-44 years
#21    Male 40-44 years
#22    Male 40-44 years
#23    Male 50-54 years