r-将所有单元格长度为1的列表列简化为向量列

Question

我有一个tibble，其中包括一些列表列。

library(dplyr)
df <- structure(
list(ID = 1:5, V1 = list(1.71, -0.59, 0.73, -0.93, 0.18),
V2 = list(-0.08, c(0.59, 0.87), -1.87, -1.38, 0.83), 
V3 = list(-0.25, -0.02, -0.97, -1.62, 0.54),
V4 = list(-0.12, 0.73, -0.36, 0.55, c(0.92, -0.49)),
V5 = list(c(-0.11, 0.14), -0.2, c(-1.12, -0.91), 0.14, c(1.56, 0.33))),
row.names = c(NA, -5L), class = c("tbl_df", "tbl", "data.frame"))
# # A tibble: 5 × 6
#      ID V1        V2        V3        V4        V5       
#   <int> <list>    <list>    <list>    <list>    <list>   
# 1     1 <dbl [1]> <dbl [1]> <dbl [1]> <dbl [1]> <dbl [2]>
# 2     2 <dbl [1]> <dbl [2]> <dbl [1]> <dbl [1]> <dbl [1]>
# 3     3 <dbl [1]> <dbl [1]> <dbl [1]> <dbl [1]> <dbl [2]>
# 4     4 <dbl [1]> <dbl [1]> <dbl [1]> <dbl [1]> <dbl [1]>
# 5     5 <dbl [1]> <dbl [1]> <dbl [1]> <dbl [2]> <dbl [2]>

我想将所有单元格长度为1的列表列(即V1和V3)简化为向量列。如果有任何单元格的编号大于1，则保持该列不变。预期输出如下:

# A tibble: 5 × 6
ID    V1 V2           V3 V4        V5       
<int> <dbl> <list>    <dbl> <list>    <list>   
1     1  1.71 <dbl [1]> -0.25 <dbl [1]> <dbl [2]>
2     2 -0.59 <dbl [2]> -0.02 <dbl [1]> <dbl [1]>
3     3  0.73 <dbl [1]> -0.97 <dbl [1]> <dbl [2]>
4     4 -0.93 <dbl [1]> -1.62 <dbl [1]> <dbl [1]>
5     5  0.18 <dbl [1]>  0.54 <dbl [2]> <dbl [2]>

我已经用冗长的lapply()和if语句实现了它。我期待tidyverse解决方案或简洁的base解决方案。谢谢你的帮助。

Answer 1

您可以在across()中使用where()来确定哪些列表列的长度都为1。

library(dplyr)
df %>%
mutate(across(where(~ all(lengths(.x) == 1)), unlist))
# # A tibble: 5 × 6
#      ID    V1 V2           V3 V4        V5       
#   <int> <dbl> <list>    <dbl> <list>    <list>   
# 1     1  1.71 <dbl [1]> -0.25 <dbl [1]> <dbl [2]>
# 2     2 -0.59 <dbl [2]> -0.02 <dbl [1]> <dbl [1]>
# 3     3  0.73 <dbl [1]> -0.97 <dbl [1]> <dbl [2]>
# 4     4 -0.93 <dbl [1]> -1.62 <dbl [1]> <dbl [1]>
# 5     5  0.18 <dbl [1]>  0.54 <dbl [2]> <dbl [2]>

Answer 2

基数R的解可以是，

i1 <- sapply(df, (i)all(lengths(i) == 1))
df[i1] <- lapply(df[i1], unlist)
df
# A tibble: 5 × 6
ID    V1 V2           V3 V4        V5       
<int> <dbl> <list>    <dbl> <list>    <list>   
1     1  1.71 <dbl [1]> -0.25 <dbl [1]> <dbl [2]>
2     2 -0.59 <dbl [2]> -0.02 <dbl [1]> <dbl [1]>
3     3  0.73 <dbl [1]> -0.97 <dbl [1]> <dbl [2]>
4     4 -0.93 <dbl [1]> -1.62 <dbl [1]> <dbl [1]>
5     5  0.18 <dbl [1]>  0.54 <dbl [2]> <dbl [2]>