如何在R中仅对数据框的指定两列执行pivot_wider操作？

原始数据结构 #

用户的原始长格式分组数据框如下：

df = structure(list(Month = structure(c(946684800, 946684800, 946684800, 
949363200, 949363200, 949363200, 951868800, 951868800, 951868800
), tzone = "UTC", class = c("POSIXct", "POSIXt")), Country = structure(c(1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), levels = c("Italy", "Spain", 
"Portugal", "Ireland", "Germany", "France", "Belgium", "Netherlands", 
"Austria", "Finland"), class = "factor"), bucket = c("long", 
"medium", "short", "long", "medium", "short", "long", "medium", 
"short"), Share_bucket = c(0.403418993584752, 0.445804130974895, 
0.150776875440353, 0.416193617674133, 0.458422829088678, 0.125383553237189, 
0.613769196662502, 0.253456406949091, 0.132774396388407)), class = c("grouped_df", 
"tbl_df", "tbl", "data.frame"), row.names = c(NA, -9L), groups = structure(list(
    Month = structure(c(946684800, 949363200, 951868800), tzone = "UTC", class = c("POSIXct", 
    "POSIXt")), Country = structure(c(1L, 1L, 1L), levels = c("Italy", 
    "Spain", "Portugal", "Ireland", "Germany", "France", "Belgium", 
    "Netherlands", "Austria", "Finland"), class = "factor"), 
    .rows = structure(list(1:3, 4:6, 7:9), ptype = integer(0), class = c("vctrs_list_of", 
    "vctrs_vctr", "list"))), class = c("tbl_df", "tbl", "data.frame"
), row.names = c(NA, -3L), .drop = TRUE))

期望转换为如下宽格式：

Month            Country  short  medium    long    
 
1 2000-01-01 00:00:00 Italy  0.151    0.446   0.403
2 2000-02-01 00:00:00 Italy  0.125    0.458   0.416
3 2000-03-01 00:00:00 Italy  0.133    0.253   0.614

实现代码 #

使用tidyr::pivot_wider结合dplyr工具即可完成转换，先取消数据框的分组状态（避免分组对转换的干扰），再调整列顺序匹配目标格式：

library(tidyr)
library(dplyr)

# 取消分组
df <- ungroup(df)

# 长转宽并调整列顺序
df_wide <- df %>%
  pivot_wider(
    id_cols = c(Month, Country),  # 作为行唯一标识的列
    names_from = bucket,          # 要转为列名的字段
    values_from = Share_bucket    # 对应列的值来源
  ) %>%
  relocate(short, medium, long, .after = Country)  # 调整列的显示顺序

# 查看结果（保留三位小数）
print(df_wide, digits = 3)

关键参数说明 #

• id_cols：指定Month和Country作为唯一行标识，确保每个时间-国家组合只保留一行
• names_from/values_from：完成长格式到宽格式的映射，将bucket的类别转为列名，对应值来自Share_bucket
• relocate：调整列的显示位置，将short/medium/long列移至Country之后，匹配目标格式

内容的提问来源于stack exchange，提问作者Rollo99