在R语言中转置数据框单列到行并保留结构的实现方法

你需要将原数据框按ID和class作为行标识，把code的不同取值转为列，对应填充n的数值，空值留空。以下是两种可行的实现方法：

方法一：使用tidyverse工具包（推荐） #

先加载dplyr和tidyr，通过pivot_wider完成数据重塑，再处理空值：

# 加载所需工具包
library(dplyr)
library(tidyr)

# 原始数据框
df <- data.frame(ID = c("A","A","A","A","A","B","B","B","B","B","C","C","C","C","C"),
                 code = c(1,2,2,3,3,1,2,2,1,1,3,2,2,1,1),
                 class =  c(2,4,5,5,2,3,2,5,1,2,4,5,3,2,1),
                 n = c(10,10,20,15,25,20,10,10,20,25,10,15,10,15,15))

# 执行数据重塑
result_tidy <- df %>%
  pivot_wider(
    id_cols = c(ID, class),  # 指定行标识列
    names_from = code,       # 将该列的取值转为新列名
    values_from = n,         # 填充新列的数值来源
    names_prefix = ""        # 新列名无需前缀
  ) %>%
  mutate(across(-c(ID, class), ~replace_na(.x, "")))  # 将空值替换为空白字符串

# 查看结果
print(result_tidy, na.print = "")

输出结果示例（与你预期格式匹配）：

方法二：使用Base R的reshape函数 #

若不想加载额外工具包，可直接用Base R内置的reshape函数实现：

# 原始数据框
df <- data.frame(ID = c("A","A","A","A","A","B","B","B","B","B","C","C","C","C","C"),
                 code = c(1,2,2,3,3,1,2,2,1,1,3,2,2,1,1),
                 class =  c(2,4,5,5,2,3,2,5,1,2,4,5,3,2,1),
                 n = c(10,10,20,15,25,20,10,10,20,25,10,15,10,15,15))

# 执行数据重塑
result_base <- reshape(df, 
                       idvar = c("ID", "class"), 
                       timevar = "code", 
                       direction = "wide",
                       v.names = "n")

# 重命名列，去掉默认的"n."前缀
colnames(result_base) <- gsub("n\\.", "", colnames(result_base))

# 将空值替换为空白字符串
result_base[is.na(result_base)] <- ""

# 查看结果
print(result_base)

该方法同样能得到与预期一致的结果。

内容的提问来源于stack exchange，提问作者starski