有条件地将因子值从一个数据帧应用到另一个数据帧

# 创建两个数据帧
df1 <- data.frame(ID = c(1, 2, 3), Factor = factor(c("A", "B", "C")))
df2 <- data.frame(ID = c(1, 2, 3), Value = c(10, 20, 30))

# 使用merge()函数将因子值从df1应用到df2
merged_df <- merge(df1, df2, by = "ID")

# 打印合并后的数据帧
print(merged_df)

  ID Factor Value
1  1      A    10
2  2      B    20
3  3      C    30

# 安装和加载dplyr包
install.packages("dplyr")
library(dplyr)

# 创建两个数据帧
df1 <- data.frame(ID = c(1, 2, 3), Factor = factor(c("A", "B", "C")))
df2 <- data.frame(ID = c(1, 2, 3), Value = c(10, 20, 30))

# 使用left_join()函数将因子值从df1应用到df2
merged_df <- left_join(df2, df1, by = "ID")

# 打印合并后的数据帧
print(merged_df)

  ID Value Factor
1  1    10      A
2  2    20      B
3  3    30      C