使用R在不同长度的列之间映射和赋值

# 创建两个数据框
df1 <- data.frame(id = 1:3, value1 = c("A", "B", "C"))
df2 <- data.frame(id = 1:2, value2 = c("X", "Y"))

# 合并数据框
merged_df <- merge(df1, df2, by = "id", all.x = TRUE)
print(merged_df)

library(dplyr)

# 创建两个数据框
df1 <- data.frame(id = 1:3, value1 = c("A", "B", "C"))
df2 <- data.frame(id = 1:2, value2 = c("X", "Y"))

# 左连接
left_joined_df <- left_join(df1, df2, by = "id")
print(left_joined_df)

# 右连接
right_joined_df <- right_join(df1, df2, by = "id")
print(right_joined_df)

# 创建两个向量
vec1 <- c("A", "B", "C")
vec2 <- c("B", "C")

# 匹配位置
match_positions <- match(vec2, vec1)
print(match_positions)

# 检查包含关系
contains <- vec1 %in% vec2
print(contains)

# 去除重复行
merged_df <- distinct(merged_df)
print(merged_df)

# 检查匹配结果
if (is.na(match_positions)) {
  print("匹配失败")
} else {
  print("匹配成功")
}