如何获取data.frames列表中特定data.frame的索引？

get_dataframe_index <- function(dataframes, target_df) {
  for (i in seq_along(dataframes)) {
    if (identical(dataframes[[i]], target_df)) {
      return(i)
    }
  }
  return(NULL)
}

get_dataframe_index <- function(dataframes, target_df) {
  index <- which(lapply(dataframes, identical, target_df))
  if (length(index) > 0) {
    return(index)
  } else {
    return(NULL)
  }
}

# 创建data.frames列表
df1 <- data.frame(a = 1:3, b = letters[1:3])
df2 <- data.frame(x = 4:6, y = letters[4:6])
df3 <- data.frame(m = 7:9, n = letters[7:9])
dataframes <- list(df1, df2, df3)

# 获取特定data.frame的索引
target_df <- data.frame(x = 4:6, y = letters[4:6])
index <- get_dataframe_index(dataframes, target_df)
print(index)

[1] 2