r - 通过随机化数据框生成多个文件

Question

我需要从数据框的随机化中生成并保存多个文件。 原始数据框是几年的每日天气数据。我需要生成随机重组年份但保持年份顺序的文件。

我开发了一个用于随机化年份的简单代码，但我无法重复随机化并将每个输出随机数据帧保存为单独的文件。

这是我目前所拥有的：

# Create example data frame
df <- data.frame(x=c(1,1,1,2,2,2,3,3,3,4,4,4,5,5,5,6,6,6,7,7,8,8))
df$y <- c(4,8,9,1,1,5,8,8,3,2,0,9,4,4,7,3,5,5,2,4,6,6)
df$z <- c("A","A","A","B","B","B","C","C","C","D","D","D","F","F","F","G","G","G","H","H","I","I")

set.seed(30)

# Split data frame based on info in one column (i.e. df$x) and store in a list 
dt_list <- split(df, f = df$x)

# RANDOMIZE data list -- Create a new index and change the order of dt_list
# SAVE the result to "random list" (i.e. 'rd_list')

rd_list <- dt_list[sample(1:length(dt_list), length(dt_list))]

# Put back together data in the order established in 'rd_list' 
rd_data <- do.call(rbind, rd_list)

这就像我需要的那样随机化数据框，但我不知道如何“保存并重复”所以我得到多个文件，比如说大约 20 个，命名为原始和顺序编号（例如 df_1、df_2 ...)。

此外，作为随机样本，有可能得到重复。有没有办法自动丢弃重复的文件？

谢谢！

Answer 1

这是一种利用while 循环和dplyr 包中方便的sample_n() 函数的方法，它从数据框中采样指定数量的行（有或没有替换）。

library(dplyr)

# Create the data
weather_data <- data.frame(Weather = c("Sunny", "Cloudy", "Rainy", "Sunny"),
                           Temperature = c(75, 68, 71, 76))

# Twenty times, repeatedly sample rows from the data and write to a csv file
total_files <- 20
df_index <- 1

while (df_index <= total_files) {
  # Get a sample of the data
  sampled_subset <- sample_n(weather_data,
                             size = 10,
                             replace = TRUE)

  # Write the data to a csv file
  filename_to_use <- paste0("Sample_Data", "_", df_index, ".csv")

  write.csv(x = sampled_subset,
            file = filename_to_use, sep = ",")

  df_index <- df_index + 1
}