CODEWITHSUNDEEP
rrandom
ebb
ebb

Reputation: 274

r - generate multiple files from randomizing a data frame

I need to generate and save multiple files from the randomization of a data frame. The original data frames are daily weather data for several years. I need to generate files that are random reorganizations of the years but keeping the year sequence.

I have developed a simple code for randomizing years, but I am having trouble to repeat randomization and save each output randomized data frame as a separate file.

This is what I have thus far:

# 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)

This randomizes the data frame just as I need, but I don't know how to "save & repeat" so I get multiple files, let's say about 20, named as the original and a sequential numeration (e.g. df_1, df_2 ...).

Also, being random samples, it's possible to get repetitions. Is there any way to automatically discard repeated files?

Thanks!

Upvotes: 0

Views: 261

Answers (1)

bschneidr
bschneidr

Reputation: 6277

Here's an approach that makes use of a while loop and the handy sample_n() function from the dplyr package, which samples a specified number of rows from a data frame (with or without replacement).

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
}

Upvotes: 2

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