我需要从R中的df采样n组n个随机行

Question

I want to iterate n times a function that draws n rows at random from a dataframe. Since the groups consist each of 785 rows, the function is this:

randomSample = function(merged_df_1, n) { 
  return( merged_df_1[sample(nrow(merged_df_1), 785),] )
}

To iterate this function 10 times, I tried this code

n=10
lapply(rep(1, n), randomSample)

But I get the following error message

"Error in sample.int(length(x), size, replace, prob) : invalid first argument"

Answer 1

What's happening is that lapply takes the rep(1,n) vector and uses it as the first argument of your function. I guess you could do this:

randomSample = function(n, merged_df_1) { 
#note that the function doesn't really use n inside it, if you want so, you should #replace 785 for n and use rep(n,n) inside the lapply call
  return(merged_df_1[sample(nrow(merged_df_1), 785),] )
}

n=10
lapply(rep(1,n), function(x)randomSample(x,merged_df_1))