如何在R中的if循环中将数据帧拆分为特定的行数

Question

I am writing a function to send emails to my clients in R. I am using mailR package to do so,but my service provider only allows me to send 100 emails an hour. What I want to do is, if suppose my email list contains 270 email addresses,I want to spilt that into chunk1=100 , chunk2 = 100 & chunk3 = 70 Then it should send out emails to first chunk then wait for an hour and then chunk2 and so on. This is my function looks like.

email <- function(dataframe,city,date){
   dataframe$registrant_email <- tolower(dataframe$registrant_email)
   dataframe_city <- dataframe[dataframe$registrant_city == city & dataframe$create_date == date, ]
   # Removing NA's and blank email ids
   dataframe_city <- dataframe_city[!(is.na(dataframe_city$registrant_email)|dataframe_city$registrant_email==""), ]
   # Removing duplicate email ids
   dataframe_city <-dataframe_city[!duplicated(dataframe_city$registrant_email),]
   emails <- as.vector(dataframe_city$registrant_email)
   if(length(emails) > 100){

   # divide the vector into chunks of 100


   } else{send_email(emails}

  return(emails) 
}

I need a help in if loop how can I write the splitting part into chunk of 100 and then call a send_email function wait for an hour and so on.

Answer 1

You can split your email-vector into a list with a one-liner:

mailinglist <- split(emails, ceiling(seq_along(emails)/100))

Then you could delay the execution of the mailing by something like:

for(i in mailinglist) {
 send_email(i)
 Sys.sleep(3600)}

I tested the loop with a simple mean() call and it worked, but you should test it yourself with a lower time and by sending mails to yourself.

Edit: To omit the delay on the last iteration, use this:

for(i in 1:length(mailinglist)) {
 if(i < length(mailinglist)) {
  send_email(mailinglist[[i]])
  Sys.sleep(3600)}
 else {
  send_email(mailinglist[[i]])}
}