[R] is there any method to defer the execution of code in r?

[Rui Barradas]

Hello,

This is cross posted from StackOverflow:

https://stackoverflow.com/questions/50314015/is-there-any-method-to-defer-the-execution-of-code-in-r

Cross posting is discouraged in r-help.

Rui Barradas

On 5/13/2018 8:59 AM, akshay kulkarni wrote:
> dear members,
> 
> I have created the following function to read a csv file from a given URL:
> 
>      function(){
>                              s <- 1;
> 
>                              #first get the bhav copy
>                              today <- c();ty <- c();tm <- c();tmu <- c();td <- c();
> 
>                             # get the URL first
>                              today <- Sys.Date()
>                              ty <- format(today, format = "%Y")
>                              tm <- format(today, format = "%b")
>                              tmu <- toupper(tm)
>                              td <- format(today, format = "%d")
> 
>             dynamic.URL <- paste("https://www.nseindia.com/content/historical/EQUITIES/",ty,"/",tmu,"/cm",td,tmu,ty,"bhav.csv.zip", sep = "")
>             file.string <- paste("C:/Users/user/AppData/Local/Temp/cm",td,tmu,ty,"bhav.csv")
> 
>                              download.file(dynamic.URL, "C:/Users/user/Desktop/bhav.csv.zip")
>                              bhav.copy <- read.csv(file.string)
>                              return(bhav.copy)
>      }
> 
> If I run the function, immediately it says that "file.string not found". But when I run it after some time(a few seconds), it executes normally. I think when `download.file` ecexecutes, it transfers control to `read.csv, `and it tries to load the file which is not yet properly saved. when I run it after some time, it tries to overwrite the existing file, which it cannot, and the `read.csv`properly loads the saved file.`
> 
> I want the function to execute the first time I run it. Is there any way or a function to defer the action of `read.csv`until the file is properly saved? Something like this:
> 
>      download.file(dynamic.URL, "C:/Users/user/Desktop/bhav.csv.zip")
>                                  wait......
>                                  bhav.copy <- read.csv(file.string)
> 
> Ignore the fact that the destfile in download.file is different from file.string; it is due to function of my system (windows 7).
> 
> Very many thanks for your time and effort...
> 
> AKSHAY  M KULKARNI
> 
> 
> 	[[alternative HTML version deleted]]
> 
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