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

[akshay kulkarni]

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


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