R: Running computation while waiting for user input - r

Question

do you see a way to run a computation in R while waiting for a user input?
I'm writing a script that makes differents types of plots which are defined by user input, but in first lot of data has to be loaded and processed. But in fact, user could start defining what he wants already while the processing is running - that's what I would like to do!
I think package Rdsn might provide the functionality that I need, but I was not able to figure out how.
Thanks!

Answer 1

You didn't give me much context, nor reproducible code, so I will just provide a simple example. I am not familiar with the Rdsn package, so I will use provide a solution I know.
# create a function to prompt the user for some input
readstuff = function(){
stuff = readline(prompt = "Enter some stuff: ")
# Here is where you set the condition for the parameter
# Let's say you want it to be an integer
stuff = as.integer(stuff)
if(is.na(stuff)){
return(readstuff())
} else {
return(stuff)
}
}
parameter = readstuff()
print(parameter)
print(parameter + 10)
The key here is to "source" the script instead of "running" it. You can find the "source" button on the top right of RStudio. You can also use source(yourscript) to source it.
So for every parameter you want to prompt the user for input, just call readstuff(). You can also tweak it a little to make it more general. For example:
# create a function to prompt the user for some input
readstuff = function(promptMessage = "stuff", class = "integer"){
stuff = readline(prompt = paste("Enter the", promptMessage, ": "))
# Here is where you set the condition for the parameter
# Let's say you want it to be an integer
stuff = as(stuff, class)
if(is.na(stuff)){
return(readstuff(promptMessage, class))
} else {
return(stuff)
}
}
plotColor = readstuff("plot color", "character")
size = readstuff("size parameter")
xvarName = readstuff("x axis name", "character")
df = data.frame(x = 1:100, y = 1:100)
library(ggplot2)
p = ggplot(df, aes(x = x, y = y, size = size, color = plotColor)) +
labs(x = xvarName) + geom_point()
print(p)
The if(is.na(stuff)) statements won't work if class is character, but I won't get into details on how to fix that, since this question is mainly about how to wait for user input. There are also ways to suppress the warning messages if the user entered something other than what is intended, but again, a bit off topic to talk about it here.
One important thing you have to watch out for is that anything you want R to print or plot, you need to wrap it with a print() function. Otherwise sourcing it won't print nor plot anything. Also, when typing in a parameter that is intended to be a string or character, don't add quotes. For example, for plotColor, type red instead of "red" in the prompt.
Most of the readline code are referenced from here: