R Shiny, working with reactive dataframes - NAs - r

Question

I'm trying to populate a data.frame/matrix based on some user-defined rules. I managed to create a function in R, but am stuck trying to replicate this as a Shiny app [it's my first time using Shiny, and I'm an idiot to start with this one]
This is the crux of the code in regular r-script -
user-inputs are: size (1~3), changes (1~2) and iterations (10~1000)
school_choice_function<- function(changes, size, iterations )
{
######## 1509
##### List of schools
p<-1
j<-1
k<-1
l<-1
s_list<- rep(0,80)
for (i in 1:80) {
if (i <= 26) {
schl<- paste(LETTERS[p],LETTERS[i],sep = "")
s_list[i]<- schl }
if (i>26 & i<=52) {p<- 2
schl<- paste(LETTERS[p],LETTERS[j],sep = "")
s_list[i]<- schl
j=j+1}
if (i>52 & i<=78) {p<- 3
schl<- paste(LETTERS[p],LETTERS[k],sep = "")
s_list[i]<- schl
k=k+1}
if (i>78 ) {p<- 4
schl<- paste(LETTERS[p],LETTERS[l],sep = "")
s_list[i]<- schl
l=l+1}
}
rm(p,i,j,k,l)
########## Applicant Data
a<- c(2011:2015)
c<- 1:size
d<- 1:changes
y<-0
v<-1
w<-10
mat <- matrix(ncol=5, nrow=(iterations*10))
for(pop in 1:iterations){
for (z in v:w)
{
b<- s_list[(1+y):(8+y)]
e<- rep(0,5)
e[1]<- b[1]
g<- sample(d,1)
h<- sample(2:5,g, replace = FALSE)
f1<- rep(0,length(h))
for(j in 1:g){
for(i in 1:length(h))
{
f<- sample(c, 1)
f1[i]<- paste(sample(b,f,replace = FALSE),collapse = ",")
e[h[i]]<- f1[i]
}
}
for(i in c(which(e %in% 0))){
e[i]<- e[i-1]
}
mat[z,]<- e
y<-y+8
}
v<- w+1
w<- w+10
y<-0
}
df<- data.frame(mat,stringsAsFactors = FALSE)
colnames(df)<- c("2011","2012","2013","2014","2015")
return(df)
}
Ignoring the use of worst-practices in coding (I've just learnt to think in terms of loops), I'm using this is a shiny app like this. "s_list/schools" is a character matrix with 80 elements, created before this code.
Just so you get an intuition of what on earth is this - basically it is applicant data over 5 years, who may or many not get assigned to alternatives over time, (based on the rules which comes through in the loops).
The code works in the current form - except the output table is full of NAs.... Any kind of help would be a step up from where I'm at!
ui<- fluidPage(
numericInput(inputId="Changes", label="Changes", value=1, min = 1, max = 3, step = 1),
numericInput(inputId="Size", label="Size", value=2, min = 1, max = 3, step = 1),
numericInput(inputId="Iterations", label="Iterations", value=10, min = 10, max = 1000, step = 10),
tableOutput("dframe")
)
server<- function(input,output) {
Changes<- reactive({input$Changes})
Size<- reactive({input$Size})
Iterations<- reactive({input$Iterations})
schools<- s_list
########## Applicant Data
a<- c(2011:2015)
cc<- reactive(1:(Size()))
d<- reactive(1:(Changes()))
y<-0
v<-1
w<-10
mat <- reactive(matrix(ncol=5, nrow=((input$Iterations)*10)))
pop<- 0
z<- 0
i<- 0
j<- 0
this<- reactive({
for(pop in 1:(Iterations())){
for (z in v:w)
{
b<- schools[(1+y):(8+y)]
e<- rep(0,5)
e[1]<- b[1]
g<- reactive(sample(d(),1))
h<- reactive(sample(2:5,g(), replace = FALSE))
f1<- reactive(rep(0,length(h())))
for(j in 1:g()){
for(i in 1:length(h()))
{
f<- reactive(sample(cc(), 1))
f1()[i]<- reactive(paste(sample(b,f(),replace = FALSE),collapse = ","))
e[h()[i]]<- f1()[i]
}
}
for(i in cc()(which(e %in% 0))){
e[i]<- e[i-1]
}
mat()[z,]<- e
y<-y+8
}
v<- w+1
w<- w+10
y<-0
}
})
df<- reactive(data.frame(mat(),stringsAsFactors = FALSE))
output$dframe <- renderTable({ df() })
}
shinyApp(ui= ui, server = server)

Answer 1

Instead of writing the whole code of the function school_choice_function inside your server why don't you define the function outside your server and just call it from inside your server. Something like this:
server<- function(input,output) {
Changes<- reactive({input$Changes})
Size<- reactive({input$Size})
Iterations<- reactive({input$Iterations})
df<- reactive({
df <- school_choice_function(Changes(), Size(), Iterations())
return(data.frame(df, stringsAsFactors = FALSE))
})
output$dframe <- renderTable({ df() })
}