Shiny App R - Reactive variables not responding to change in Input variables - r

Question

I'm making an app that will predict an NFL running back's number of rush attempts and rush yards AFTER a season of 1800+ rush yards. I use slider inputs for the # of rushing yards and attempts, which gets run through lm() and predict() and returns estimates for next year's attempts and rush yards (I know it's not a very good predictor at all, but this is just an exercise in making a Shiny app). Here's the data from my excel file and then the code.
Player Yr. Team Attempts Att.Next.Yr Yards Yards.Next.Yr YPC YPC.Next.Yr
1 Adrian Peterson 2012 MIN 348 279 2097 1266 6.0 4.5
2 Chris Johnson 2009 TEN 358 316 2006 1364 5.6 4.3
3 LaDainian Tomlinson 2006 SD 348 315 1815 1474 5.2 4.7
4 Shaun Alexander 2005 SEA 370 252 1880 896 5.1 3.6
5 Tiki Barber 2005 NYG 357 327 1860 1662 5.2 5.1
6 Jamal Lewis 2003 BAL 387 235 2066 1006 5.3 4.3
7 Ahman Green 2003 GB 355 259 1883 1163 5.3 4.5
8 Ricky Williams 2002 MIA 383 392 1853 1372 4.8 3.5
9 Terrell Davis 1998 DEN 392 67 2008 211 5.1 3.1
10 Jamal Anderson 1998 ATL 410 19 1846 59 4.5 3.1
11 Barry Sanders 1997 DET 335 343 2053 1491 6.1 4.3
12 Barry Sanders 1994 DET 331 314 1883 1500 5.7 4.8
13 Eric Dickerson 1986 RAM 404 60 1821 277 4.5 4.6
14 Eric Dickerson 1984 RAM 379 292 2105 1234 5.6 4.2
15 Eric Dickerson 1983 RAM 390 379 1808 2105 4.6 5.6
16 Earl Campbell 1980 HOU 373 361 1934 1376 5.2 3.8
17 Walter Payton 1977 CHI 339 333 1852 1395 5.5 4.2
18 O.J. Simpson 1975 BUF 329 290 1817 1503 5.5 5.2
19 O.J. Simpson 1973 BUF 332 270 2003 1125 6.0 4.2
20 Jim Brown 1963 CLE 291 280 1863 1446 6.4 5.2
Server.R
# server.R
library(UsingR)
library(xlsx)
rawdata <- read.xlsx("RushingYards.xlsx", sheetIndex=1)
data <- rawdata[c(2:21),]
rownames(data) <- NULL
# Att
set.seed(1)
fitAtt <- lm(Att.Next.Yr ~ Yards + Attempts, data)
# Yds
set.seed(1)
fitYds <- lm(Yards.Next.Yr ~ Yards + Attempts, data)
shinyServer(
function(input, output) {
output$newPlot <- renderPlot({
iYards <- input$Yards
iAttempts <- input$Attempts
test <- data.frame(iYards,iAttempts)
names(test) <- c("Yards", "Attempts")
predictAtt <- predict(fitAtt, test)
predictYds <- predict(fitYds, test)
qplot(data=data, x=Attempts, y=Yards) +
geom_point(aes(x=predictAtt, y=predictYds, color="Estimate"))
output$renderYds <- renderPrint({predictYds})
output$renderAtt <- renderPrint({predictAtt})
})
}
)
UI.R
# ui.R
shinyUI(pageWithSidebar(
headerPanel("Rushing Projections"),
sidebarPanel(
sliderInput('Yards', 'How many yards rushed for this season',
value=1700, min=1500, max=2500, step=25,),
sliderInput('Attempts', 'How many attempts this season',
value=350, min=250, max=450, step=5,),
submitButton('Submit')
),
mainPanel(
plotOutput('newPlot'),
h3('Predicted rushing yards next year: '),
verbatimTextOutput("renderYds"),
h3('Predict attempts next year: '),
verbatimTextOutput("renderAtt")
)
))
The problem I'm having is I can't seem to output BOTH the plot (next year's estimates plotted in red against historical performances for running backs > 1800 rush yards) and the text of next year's estimated rushing yards and attempts at the same time. I can get one or the other to show up depending on where I put those statements. If I put
output$renderYds <- renderPrint({predictYds})
output$renderAtt <- renderPrint({predictAtt})
outside of the output$newPlot (but still inside of function(input, output)) line I can get the plot to show up and the point for next year's estimates changes as the input is changed but I get error messages of
object 'predictYds' not found' and object 'predictAtt' not found for the text. If I put those two lines inside of the function(input, output) line (as I have in the code above) then those two text numbers show up with the correct value but the plot doesn't generate.
Can anyone help with this please?

Answer 1

I changed the structure of Server.R and now it works.
shinyServer(function(input, output) {
predictYds <- function(Y, A){
test <- data.frame(Y, A)
names(test) <- c("Yards", "Attempts")
predict(fitYds, test)
}
predictAtt <- function(Y, A){
test <- data.frame(Y, A)
names(test) <- c("Yards", "Attempts")
predict(fitAtt, test)
}
output$newPlot <- renderPlot({
newYards <- predictYds(input$Yards, input$Attempts)
newAttempts <- predictAtt(input$Yards, input$Attempts)
qplot(data=data, x=Attempts, y=Yards) +
geom_point(aes(x=newAttempts, y=newYards, color="Estimate"))
})
output$renderYds <- renderPrint({predictYds(input$Yards, input$Attempts)})
output$renderAtt <- renderPrint({predictAtt(input$Yards, input$Attempts)})
}
)
Basically PredictYds and PredictAtt were rewritten as normal functions called inside render functions using input variables.