R Shiny dynamically edit reactiveTimer timer interval - r

Question

I am trying to create an R shiny dashboard which has a play and pause button for updating displaying a graph data along a sequence of time. To do this I was using a reactiveTimer, but it does not allow me to dynamically edit the reactiveTimer interval.
Error in .getReactiveEnvironment()$currentContext() :
Operation not allowed without an active reactive context. (You tried to do something that can only be done from inside a reactive expression or observer.)
My attempted code is
library(shiny)
library(ggplot2)
library(tidyr)
input.df <- read.csv(file = 'InputData.csv', header = TRUE, sep=",")
ui<-fluidPage(
titlePanel("Auckland Volcanic Simulation"),
hr(style="border-color: grey;"),
sidebarLayout(
# panel with all inputs
sidebarPanel(
fluidRow(
column(7,actionButton("stop","Pause")),
column(5,actionButton("play","Play"))
),
fluidRow(
column(7,actionButton("skip","Skip")),
column(3,actionButton("reset","Reset"))
)
),
# plot panel
mainPanel(
# visual data on same row
fluidRow(
span(textOutput("Date"), style="font-size: 24px;font-style: italic;")
),
fluidRow(
column(12,plotOutput('defGraph'))
)
)
)
)
server<-function(input,output){
control<-reactiveValues() # reactive to store all reactive variables
control$resetindicator<-0 # used to change button labels
control$count<-0 # day number in sequence
control$min<-0
control$max<-0
control$timer<-Inf
forward<-function(){
print("in forward")
control$resetindicator<-1 # change button label
step <- 12
if (step >= control$count) {
min <- 0
max <- control$count
} else {
min <- control$count - step
max <- control$count
}
control$min <- min
control$max <- max
control$count<-control$count+1
}
observeEvent(input$skip,{
forward()
})
session<-reactiveValues()
session$timer<-reactiveTimer(intervalMs = control$timer, session = getDefaultReactiveDomain())
observeEvent(input$play,{
print("play")
control$timer<-1000
#session$timer<-reactiveTimer(intervalMs = 1000, session = getDefaultReactiveDomain())# Time interval
observeEvent(session$timer(),{
print("calling forward")
forward()
})
})
observeEvent(input$stop,{
print("stop")
control$timer<-Inf
#session$timer<-reactiveTimer(intervalMs = Inf, session = getDefaultReactiveDomain())
})
## when reset button is pressed (set everything to original values, plus set seed)
observeEvent(input$reset,{
control$resetindicator<-0
control$count= 0
})
# ## depth plot output
output$DepthGraph <- renderPlot({
eqdepthdata.df <- input.df[(input.df$DayTimeID <= control$max & input.df$DayTimeID >= control$min), ]
ggplot(data.df, aes(x = DateTime, y = -1*AverageDepth_km)) +
geom_point() +
scale_color_manual(values = c("darkorange")) +
labs(title = "Average depth of earthquakes", x = "", y = "Depth (km)") +
ylim(-40, 0) +
theme_light() +
theme(text = element_text(size = 14)) +
theme(axis.text.x = element_text(angle = 45, hjust = 1))
})
## visual data outputs
output$Date<-renderText({
paste("Date:", input.df$DateTime[input.df$DayTimeID == control$count-1])
})
}
shinyApp(ui = ui, server = server)
CSV example is
DayTimeID,Date, Time, DateTime, AverageDepth_km
0, 20/08/20, 0:00, 20/08/20 0:00, 17
1, 20/08/20, 4:00, 20/08/20 4:00, 8
2, 20/08/20, 8:00, 20/08/20 8:00, 14
3, 20/08/20, 12:00, 20/08/20 12:00, 3
4, 20/08/20, 16:00, 20/08/20 16:00, 5
5, 20/08/20, 20:00, 20/08/20 20:00, 9
I was trying to update a parameter for the interval by updating the parameter. I was following code presented here https://nhsrcommunity.com/blog/animating-a-graph-over-time-in-shiny/ but if press play->pause->play but the time interval goes twice as fast as if I understand you create another reactiveTimer.
Any assistance would be appreciated.