Error message: Non-numeric argument to mathematical function

[Dwayne Paschall]

I am trying to use a little function inside a shiny app. It works perfectly on my local machine. But when I upload it to shinyapps.io, I get the following error (from the shinyapps.io log files):

Error in round(frequency) : non-numeric argument to mathematical function

Its really just a simple filter operation:

highPassFilter <- function(x) {

     alpha1 <- (cos(.707*2*pi/48)+sin(.707*2*pi/48)-1)/cos(.707*2*pi/48)

     HP <- (1-alpha1/2)*(1-alpha1/2)*(x-2*lag(x)+lag(x,2))

     HP <- HP[-c(1,2)]

     HP <- filter(HP, c(2*(1-alpha1), -1*(1-alpha1)*(1-alpha1)), method="recursive")

     HP <- c(NA, NA, HP)

     HP <- xts(HP, order.by=index(x))

     return(HP)

}

Any hint at why it works locally but not on the shinyapps server?

many thanks,

d