Exporting forecast to a dataset while running a loop - r

Question

I am trying to take one dataset and run a forecast on it based on different cutoffs. The for i runs, but it ends up saying "replacement has 76 rows, data has 0"
Here is the replicable example:
library(tidyverse)
library(forecast)
library(scales)
library(growthcurver)
options(scipen = 12) # Scientific Notation
options(digits = 6) # Specify Digits
noup<-3 #Days without update
claims <- tribble(~perdaycases, 3,1,1,0,0,0,
1,8, 7, 2,
8, 8, 12,
13, 15,
21, 27,
47, 65,
47, 30,
62, 74,
23, 38)
claims$cases <- cumsum(claims$perdaycases)
claims$id<-1:nrow(claims)
inds <- seq(as.Date("2020-03-11"), as.Date(Sys.Date()-noup), by = "day")
set.seed(1)
## Forecast length
h0 = 30
#Here, I create the empty dataset
estimates<-data.frame(Simulation=numeric(),Forecast=numeric()) #Empty Dataset
for(i in 1:length(claims$id)) {
cap<-subset(claims,id<14+i) #First cutoff then it runs again
cts <- ts(cap$cases, start = 1,frequency = 365) #Time Series
cfore <- forecast(auto.arima(cts), h= h0, level = c(80)) #Do the Arima
gc_fit <- SummarizeGrowth(seq(1,nrow(cap)),cap$cases) #Fit the Growth curve
tt <- seq(from=nrow(cap)+1,to=90,by=1)
forelog <- predict(gc_fit$model,newdata=list(t=tt)) #Prediction
forecast<-forelog #Create the item with mean projection
len<-as.numeric(length(forecast)) #Length of each forecast
estimates$Simulation<-as.numeric(rep(i,len)) #id each iteration
estimates$Forecast<-forecast #Here I try to export the forecast
}
The Error I get is ...
Error in $<-.data.frame(*tmp*, "Simulation", value = c(1, 1, 1, 1, :
replacement has 76 rows, data has 0
I am guessing it has to do with the last 2 lines but after 4 hours of struggling I have decided to ask for help.
SOS.
Thanks,

Answer 1

Try to provide a minimal example that reproduces your error. Your problem boils down to this simple problem:
test <- data.frame(
a=numeric(),
b=numeric()
)
test$a <- c(1,2,3)
# Error in `$<-.data.frame`(`*tmp*`, a, value = c(1, 2, 3)) :
# replacement has 3 rows, data has 0
Which doesn't work. You could do something like this:
test <- data.frame(
a=numeric(),
b=numeric()
)
for (i in 1:3){
a <- c(rep(i, 3))
b <- c(rep(i-1, 3))
df <- data.frame(
a = a,
b = b
)
test <- bind_rows(test,df)
}
And for your specific example, you could replace the following lines:
# estimates$Simulation <-as.numeric(rep(i,len)) #id each iteration
# estimates$Forecast<-forecast #Here I try to export the forecast
df <- data.frame(
Simulation = as.numeric(rep(i,len)),
estimates = forecast
)
estimates <- bind_rows(estimates,df)