CODEWITHSUNDEEP
rplottime-seriesforecastingtimeserieschart
Mayur
Mayur

Reputation: 179

change axis/scale for time series plot after forecast

I'm struggling with changing the x-axis (time) for my time series forecast plot. I have ran many models but I am struggling with the same issue. I'm going to write the code for the model fit, forecast and the plot here for one of the models. First here is my original time series. Note: I'm fitting my model on my training data that is from 2008-2016 and testing my model on my test data for the 11 months in 2017.

enter image description here

Data Split.

sal.ts <- window(sal.ts.original, start=c(2008,1), end=c(2016,12))
sal.test <- window(sal.ts.original, start=c(2017,1))

Now, the model.

sal.hw.mul <- HoltWinters(sal.ts, seasonal = "mult")
sal.hw.mul
fc.hwm <- forecast(sal.hw.mul, h=11)
fc.hwm
plot(fc.hwm, xlim=c(2017,2017+11/12), main = "Forecast from Mutltiplicative HW", xlab = "Year", ylab = "Total Sales, $M")
lines(sal.test,col='red', lwd=2)
legend("topleft", c("Actual", "Predicted"), col = c(4,2), lty = 1)

Here's my forecast plot: enter image description here

See that ugly 2017.0, 2017.2.... 2017.8? I want it to instead say 1,2,3,....11 for the 11 months of 2017.

Yes, I only want to plot my test data and forecast on it and not the whole series.

I am pretty sure my problem is around my use of the xlim function. I am using that xlim function to just plot the months of 2017 and if I don't use that then R plots the whole series from 2008-2017. I tried to play around with the axis function a lot by setting xaxt="n" in the plot command but still couldn't figure it out.

Let me know if you need more information from me. Any help will be appreciated.

Update, on someone's suggestion I tried to write a custom axis by setting xaxt = 'n' in my plot. Here's the change in code. 

x <- seq(1,11,1)
fc.hwm <- forecast(sal.hw.mul, h=11)
fc.hwm
layout(1:1)
plot(fc.hwm, xaxt='n', xlim=c(2017,2017+11/12), main = "Forecast from Mutltiplicative HW", xlab = "Year", ylab = "Total Sales, $M")
axis(side=1, at= x, labels=c("1","2","3","4","5","6","7","8","9","10","11"))
lines(sal.test,col='red', lwd=2)
legend("topleft", c("Actual", "Predicted"), col = c(4,2), lty = 1)

enter image description here

Like you can see. It gets me there half way. I can remove my current axis label but I am not being able to write a new axis. This new code is not even giving me an error or else I would've tried to debug it. It accepts my code but doesn't give me the desired output.

Upvotes: 0

Views: 2919

Answers (1)

aftonsteps
aftonsteps

Reputation: 11

Here's an idea. I'm not sure what the data look like, but I'm guessing that you have a Date type for the date variable -- and that means that your "by" sequence of integer 1 to 11 might be placing those new labels outside the plot limits. Try using a Date sequence instead.

Change this: x <- seq(1,11,1)

To something like this: x <- seq.Date(as.Date("2017-01-01"), as.Date("2017-11-01"), "months")

I'm not sure how far into November your data go, so you might want to set that "to" Date in the sequence to December instead, so you can fully cover your November data points.

Upvotes: 1

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