R Time Series plot.ts()

Question

I am trying to read in a time series and do a plot.ts(), however I am getting weird results. Perhaps I did something wrong. I tried including the start and end dates but the output is still wrong. Any help appreciated. Thank you.

This is the code and output:

sales1 <- read.csv("TimeS.csv",header=TRUE)
sales1

salesT <- ts(sales1)
salesT
plot.ts(salesT)

output:
> sales1 <- read.csv("TimeS.csv",header=TRUE)
> sales1

  year  q1  q2  q3  q4
1 1991 4.8 4.1 6.0 6.5
2 1992 5.8 5.2 6.8 7.4
3 1993 6.0 5.6 7.5 7.8
4 1994 6.3 5.9 8.0 8.4

> salesT <- ts(sales1)
> salesT

Time Series:
Start = 1 
End = 4 
Frequency = 1 
  year  q1  q2  q3  q4
1 1991 4.8 4.1 6.0 6.5
2 1992 5.8 5.2 6.8 7.4
3 1993 6.0 5.6 7.5 7.8
4 1994 6.3 5.9 8.0 8.4

> plot.ts(salesT)

 It looks like I can't paste the plot.  instead of 1 graph it has 5 separate    
 plots stacked onto each other.

Answer 1

This line is making the times into one of the series which is unlikely what you want:

> salesT <- ts(sales1)

We need to transpose the data frame in order that it reads across the rows rather than down and we use c to turn the resulting matrix into a vector forming the data portion of the series. (continued after chart)

# create sales1
Lines <- "year  q1  q2  q3  q4
1 1991 4.8 4.1 6.0 6.5
2 1992 5.8 5.2 6.8 7.4
3 1993 6.0 5.6 7.5 7.8
4 1994 6.3 5.9 8.0 8.4"
sales1 <- read.table(text = Lines, header = TRUE)

# convert to ts and plot
salesT <- ts(c(t(sales1[-1])), start = sales1[1, 1], freq = 4)
plot(salesT)

Regarding the comment, if the data looks like this then it is more straight forward and the lines below will produce the above plot. We have assumed that the data is sorted and starts at the bginning of a year so we do not need to use the second column:

Lines2 <- "year qtr sales
1  1991  q1   4.8
2  1991  q2   4.1
3  1991  q3   6.0
4  1991  q4   6.5
5  1992  q1   5.8
6  1992  q2   5.2
7  1992  q3   6.8
8  1992  q4   7.4
9  1993  q1   6.0
10 1993  q2   5.6
11 1993  q3   7.5
12 1993  q4   7.8
13 1994  q1   6.3
14 1994  q2   5.9
15 1994  q3   8.0
16 1994  q4   8.4"
sales2 <- read.table(text = Lines2, header = TRUE)

salesT2 <- ts(sales2$sales, start = sales2$year[1], freq = 4)
plot(salesT2)

Update fixed. Added response to comments.

Answer 2

Try this

salesT<-ts(unlist(t(sales1[,-1])),start=c(1991,1),freq=4)

Answer 3

Here I think you need to format it correctly try this:

salesT <- ts(sales1)

ts.plot(salesT, frequency = 4, start = c(1991, 1), end = c(1994, 4)))

Answer 4

The format of the original data is difficult to use directly for a time series. You could try this instead:

sales1 <- t(sales1[,-1])
sales1 <- as.vector(sales1)
my_ts <- ts(sales1, frequency = 4, start=c(1991,1))
plot.ts(my_ts)