Approval of US presidents

The following line is not really necessary, it is used here only to indicate that presidents is a pre-installed data example.

data(presidents)

The data contains quarterly data about presidents’ popularity. The function tsp() contains the time series properties: the starting point, the end point and the frequency in which the popularity is measured within years.

tsp(presidents)

[1] 1945.00 1974.75    4.00

With the functions start(), end() and frequency() we can obtain the respective time series properties.

start(presidents)

[1] 1945    1

end(presidents)

[1] 1974    4

frequency(presidents)

[1] 4

presidents[1:12]

 [1] NA 87 82 75 63 50 43 32 35 60 54 55

window(presidents,
       start=1945,
       end=c(1947,4))

     Qtr1 Qtr2 Qtr3 Qtr4
1945 NA   87   82   75  
1946 63   50   43   32  
1947 35   60   54   55  

nixon <- window(presidents,
                start=1969,
                end=c(1974,2))
nixon

     Qtr1 Qtr2 Qtr3 Qtr4
1969 59   65   65   56  
1970 66   53   61   52  
1971 51   48   54   49  
1972 49   61   NA   NA  
1973 68   44   40   27  
1974 28   25            

plot(nixon)
/book/data-management-r/07-dates-times-timeseries/presidents-timeseries/6d75ac126de72c1b25ee3d963c30360f51cbed84f52d83e85227c192c80e0393.png 
time(nixon)

     Qtr1    Qtr2    Qtr3    Qtr4   
1969 1969.00 1969.25 1969.50 1969.75
1970 1970.00 1970.25 1970.50 1970.75
1971 1971.00 1971.25 1971.50 1971.75
1972 1972.00 1972.25 1972.50 1972.75
1973 1973.00 1973.25 1973.50 1973.75
1974 1974.00 1974.25