When I run sqldf to merge two datasets, it's changing the Date (class date)
to a numeric value (class factor). Not sure why. Appreciate any insight.
Console output for two datasets and the merged dataset (via sqldf) listed
below.
> summary(df.aggregate)
Date Hour x
Min. :2010-07-01 0 : 64 Min. : 0.00
1st Qu.:2010-07-25 1 : 64 1st Qu.: 1.00
Median :2010-08-16 2 : 64 Median : 9.00
Mean :2010-08-16 3 : 64 Mean :11.77
3rd Qu.:2010-09-08 4 : 64 3rd Qu.:23.00
Max. :2010-09-30 5 : 64 Max. :32.00
(Other):1152
> class(df.aggregate$Date)
[1] "Date"
> summary(df.possible.combos)
Date Hour
Min. :2010-07-01 Min. : 0.00
1st Qu.:2010-07-25 1st Qu.: 5.75
Median :2010-08-16 Median :11.50
Mean :2010-08-16 Mean :11.50
3rd Qu.:2010-09-08 3rd Qu.:17.25
Max. :2010-09-30 Max. :23.00
> class(df.possible.combos$Date)
[1] "Date"
> #merge raw data and all possible combinations
> df.final <- sqldf('select Date, Hour, x as RoomsInUse from
> "df.possible.combos"
+ left join "df.aggregate" using (Hour, Date)')
> summary(df.final)
Date Hour RoomsInUse
14791.0: 24 Min. : 0.00 Min. : 0.00
14792.0: 24 1st Qu.: 5.75 1st Qu.: 1.00
14796.0: 24 Median :11.50 Median : 9.00
14797.0: 24 Mean :11.50 Mean :11.77
14798.0: 24 3rd Qu.:17.25 3rd Qu.:23.00
14799.0: 24 Max. :23.00 Max. :32.00
(Other):1392
> class(df.final$Date)
[1] "factor"
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