I don't think it is that simple because it is not a one-to-one match. In
the arr data frame, there are many arrivals in a quarter hour with good
weather on a given day. So I need to match the date and the quarter hour.
And all of the rows in the weather data frame are times with good
weather--unique date + quarter hour. That is why I needed the loop. For
each date and quarter hour in weather, I want to mark all the entries
with the corresponding date and weather as TRUE in the arr$gw column.
I did convert the dates to POSIXlt dates and rewrote my function as
gooddates = function(all, good) {
la = length(all) # All the arrivals
lw = length(good) # The good 15-minute periods
for(j in 1:lw) {
d=good$Date[j]
q=good$quarter[j]
all$gw[all$Date==d && all$quarter==q]=TRUE
}
}
Now it runs with no errors, but none of the 0s (FALSE) in arr$gw get
replaced with 1s. So I am still doing something wrong.
Thanks,
Jim
On 1/16/10 6:11 PM, jim holtman wrote:
> If you have a vector of the quarter hours of good weather (gw), then
> to create the column in the arr dataframe you would do
>
> arr$GoodWeather <- arr$quarter %in% gw
>
> This says that if the quarter hour of the arrival is in the 'gw'
> vector, set the value TRUE; otherwise FALSE.
>
>
> On 1/16/10 4:26 PM, Stephan Kolassa wrote:
> > Hi,
> >
> > it looks like when you read in your data.frames, you didn't tell
> R to
> > expect dates, so it treats the Date columns as factors.
> Judicious use
> > of something along these lines before doing your comparisons
> may help:
> >
> > arr$Date <- as.Date(as.character(arr$Date),format=something)
> >
> > Then again, it may be possible to do the actual merging using
> merge().
> >
> > HTH
> > Stephan
> >
> >
> > James Rome schrieb:
> >> I have two data frames. One (arr) has all arrivals to an
> airport for a
> >> year, and the other (gw) has the dates and quarter hour of the
> day when
> >> the weather is good. arr has a Date and quarter hour column.
> >>
> >>> names(arr)
> >> [1] "Date" "weekday" "hour" "month"
> >> "minute" [6] "quarter" "ICAO" "Flight"
> >> "AircraftType"
> >> "Tail" [11] "Arrived" "STA" "Runway"
> >> "FromTo" "Delay" [16] "Operator" "gw"
> >> I added the gw column to arr and initialized it to all FALSE
> >>
> >>> names(gw)
> >> [1] "Date" "minute" "hour"
> >> "quarter" [5] "Efficiency.Val" "Weekly.Avg"
> >> "Arrival.Val" "Weekly.Avg.1" [9] "Departure.Val"
> >> "Weekly.Avg.2" "Num.of.Hold" "Runway" [13] "Weather"
> >> First point of confusion:
> >>> gw[1,1]
> >> [1] 1/1/09
> >> 353 Levels: 1/1/09 1/1/10 1/10/09 1/10/10 1/11/09 1/11/10
> 1/12/09 ...
> >> 9/9/09
> >> Why do I get 353 levels?
> >>
> >> I am trying to identify the quarter hours with good weather in
> the arr
> >> data frame. What I want to do is to go through the rows in gw,
> and to
> >> set arr$gw to TRUE if arr$Date and arr$quarter match those in
> the gw
> >> row.
> >>
> >> So I tried
> >> gooddates = function(all, good) {
> >> la = length(all) # All the flights
> >> lw = length(good) # The good 15-minute periods
> >> for(j in 1:lw) {
> >> d=good$Date[j]
> >> q=good$quarter[j]
> >> all[all$DateTime==d && all$quarter==q,17]=TRUE
> >> }
> >> }
> >>
> >> but when I run this, I get
> >> "Error in Ops.factor(all$DateTime, d) :
> >> level sets of factors are different"
> >>
> >> I know the level sets are different, that is what I am trying
> to find.
> >> But I think I am comparing single elements from the data frames.
> >>
> >> So what am I doing wrong? And there ought to be a better way to
> do this.
> >>
> >> Thanks in advance,
> >> Jim Rome
> >>
> >> ______________________________________________
> >> R-help@r-project.org <mailto:R-help@r-project.org> mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-help
> >> PLEASE do read the posting guide
> >> http://www.R-project.org/posting-guide.html
> <http://www.r-project.org/posting-guide.html>
> >> and provide commented, minimal, self-contained, reproducible code.
> >>
> >
>
> ______________________________________________
> R-help@r-project.org <mailto:R-help@r-project.org> mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> <http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>
>
>
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem that you are trying to solve?
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