On Jan 17, 2010, at 12:37 PM, James Rome wrote:
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
You are attempting a vectorized test and assignment with "&&" which
seems unlikely to succeed, but even then I am not sure your problems
would be over. (I'm also guessing that you might not have reported a
warning.)
Why not merge arr to gw by date and quarter?
Answering these questions would be greatly speeded up with a small
sample dataset. Are you aware of the virtues of the dput function?
--
David
}
}
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
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______________________________________________
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?
[[alternative HTML version deleted]]
______________________________________________
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
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
