Farley, Robert
2008-Oct-22 23:09 UTC
[R] newbie Syntax questions: Re-Calculating expansion factors
I have a dataframe with many hundreds of survey records containing:
tripid_nu, lineon, MuchOtherData, X1, X2, X3, X4
tripid_nu = identifier for each "Trip" {E.g. for EB MTA-901
leaving the first stop at 07:24}
lineon = identifier for each of the stop locations
Where X1 is the ratio (for each trip/stop combination) of some target
number to the number of records. This would sum to the proper trip
total if there were observations for every stop, but there are MANY
missing stops (no returned survey) for any trip. X2 is then the ratio
of the trip target (sum of X1 targets for each trip) and sum of X1 in
the dataframe for that tripid_nu.
I will soon receive corrected lineon values and new X1 (and hence trip)
targets. I'm trying to figure out how to program the subsequent
recalculations in R. I'm thinking that {schematically} it may look
something like this:
TargetX1Sums <- ##{read an external file of totals for tripid_nu/lineon,
How should I format the data?? Dataframe or matrix??}##
TargetX2Sums <- xtabs(~tripid_nu, data= TargetX1Sums)
InitX1Sums <- xtabs(~tripid_nu+lineon, data=SurveyData)
SurveyData$NewX1= ##{some formulation of TargetX1Sums/InitX1Sums,
selecting by tripid_nu/lineon }##
InitX2Sums <- xtabs(NewX1~tripid_nu, data=SurveyData)
SurveyData$NewX2= ##{some formulation of TargetX2Sums/InitX2Sums
selecting by tripid_nu }##
Am I thinking of this correctly? What data structures/classes should I
be using? What is the syntax for the type of calculation I'm trying to
do? How should I specify my new X1 target data file so I can use it
efficiently?
Does this make any sense?
Thanks in advance,
********************************
PS My preliminary dataframe subtotals look something like this:
> InitX1Sums <- xtabs(~tripid_nu+lineon data=SurveyData)
> InitX1Sums
lineon
tripid_nu Warner Center De Soto Pierce College Tampa Reseda Balboa
Woodley Sepulveda Van Nuys Woodman Valley College Laurel Canyon North
Hollywood
9011880 1 0 2 1 0 2
1 0 0 0 1 0
0
9011890 0 0 0 0 0 0
1 0 0 0 0 1
0
9011960 1 1 2 0 1 1
0 1 3 2 1 0
0
9011970 0 0 0 0 1 0
0 1 6 1 1 1
14
9012040 1 1 1 3 2 7
1 1 1 0 0 0
0
9012050 0 0 0 0 0 0
0 1 1 1 0 0
5
9012130 0 0 0 0 2 0
1 0 1 0 0 2
7
9012280 0 2 10 2 6 2
1 3 1 0 0 1
0
9012290 0 0 1 0 1 1
0 1 2 1 3 3
7
9012720 1 2 3 1 0 0
0 0 2 0 0 0
0
9012730 0 0 1 0 0 0
0 0 0 1 0 1
2
9012760 2 2 5 0 6 2
2 1 2 0 0 0
0
9012770 0 0 0 0 0 0
0 0 0 0 0 3
11
9012840 4 1 2 2 3 3
0 3 1 0 0 0
0
9012850 0 1 0 0 0 0
0 1 1 0 0 0
5
9012880 2 3 0 2 5 0
0 1 0 0 0 0
0
9012890 0 0 0 0 1 0
0 0 1 1 0 1
7
9013000 0 1 2 0 0 2
0 1 0 3 0 1
0
9013010 0 0 0 0 0 1
0 0 1 1 0 0
2
9013240 0 0 1 0 3 0
0 2 0 0 0 0
0
... and so on
********************************
Robert Farley
Metro
1 Gateway Plaza
Mail Stop 99-23-7
Los Angeles, CA 90012-2952
Voice: (213)922-2532
Fax: (213)922-2868
www.Metro.net
[[alternative HTML version deleted]]
Apparently Analagous Threads
Wisdom of the Ancients
