Dear Jorge,

thank you very much for your help. So with() was missing. 

Tripstatistics=with(TripsData,aggregate(TripsData[,3:4],by=list(Trip=Tripmatch),FUN="mean"))

works.

Best wishes,

Juliane 

 Dr. Juliane Struve
Environmental Scientist
10, Lynwood Crescent
Sunningdale SL5 0BL
01344 620811 




________________________________
From: Jorge Ivan Velez <jorgeivanvelez@gmail.com>

Cc: R mailing list <r-help@r-project.org>
Sent: Thursday, 24 September, 2009 13:32:59
Subject: Re: [R] aggregate() - error message

Hi Julien, 

Works for me:

# Data sets
TripsData1 <- read.table(textConnection("Trip Distance TimeDiff Tripmatch
7329 35,36 172.7453   0.0041     35,36
7371 36,35 172.7453   0.0004     35,36
7372 35,36 172.7453   0.0000     35,36
7373 36,35 172.7453   0.0004     35,36
7374 35,36 172.7453   0.0001     35,36"), header = TRUE)

TripsData2 <- read.table(textConnection("Trip Distance TimeDiff Tripmatch 
1617 19,20 1087.365   0.0441     19,20
1899 20,19 1087.365   0.0207     19,20
1915 19,20 1087.365   0.0361     19,20
3285 20,19 1087.365   0.0356     19,20
3826 19,20 1087.365   0.0697     19,20"), header = TRUE)
closeAllConnections()

# Individually
with(TripsData1, aggregate(TripsData1[, 2:3], by = list(Tripmatch), FUN="mean") )
# Group.1 Distance TimeDiff
# 1   35,36 172.7453    0.001

with(TripsData2, aggregate(TripsData2[, 2:3], by = list(Tripmatch), FUN="mean") )
#  Group.1 Distance TimeDiff
# 1   19,20 1087.365  0.04124

# Combining both data sets
AllTrips <- rbind(TripsData1, TripsData2)
with(AllTrips, aggregate(AllTrips[, 2:3], by = list(Tripmatch), FUN="mean") )
# Group.1  Distance TimeDiff
# 1   35,36  172.7453  0.00100
# 2   19,20 1087.3650  0.04124

HTH,
Jorge


On Thu, Sep 24, 2009 at 8:23 AM, Juliane Struve <> wrote:

Dear all,
>
>
>thanks you very much for replying. However, this does not seem to solve the problem.
>I still get the same error message when using TripsData[,2:3].
>
>Is there anything else that could be wrong with this statement or the data ? What length is the error message referring to ?
>
>Many thanks,
>
>Juliane
>
>
> Dr. Juliane Struve
>Environmental Scientist
>10, Lynwood Crescent
>Sunningdale SL5 0BL
>01344 620811
>
>
>
>
>----- Original Message ----
>From: Paul Emberson <email@calidasoft.co.uk>

>Cc: r-help@r-project.org
>Sent: Thursday, 24 September, 2009 12:27:00
>Subject: Re: [R] aggregate() - error message
>
>Hi,
>
>Are you trying to get columns 2 and 3 from TripsData in which case you need to say TripsData[,2:3] ?
>
>Paul
>
>Juliane Struve wrote:
>> Dear list,
>>  would anybody be able to tell me why the statement  Tripstatistics=aggregate(TripsData[2:3],by=list(Trip=Tripmatch),FUN="mean")
>>  seems to work well with TripsData 1 but not with TripsData 2 ?
>>  With TripsData 2 it yields  Error in FUN(X[[1L]], ...) : arguments must have same length
>>
>> I can't see a difference in the two data sets. Could someone shed light on the error message ? Maybe that would help me figure out where the problem is.
>>  Thanks very much for any help.  Juliane  PS: The examples below contain the  first 5 rows  of my two datafiles.    TripsData 1
>>            Trip Distance TimeDiff Tripmatch
>> 7329 35,36 172.7453  0.0041    35,36
>> 7371 36,35 172.7453  0.0004    35,36
>> 7372 35,36 172.7453  0.0000    35,36
>> 7373 36,35 172.7453  0.0004    35,36
>> 7374 35,36 172.7453  0.0001    35,36
>>
>>  TripsData 2
>>              Trip Distance TimeDiff Tripmatch
>> 1617 19,20 1087.365  0.0441    19,20
>> 1899 20,19 1087.365  0.0207    19,20
>> 1915 19,20 1087.365  0.0361    19,20
>> 3285 20,19 1087.365  0.0356    19,20
>> 3826 19,20 1087.365  0.0697    19,20
>>
>>
>>
>>
>> ______________________________________________
>> 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.
>
>
>
>
>



      
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