[R] Problems of data processing

[Florent Bonneu]

Indeed,
X <- c(1,Na,2,3,3,3,6,6)
Y <- c(1,Na,9,7,7,7,8,8)

I want to obtain one line for each Num. It's not a problem if there are 
several lines for the same place, because my identifier is Num. I just 
want to get X and Y well-informed in an other line for the same place. 
For example, "Num=2" is at the place "x1", like "Num=1", but we don't 
have the coordinates X and Y for "Num=2".  Now, the same coordinates are 
well-informed for "Num=1", so i want to retrieve this coordinates in my 
line "Num=2" for my columns X and Y.



Jacques VESLOT wrote:

> something wrong in X and Y definitions... but this could work:
>
> do.call("rbind", lapply(split(toto, toto$Num),
>    function(x) x[which.min(as.POSIXct(strptime(toto$Date, "%d/%m/%y 
> %H:%M"))),]))
>
> i don't understand the second query; do you want to keep the first 
> line when there are several lines for the same place ?
>
>
> Florent Bonneu a écrit :
>
>> I have two problems for the data processing of my large data base 
>> (50000 rows). For example, a sample is as follows
>>
>> Num <- c(1,2,3,4,4,4,5,5)
>> Date <- c("1/1/04 0:48","1/1/04 1:52", "1/1/04 1:55", "1/1/04 2:14", 
>> "1/1/04 3:09", "1/1/04 8:02", "1/1/04 9:05", "1/1/04 9:06")
>> Place <- c("x1","x1","x3","x4","x4","x4","x5","x5")
>> X <- c(1,””,2,3,3,3,6,6)
>> Y <- c(1,””,9,7,7,7,8,8)
>>
>> toto <- data.frame(Num,Date,Place,X,Y)
>>
>> The first problem is to keep one line for each Num with the “minimum” 
>> date. I managed to do it with loops but i would like a solution 
>> without using loops. It will be better for my large data base.
>>
>> The other one is to retrieve the coordinates ill-informed. For 
>> example, for the same place “x1”, Num=2 doesn't have X and Y. But, we 
>> have this information for Num=1.
>>
>> The example data base must be like this
>>
>> Num <- c(1,2,3,4,5)
>> Date <- c("1/1/04 0:48","1/1/04 1:52", "1/1/04 1:55", "1/1/04 2:14", 
>> "1/1/04 9:05")
>> Place <- c("x1","x1","x3","x4","x5")
>> X <- c(1,1,2,3,6)
>> Y <- c(1,1,9,7,8)
>>
>> toto <- data.frame(Num,Date,Place,X,Y) 
>>
>> Somebody know how to do ?
>> Thanks.
>>
>> Florent Bonneu
>> Laboratoire de Statistique et Probabilités
>> bureau 148  bât. 1R2
>> Université Toulouse 3
>> 118 route de Narbonne - 31062 Toulouse cedex 9
>> bonneu at cict.fr <mailto:bonneu at cict.fr>
>>
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>>
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