[R] how to merge within range?

[David Winsemius]

On May 14, 2011, at 2:27 PM, William Dunlap wrote:

> You could use findInterval() along with a trick with c(rbind(...)):
>
>> i <- findInterval(x=df.1$time, vec=c(rbind(df.2$from, df.2$to)))
>> i
> [1] 1 1 1 2 3 3 3 5 5 6

That's nice. I was working on a slightly different "trick"

findInterval( df.1[,1],t(df.2[,1:2]))
  [1] 1 1 1 2 3 3 3 5 5 6

I was then trying to get the right indices with (.)'%%' 2 and (.) '%/ 
%' 2


> The even-valued outputs would map to NA's, the odds
> to value[(i+1)/2], but you can use the c(rbind(...)) trick again:
>
>> c(rbind(df.2$value, NA))[i]
> [1]  1  1  1 NA  3  3  3  5  5 NA

I'd like to understand that. Maybe, maybe... ah, got it. At first I  
didn't realize those were the final answers since they looked like  
indices. My t(.) trick doesn't generalize as well.


My earlier suggestion tht two merges woul do it was based on my  
erroneous interpretation of the example, since  I thought the task was  
to match on the end points of the intervals.

>
> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com
>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org
>> [mailto:r-help-bounces at r-project.org] On Behalf Of René Mayer
>> Sent: Saturday, May 14, 2011 11:06 AM
>> To: David Winsemius
>> Cc: r-help at r-project.org
>> Subject: Re: [R] how to merge within range?
>>
>> thanks David and Ian,
>> let me make a better example as the first one was flawed
>>
>> df.1=data.frame(round((1:10)*100+rnorm(10)), value=NA)
>> names(df.1) = c("time", "value")
>> df.1
>>    time value
>> 1   101    NA
>> 2   199    NA
>> 3   301    NA
>> 4   401    NA
>> 5   501    NA
>> 6   601    NA
>> 7   700    NA
>> 8   800    NA
>> 9   900    NA
>> 10 1000    NA
>>
>> # from and to define ranges within time,
>> # note that from and to may not match the numbers given in time
>> df.2=data.frame(from=c(99,500,799),to=c(303,702,950), value=c(1,3,5))
>> df.2
>>   from  to value
>> 1   99 303     1
>> 2  500 702     3
>> 3  799 950     5
>>
>> what I want is:
>>    time value
>> 1   101    1
>> 2   199    1
>> 3   301    1
>> 4   401    NA
>> 5   501    3
>> 6   601    3
>> 7   700    3
>> 8   800    5
>> 9   900    5
>> 10 1000    NA
>>
>> @David I don't know what you mean by 2 merges,
>> René
>>
>>
>>
>>
>>
>> Zitat von "David Winsemius" <dwinsemius at comcast.net>:
>>
>>>
>>> On May 14, 2011, at 9:16 AM, Ian Gow wrote:
>>>
>>>> If I assume that the third column in data.frame.2 is named
>> "val" then in
>>>> SQL terms it _seems_ you want
>>>>
>>>> SELECT a.time, b.val FROM data.frame.1 AS a LEFT JOIN
>> data.frame.2 AS b ON
>>>> a.time BETWEEN b.start AND b.end;
>>>>
>>>> Not sure how to do that elegantly using R subsetting/merge,
>>>
>>> Huh? It's just two merge()'s (... once you fix the error in
>> the example.)
>>>
>>> -- 
>>> David
>>>
>>>> but you might
>>>> try a package that allows you to use SQL, such as sqldf.
>>>>
>>>>
>>>> On 5/14/11 8:03 AM, "David Winsemius"
>> <dwinsemius at comcast.net> wrote:
>>>>
>>>>>
>>>>> On May 14, 2011, at 8:12 AM, René Mayer wrote:
>>>>>
>>>>>> Hello,
>>>>>> how can one merge
>>>>>
>>>>> And what happened when you typed:
>>>>>
>>>>> ?merge
>>>>>
>>>>>> two data frames when in the second data frame one column
>> defines the
>>>>>> start values
>>>>>> and another defines the end value of the to be merged range.
>>>>>> data.frame.1
>>>>>> time ...
>>>>>> 13
>>>>>> 24
>>>>>> 35
>>>>>> 46
>>>>>> 55
>>>>>> ...
>>>>>> data.frame.2
>>>>>> start end
>>>>>> 24 37 ?h? ?
>>>>>> ...
>>>>>>
>>>>>> should result in this
>>>>>> 13 NA
>>>>>> 24 ?h?
>>>>>> 35 ?h?
>>>>>> 46 NA
>>>>>> 55
>>>>>> ?
>>>>>
>>>>> And _why_ would that be?
>>>>>
>>>>>
>>>>>> thanks,
>>>>>> René
>>>>>>
>>>>>> ______________________________________________
>>>>>> R-help at 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
>>>>> West Hartford, CT
>>>>>
>>>>> ______________________________________________
>>>>> R-help at 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
>>> West Hartford, CT
>>>
>>>
>>
>> ______________________________________________
>> R-help at 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
West Hartford, CT