Re: [R] How to order or sort a data.frame

From: Dimitrios Rizopoulos <Dimitris.Rizopoulos_at_med.kuleuven.be>
Date: Tue 15 Aug 2006 - 04:36:43 EST

Quoting John Kane <jrkrideau@yahoo.ca>:

>
> --- Dimitrios Rizopoulos
> <Dimitris.Rizopoulos@med.kuleuven.be> wrote:
>
>> try the following:
>>
>> mdf <- data.frame(us.state, count, year, month)
>> mdf[order(mdf$year, mdf$month), ]
>>
>
>
> Thansk to Dimitris and Dieter. This has helped since
> seems to have shown me a way around the problem. It
> just means that I have to sort the data earlier.
>
> What my example did not show clearly is that when I
> subset the data the variable 'month' which is numeric
> in the original dataframe becomes a factor. I was
> wondering if there was a way to sort the factor so
> that I would get a numeric sort. So far I have not
> been able to see how to coerce the factor "month" into
> a numeric when using 'order"

for converting factors to numeric check R FAQ 7.10.

Best,
Dimitris

>
> Thanks for helpl.
>
> Hi Hadley,
> I have not had time to check out the reshape but
> thanks.
>
>
>
>
>> Ph.D. Student
>> Biostatistical Centre
>> School of Public Health
>> Catholic University of Leuven
>>
>> Address: Kapucijnenvoer 35, Leuven, Belgium
>> Tel: +32/(0)16/336899
>> Fax: +32/(0)16/337015
>> Web: http://med.kuleuven.be/biostat/
>>
>>
> http://www.student.kuleuven.be/~m0390867/dimitris.htm
>>
>>
>> Quoting John Kane <jrkrideau@yahoo.ca>:
>>
>> > I have a dataframe where I would like to order
>> first
>> > by variable, year, and then within that variable
>> by
>> > month.
>> >
>> > So far the only way that I have seen to do this is
>> to
>> > order by year and then subset year and sort by
>> month
>> > and then do an rbind to get things back together.
>> >
>> > Is this the right approach?
>> >
>> > Example:
>> >
>> > us.state <-rep("California", 23)
>> >
>> > count <-
>> c(774,283,774,283,508,283,774,283,602,283,
>> >
>> > 774,508,0,602,330,283,283,283,602,301,126, NA,301)
>> >
>> > year <- c(2002, 2003, 2001, 2002, 2001, 2002,
>> 2001,
>> > 2002, 2002, 2003,
>> > 2002, 2002, 2001, 2002, 2001, 2002,
>> 2001,
>> > 2002, 2001, 2002,
>> > 2001, 2001, 2002)
>> >
>> > month <- c( 1, 1, 10, 10, 11, 11, 12, 12,
>> >
>> > 2, 2, 3, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9,
>> 9,
>> > 9)
>> >
>> >
>> >
>> >
>> > df <- data.frame (cbind(us.state,count, year,
>> month))
>> >
>> > # ordering as a factor works here
>> >
>> > df1 <- df[order(df$year),]
>> >
>> > df1
>> >
>> >
>> >
>> > df2 <- subset(df1, year==2001)
>> >
>> >
>> >
>> > # ordering as a factor works but not a good
>> > appearance.
>> >
>> >
>> > df3 <- df2[order(as.numeric(df2$month)),]
>> >
>> > df3
>> >
>> >
>> >
>> > This works but "month" is ordered as a factor
>> and I
>> > would prefer to coerce it into a numeric for
>> > presentation purposes but
>> > df3 <- df2[order(as.numeric(df2$month)),] does
>> not
>> > seem to work, nor has a couple of other things
>> I've
>> > tried.
>> >
>> > Any suggestions gratefully received.
>> >
>> > ______________________________________________
>> > R-help@stat.math.ethz.ch 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.
>> >
>> >
>>
>>
>>
>> Disclaimer:
>> http://www.kuleuven.be/cwis/email_disclaimer.htm
>>
>>
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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>
>

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