Re: [R] duplicate values

From: Gabor Grothendieck <ggrothendieck_at_gmail.com>
Date: Sun, 16 Nov 2008 13:33:35 -0500

Here are three possibilities:

# 1
DF[!duplicated(DF$Datetime), ]

# 2
aggregate(DF[-1], DF[1], head, 1)

These give the first one but if you want the last one use the fromLast= arg of duplicated or tail instead of head with aggregate.

# 3
# The zoo package can read in data, convert the
# first column to datetime and remove
# duplicates via aggregation all at once:

Lines <- 'Datetime,Temperature

2008-6-1 00:00:00,5
2008-6-1 02:00:00,5
2008-6-1 03:00:00,6
2008-6-1 03:00:00,0
2008-6-1 04:00:00,6
2008-6-1 04:00:00,0
2008-6-1 05:00:00,7
2008-6-1 06:00:00,7 '

library(zoo)
library(chron)
# z <- read.zoo("myfile.csv", sep = ",", header = TRUE, FUN = as.chron, # aggregate = function(x) head(x, 1))

z <- read.zoo(textConnection(Lines), sep = ",", header = TRUE, FUN = as.chron,   aggregate = function(x) head(x, 1))

# or use tz = "" in place of FUN=as.chron if you want POSIXct. # See the three zoo vignettes and on dates and times see R News 4/1.

On Sun, Nov 16, 2008 at 1:10 PM, Antje Nöthlich <antno_at_web.de> wrote:
> Hei R Users,
>
> i have the following dataframe:
>
> Datetime Temperature and many more collumns
> 1 2008-6-1 00:00:00 5
> 2 2008-6-1 02:00:00 5
> 3 2008-6-1 03:00:00 6
> 4 2008-6-1 03:00:00 0
> 5 2008-6-1 04:00:00 6
> 6 2008-6-1 04:00:00 0
> 7 2008-6-1 05:00:00 7
> 8 2008-6-1 06:00:00 7
> . . .
> . . .
> . . .
> 3000 2008-8-31 00:00:00 3
>
>
> the problem is that row 3 & 4 and row 5 & 6 have the same "Datetime" value but they differ in the values of the "Temperature" column.
> Now for the whole dataframe i would like to delete rows that have the same "Datetime" value as the prior row.
> I have tried unique(dataframe), but it does not work here because the rows are no real duplicates of each other.
> thanks in advance for your help!
>
> Antje
>
> ______________________________________________
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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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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. Received on Sun 16 Nov 2008 - 18:36:04 GMT

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