[R] Help with Centroids

[Robert David Burbidge]

# construct the dataframe
`TK-QUADRANT` <- c(9161,9162,9163,9164,10152,10154,10161,10163)
LAT <- 
c(55.07496,55.07496,55.02495,55.02496,54.97496,54.92495,54.97496,54.92496)
LON <- 
c(8.37477,8.458109,8.37477,8.45811,8.291435,8.291437,8.374774,8.374774)
df <- data.frame(`TK-QUADRANT`=`TK-QUADRANT`,LAT=LAT,LON=LON)

# group the data and calculate means by group
df$group <- floor(df$TK.QUADRANT/10)*10
out <- aggregate(df[c('LAT','LON')],by=list(df$group),mean)
print(out)

# see also:
# 
https://livefreeordichotomize.com/2018/06/27/bringing-the-family-together-finding-the-center-of-geographic-points-in-r/

Rgds,
Robert
On 14/11/2018 11:13, sasa kosanic wrote:
>  Dear Robert,
> Thank  you for your very much for your reply. Please see attached pdf  
> fille.
> I hope now it is more clear what I am trying to do:
> calculate new latitude and  longitude  of the centroids from the 
> existing cells...
> as you can see from the attached pdf.  from Lat/ Long of 
> 9161,9162,9163,9164 I need to calculate a single Lat/Long that could 
> be fore example called 9160
> and then from lat/ long of 10152 and 10154 a  new single lat/long 
> called 10150 .
> But guess I would need some kind of loop as this is just an example 
> table  and the the whole table is covering whole Germany.
> Please let me know if it is still not clear what I am trying to do here.
>
> Best wishes,
> Sasha
>
> On Wed, 14 Nov 2018 at 07:58, Robert David Burbidge 
> <robertburbidgedata using yahoo.co.uk 
> <mailto:robertburbidgedata using yahoo.co.uk>> wrote:
>
>     Hi Sasha,
>
>     Your attached table did not come through, please see the posting
>     guidelines:
>     "No binary attachments except for PS, PDF, and some image and archive
>     formats (others are automatically stripped off because they can
>     contain
>     malicious software). Files in other formats and larger ones should
>     rather be put on the web and have only their URLs posted. This way a
>     reader has the option to download them or not."
>     https://www.r-project.org/posting-guide.html
>
>     It is not clear what you are trying to do. As a first step it
>     looks like
>     you want something like:
>      >>>>>>>>>>>>>>>>
>     lat <- c(9161,9162,9163,9164,10152,10154)
>     floor(lat/10)*10
>     <<<<<<<<<<<<<<<<
>
>     Please provide further details on what you are trying to do.
>
>     Rgds,
>
>     Robert
>
>
>     On 13/11/2018 09:51, sasa kosanic wrote:
>     > Dear All, I am pretty new to R and would appreciate a help how to
>     > calculate centroids from the latitude and longitude of existing
>     cells
>     > (e.g. to get centroid for a new cell I would need to combine
>     latitude
>     > and 9161,9162,9163,9164 to 9160 or 10152, 10154 to 10150 etc.)
>     Please
>     > see attached table. Thank you very much! Best, Sasha
>
>
>
> -- 
>
> Dr Sasha Kosanic
> Ecology Lab (Biology Department)
> Room M644
> University of Konstanz
> Universitätsstraße 10
> D-78464 Konstanz
> Phone: +49 7531 883321 & +49 (0)175 9172503
>
> http://cms.uni-konstanz.de/vkleunen/
> https://tinyurl.com/y8u5wyoj
> https://tinyurl.com/cgec6tu
>
>

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