[R-sig-Geo] help: krigged map do not show colours
Jon Skoien
jon.skoien at jrc.ec.europa.eu
Tue Aug 4 14:55:17 CEST 2015
Anand,
I could not open your .grd file in R, I think the .gri file is missing.
However, looking at it in a text editor, and comparing with your
R-script, it seems something went wrong with your projections. Your
.csv-file has LatLong coordinates, but you are setting the projection to
"+proj=utm +zone=40 +south +datum=WGS84 +units=m +no_defs +ellps=WGS84
+towgs84=0,0,0", the same as you seem to have in your prediction raster.
But you need to reproject your observations in this case.
# First set the right projection:
proj4string(carbon_seq) <- CRS("+init=epsg4326") # epsg-code for latlong
# Then transform
carbon_seq = spTransform(carbon_seq, CRS("+proj=utm +zone=40 +south
+datum=WGS84 +units=m +no_defs +ellps=WGS84 +towgs84=0,0,0"))
If you do this, your prediction grid should overlap your observations,
and the colors should reflect your color ramp. What you essentially did
before was to make a prediction thousands of km away from your
observations, and then all values will be the same.
Best wishes,
Jon
On 8/4/2015 12:48 PM, Anand Sookun wrote:
> Dear Jon and Roman
>
> Thanks for the reply.
>
> Im attaching the code.
>
> You may be right that the variogram may be problematic but it fitted
> well visually.
>
> I think also that the prediction grid was not well created. I wiould be
> grateful to have to hints.code how to create a useful grid and also for
> the spplot or other alternatives
>
> I can send more info if required.
>
> Cheers
>
> Anand
>
> On Tue, Aug 4, 2015 at 1:39 PM, Jon Skoien <jon.skoien at jrc.ec.europa.eu
> <mailto:jon.skoien at jrc.ec.europa.eu>> wrote:
>
> Hi,
>
> You have attached some data, but we still dont know exactly what you
> do with the data (do you use the logarithm, how many bins, did you
> project the data set...?). However, having had a quick look using
> the LatLong coordinates (not really recommended), I can see that the
> variogram from this data set is not particularly well defined, and
> it could well be that you fitted a model with pure nugget effect. In
> that case you will get the same prediction everywhere and no color
> differences.
>
> Have a look at
> > summary(map)
> and particularly the summary of var1.pred.
> You could also plot the variogram of the data together with your
> model, vmf, and see how they fit.
>
> I am not sure what you mean by not being able to create a prediction
> grid with data included. Do you mean that you want a grid which
> exactly overlays some of the data points? Matching one point should
> not be difficult, 2 and 3 should be possible, but you might get some
> problems with precision (FAQ 7.31).
>
> Best wishes,
> Jon
>
>
>
>
> On 8/3/2015 5:30 PM, Anand Sookun wrote:
>> Hi
>>
>> Thank you Roman for your kind response.
>>
>> The data is as attached which is part of the whole dataset.
>>
>> My other problem is that im not able to create an appropriate
>> prediction grid with some data included.
>>
>> The codes which failed to show colour ramps are
>>
>> map <- krige(logcarbseq ~ 1, locations = carbon_seq, newdata =
>> map,model = vmf)
>> str(map)
>> print(spplot(map, "var1.pred", asp=1,
>> col.regions=bpy.colors(64),main="OK prediction, carbon"))
>> print(spplot(map, "var1.var",col.regions=cm.colors(64),asp=1,
>> main="OK prediction variance, carbon"))
>>
>> I look forward to hopefully get some solutions.
>>
>> Thanks again and warm regards
>>
>> Anand
>>
>> On Mon, Aug 3, 2015 at 4:09 PM, Roman Luštrik
>> <roman.lustrik at gmail.com <mailto:roman.lustrik at gmail.com>> wrote:
>>
>> What is the variability of the plotted variable?
>>
>> Cheers,
>> Roman
>>
>> On Sun, Aug 2, 2015 at 11:03 AM, Anand Sookun
>> <<mailto:asookun at gmail.com>asookun at gmail.com
>> <mailto:asookun at gmail.com>> wrote:
>>
>> Hi
>>
>> I have kriged my data but the map shows uniform colours -
>> no gradual
>> contour colour plot on map
>>
>> code: print(spplot(k40, "var1.pred", asp=1,
>> col.regions=bpy.colors(64),main="OK prediction, log-ppm Zn"))
>>
>> thnaks for any help
>>
>> Anand Sookun
>> --
>> -------------------------------------------------------
>> *Anand Sookun (**MPhil. **PhD Candidate, University of
>> Mauritius)*
>> *Director cum Freelance Consultant*
>> *Soft Sustainable Services (Mauritius)*
>> *Research and Consultancy*
>>
>> Website: http://sustain-ability.webs.com/
>>
>>
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>>
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>> /*Anand Sookun (*//*MPhil. *//*PhD Candidate, University of
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>> /*Director cum Freelance Consultant*/
>> /*Soft Sustainable Services (Mauritius)*/
>> /*Research and Consultancy*/
>>
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>> <http://sustain-ability.webs.com/>http://sustain-ability.webs.com/
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>
> --
> Jon Olav Skøien
> Joint Research Centre - European Commission
> Institute for Environment and Sustainability (IES)
> Climate Risk Management Unit
>
> Via Fermi 2749, TP 100-01, I-21027 Ispra (VA), ITALY
>
> jon.skoien at jrc.ec.europa.eu <mailto:jon.skoien at jrc.ec.europa.eu>
> Tel:+39 0332 789205 <tel:%2B39%200332%20789205>
>
> Disclaimer: Views expressed in this email are those of the individual and do not necessarily represent official views of the European Commission.
>
>
>
>
> --
> -------------------------------------------------------
> /*Anand Sookun (*//*MPhil. *//*PhD Candidate, University of Mauritius)*/
> /*Director cum Freelance Consultant*/
> /*Soft Sustainable Services (Mauritius)*/
> /*Research and Consultancy*/
>
> Website: http://sustain-ability.webs.com/
>
>
> https://www.linkedin.com/profile/view?id=161468467&trk=nav_responsive_tab_profile_pic
>
--
Jon Olav Skøien
Joint Research Centre - European Commission
Institute for Environment and Sustainability (IES)
Climate Risk Management Unit
Via Fermi 2749, TP 100-01, I-21027 Ispra (VA), ITALY
jon.skoien at jrc.ec.europa.eu
Tel: +39 0332 789205
Disclaimer: Views expressed in this email are those of the individual
and do not necessarily represent official views of the European Commission.
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