[R-sig-Geo] question on the use of Leaflet for plotting points and rater GeoTIFF

[Gabriel Cotlier]

Dear Ben,

Thanks a lot for your help with the useful and appropriate link you sent
me. There was the solution for the flipping of the colorbar.
I could finally flip the color bar and it worked out correctly. I also
found a little bit less opaque color palette, that is the matlab "jet"
color in the R "matlab" package, but it is still a bit opaque for
my personal taste. I will give it some trials and errors with many
different opacities to see what happened.

Thanks a lot again for your helpful advice and guidance,

Kind regards,
Gabriel




On Fri, Aug 13, 2021 at 3:00 PM Ben Tupper <btupper using bigelow.org> wrote:

> Hi,
>
> I don't think we can run the code since it isn't reproducible (see
> https://CRAN.R-project.org/package=reprex
> <https://cran.r-project.org/package=reprex> for help with that.)  But
> here are some hints:
>
> flipped color bar - I love to use RSeek.org which is an R-centric search
> engine -  you may want to bookmark it or add it to your search engine list
> if your browser supports that. https://rseek.org/?q=leaflet+flip+color+bar
> This search hits a number of discussions on flipping the color bar.
>
> color intensity - oooooh, there is so much discussion in the world about
> colors.  By default raster images have opacity of 1 (fully opaque) when
> rendered in leaflet, so really it is a matter of finding the color table
> you want and then applying colorNumeric judiciously.  For me it comes down
> to trial and error.  If you are looking for eye pop! then perhaps check out
> the viridis options.  See ?colorNumeric
>
> Cheers,
> Ben
>
> On Thu, Aug 12, 2021 at 2:24 PM Gabriel Cotlier <gabiklm01 using gmail.com>
> wrote:
>
>> Dear Ben,
>>
>> Thanks a lot for your help!
>> Actually it worked very well for me with the link you gave me.
>> However, for some reason the numbers of the values in color scale goes
>> from the lower values set at the top  (blue) of the sacale to the
>> higher values set at the bottom (red ) and it would be better for me if it
>> goes from from the lower values in the bottom (blue) to higher value in the
>> top (red), since is temperature going from the lower to the higher.
>>  Another issue I found a bit problematic for me to modify is that the
>> color palette is too "light", for instance not like the color palette "Jet"
>> in Matlab or Python, it seems as if the intensity of the colors of the
>> temperature colors is low or light maybe is a transparency and should
>> change opacity ....?
>>
>> Maybe you or somebody knows a possible way to improve these two issues a
>> bit ?
>>
>> Here is the code :
>>
>> # color palettes
>> # pal <- colorNumeric(palette = "Spectral", values(raster), na.color =
>> "transparent" , reverse = TRUE)
>> pal <- colorNumeric(palette = "RdYlBu", values(raster), na.color =
>> "transparent" , reverse = TRUE)
>>
>> # plot map
>> leaflet() %>%
>>   addTiles(urlTemplate = "
>> https://mts1.google.com/vt/lyrs=s&hl=en&src=app&x={x}&y={y}&z={z}&s=G",
>> attribution = 'Google')  %>%
>>   addPolygons(data = polygon,weight=5,col = 'black')  %>%
>>   addCircles(data = points, color = "White", radius = 500, fillOpacity =
>> 1,opacity = 9)%>%
>>   addRasterImage(raster, project = FALSE, colors = pal) %>%
>>   addLegend(pal = pal, values = values(raster), title = "Temperature",
>> opacity = 9)  # ,labFormat = labelFormat(transform = function(x) sort(x,
>> decreasing = TRUE)))
>>
>> Thanks a lot again for your help.
>> Kind regards,
>> Gabriel
>>
>>
>> On Thu, Aug 12, 2021 at 5:07 PM Ben Tupper <btupper using bigelow.org> wrote:
>>
>>> Hi,
>>>
>>> See the "markers" and "raster images" sections here
>>> http://rstudio.github.io/leaflet/markers.html
>>>
>>> Cheers,
>>> Ben
>>>
>>> On Thu, Aug 12, 2021 at 5:02 AM Gabriel Cotlier <gabiklm01 using gmail.com>
>>> wrote:
>>>
>>>> Hello.
>>>>
>>>> I would like to use Leaflet package to plot over a Google Satellite base
>>>> map :
>>>>
>>>> 1.  a shapefile of polygon
>>>> 2.  a shapefile of points
>>>> 3,  a GeoTIFF image
>>>>
>>>> I could use the Leaflet package to get plotted successfully only the
>>>> first
>>>> Item of the list above with the following code :
>>>>
>>>> require(rgdal)
>>>> library(rgeos)
>>>> library(raster)
>>>>
>>>> shapeData <- raster::shapefile('Seattle_boundries.shp')
>>>> shapeData <- spTransform(shapeData, CRS("+proj=longlat +ellps=GRS80"))
>>>>
>>>> leaflet() %>%
>>>>   addTiles(urlTemplate = "
>>>> https://mts1.google.com/vt/lyrs=s&hl=en&src=app&x={x}&y={y}&z={z}&s=G",
>>>> attribution = 'Google')  %>%
>>>>   addPolygons(data=shapeData,weight=5,col = 'red')
>>>>
>>>> How is it possible to find a way to complete the code above for plotting
>>>> the item 2 and 3 as well in the same Leaflet figure.
>>>>
>>>> Is there any possible solution that can enable this task?
>>>>
>>>> Thanks for your help.
>>>>
>>>> Kind regards
>>>> Gabriel
>>>>
>>>>         [[alternative HTML version deleted]]
>>>>
>>>> _______________________________________________
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>>>> R-sig-Geo using r-project.org
>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>>
>>>
>>>
>>> --
>>> Ben Tupper (he/him)
>>> Bigelow Laboratory for Ocean Science
>>> East Boothbay, Maine
>>> http://www.bigelow.org/
>>> https://eco.bigelow.org
>>>
>>>
>
> --
> Ben Tupper (he/him)
> Bigelow Laboratory for Ocean Science
> East Boothbay, Maine
> http://www.bigelow.org/
> https://eco.bigelow.org
>
>

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