[R-sig-Geo] Convert data.frame/SpatialPointsDataFrame to raster

[Miluji Sb]

Dear Vijay and Hugo,

Thank you very much for your help. I will look into setting the number
row/cols!

Sincerely,

Milu

On Thu, Aug 1, 2019 at 5:12 PM Vijay Lulla <vijaylulla using gmail.com> wrote:

> I second Hugo's suggestion.  IMO, since your points are not a regular grid
> you will be unable to use `rasterXYZ`.  The only thing I would add to
> Hugo's answers is that you can set the number of rows/cols that you wish in
> your final raster by setting various args in the raster function.
> example(rasterize) has some good examples.
> HTH,
> Vijay.
>
> On Thu, Aug 1, 2019 at 4:44 AM Hugo Costa <hugoagcosta using gmail.com> wrote:
>
>> Dear Milu,
>>
>> the best I can suggest is something like this.
>>
>> library(raster)
>> df<-read.csv("path/to/data/downloaded/from/GoogleDrive")
>> try <- subset(df, year==2010)
>>
>> sp<-SpatialPointsDataFrame(try[,1:2],data=try, proj4string =
>> CRS("+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs"))
>>
>> r<-rasterize(sp, y=raster(), field=try$TWL_5, fun=mean, background=NA)
>> plot(r)
>>
>> Hope this helps somehow
>> Good luck
>> Hugo
>>
>> Miluji Sb <milujisb using gmail.com> escreveu no dia quinta, 1/08/2019 à(s)
>> 09:13:
>>
>>> Dear Vijay,
>>>
>>> Thank you again for your reply. I tried attaching my data for two years
>>> and
>>> two variables but the message was rejected. I have saved the data on a
>>> Google Drive folder here
>>> <
>>> https://drive.google.com/drive/folders/15LvLysXqIIua8ukkp8UNEnlJMSK6mA1K?usp=sharing
>>> >.
>>> Hope this will work. Thanks again!
>>>
>>> Sincerely,
>>>
>>> Milu
>>>
>>> On Thu, Aug 1, 2019 at 9:52 AM Miluji Sb <milujisb using gmail.com> wrote:
>>>
>>> > Dear Vijay,
>>> >
>>> > Thank you again for your reply. I have attached my data for two years
>>> and
>>> > two variables. Hope they will go through, otherwise the files are also
>>> > available here
>>> > <
>>> https://drive.google.com/drive/folders/15LvLysXqIIua8ukkp8UNEnlJMSK6mA1K?usp=sharing
>>> >.
>>> > Thanks again!
>>> >
>>> > Sincerely,
>>> >
>>> > Milu
>>> >
>>> > On Wed, Jul 31, 2019 at 10:46 PM Vijay Lulla <vijaylulla using gmail.com>
>>> wrote:
>>> >
>>> >> Hmm...I had seen your data and thought that it was just some sample
>>> that
>>> >> you'd shared.  If this is your whole data then I don't know how to
>>> create a
>>> >> raster from just one row that is returned from subsetting the
>>> dataframe.
>>> >>
>>> >> Sorry for the noise.
>>> >>
>>> >> On Wed, Jul 31, 2019 at 4:16 PM Miluji Sb <milujisb using gmail.com> wrote:
>>> >>
>>> >>> Hello,
>>> >>>
>>> >>> Thank you for your kind reply.  Here is a snapshot of the original
>>> data.
>>> >>> I had pasted it at the bottom of my first email but forgot to
>>> mention it.
>>> >>> Thanks again!
>>> >>>
>>> >>> df <- structure(list(lon = c(180, 179.762810919291, 179.523658017568,
>>> >>> 179.311342656601, 179.067616041778, 178.851382109362,
>>> 178.648816406322,
>>> >>> 178.501097394651, 178.662722495847, 178.860599151485), lat =
>>> >>> c(-16.1529296875,
>>> >>> -16.21659020822, -16.266117894201, -16.393550535614,
>>> -16.4457378034442,
>>> >>> -16.561653799838, -16.6533087696649, -16.7741069281329,
>>> >>> -16.914110607613,
>>> >>> -16.9049389730284), nsdec = structure(c(1L, 3L, 4L, 5L, 6L, 7L,
>>> >>> 8L, 9L, 10L, 2L), .Label = c("1 of 10", "10 of 10", "2 of 10",
>>> >>> "3 of 10", "4 of 10", "5 of 10", "6 of 10", "7 of 10", "8 of 10",
>>> >>> "9 of 10"), class = "factor"), TWL_5 = c(2.13810426616849,
>>> >>> 2.16767864033646,
>>> >>> 2.16881240361846, 2.20727073247015, 2.27771608519709,
>>> 2.3649601141941,
>>> >>> 2.44210984856767, 2.52466349543977, 2.63982954290745,
>>> 2.71828906773926
>>> >>> ), TWL_50 = c(2.38302354555823, 2.43142793944275, 2.45733044901087,
>>> >>> 2.53057109758284, 2.61391337469939, 2.71040967066483,
>>> 2.82546443373866,
>>> >>> 2.9709907727849, 3.1785797371187, 3.33227647990861), TWL_95 =
>>> >>> c(2.63753852023063,
>>> >>> 2.7080249053612, 2.75483681166049, 2.86893038433795,
>>> 2.97758282474101,
>>> >>> 3.14541928966618, 3.3986143008625, 3.68043269045659,
>>> 4.09571655859075,
>>> >>> 4.57299670034984), year = c(2010, 2020, 2030, 2040, 2050, 2060,
>>> >>> 2070, 2080, 2090, 2100)), row.names = c(NA, 10L), class =
>>> "data.frame")
>>> >>>
>>> >>> Sincerely,
>>> >>>
>>> >>> Milu
>>> >>>
>>> >>> On Wed, Jul 31, 2019 at 9:20 PM Vijay Lulla <vijaylulla using gmail.com>
>>> >>> wrote:
>>> >>>
>>> >>>> ?`rasterFromXYZ` states that "x and y represent spatial coordinates
>>> and
>>> >>>> must be on a regular grid."  And, it appears to me that you might
>>> be losing
>>> >>>> values by rounding lon/lat values.  The help file further suggests
>>> that
>>> >>>> `rasterize` might be the function you're looking for.  List members
>>> will
>>> >>>> (certainly I will) find it more helpful to propose other solutions
>>> if you
>>> >>>> post a small reproducible example of your original georeferenced
>>> dataset so
>>> >>>> that we get an idea of what data you're using.
>>> >>>>
>>> >>>> Sorry, I cannot be of more help.
>>> >>>>
>>> >>>> On Wed, Jul 31, 2019 at 10:45 AM Miluji Sb <milujisb using gmail.com>
>>> wrote:
>>> >>>>
>>> >>>>> Dear all,
>>> >>>>>
>>> >>>>> I have georeferenced dataset with multiple variables and years. The
>>> >>>>> data is
>>> >>>>> at ~100 km (1° × 1°) spatial resolution. I would like to convert
>>> this
>>> >>>>> into
>>> >>>>> a raster.
>>> >>>>>
>>> >>>>> I have filtered the data for one year and one variable and did the
>>> >>>>> following;
>>> >>>>>
>>> >>>>> try <- subset(df, year==2010)
>>> >>>>> try <- try[,c(1,2,4)]
>>> >>>>> try$lon <- round(try$lon)
>>> >>>>> try$lat <- round(try$lat)
>>> >>>>> r_imp <- rasterFromXYZ(try)
>>> >>>>>
>>> >>>>> Two issues; is it possible to convert the original dataset with the
>>> >>>>> multiple variables and years to a raster? If not, how can I avoid
>>> >>>>> rounding
>>> >>>>> the coordinates? Currently, I get this error "Error in
>>> >>>>> rasterFromXYZ(try) :
>>> >>>>> x cell sizes are not regular" without rounding.
>>> >>>>>
>>> >>>>> Any help will be greatly appreciated. Thank you!
>>> >>>>>
>>> >>>>> Sincerely,
>>> >>>>>
>>> >>>>> Shouro
>>> >>>>>
>>> >>>>> ## Data
>>> >>>>> df <- structure(list(lon = c(180, 179.762810919291,
>>> 179.523658017568,
>>> >>>>> 179.311342656601, 179.067616041778, 178.851382109362,
>>> 178.648816406322,
>>> >>>>> 178.501097394651, 178.662722495847, 178.860599151485), lat =
>>> >>>>> c(-16.1529296875,
>>> >>>>> -16.21659020822, -16.266117894201, -16.393550535614,
>>> -16.4457378034442,
>>> >>>>> -16.561653799838, -16.6533087696649, -16.7741069281329,
>>> >>>>> -16.914110607613,
>>> >>>>> -16.9049389730284), nsdec = structure(c(1L, 3L, 4L, 5L, 6L, 7L,
>>> >>>>> 8L, 9L, 10L, 2L), .Label = c("1 of 10", "10 of 10", "2 of 10",
>>> >>>>> "3 of 10", "4 of 10", "5 of 10", "6 of 10", "7 of 10", "8 of 10",
>>> >>>>> "9 of 10"), class = "factor"), TWL_5 = c(2.13810426616849,
>>> >>>>> 2.16767864033646,
>>> >>>>> 2.16881240361846, 2.20727073247015, 2.27771608519709,
>>> 2.3649601141941,
>>> >>>>> 2.44210984856767, 2.52466349543977, 2.63982954290745,
>>> 2.71828906773926
>>> >>>>> ), TWL_50 = c(2.38302354555823, 2.43142793944275, 2.45733044901087,
>>> >>>>> 2.53057109758284, 2.61391337469939, 2.71040967066483,
>>> 2.82546443373866,
>>> >>>>> 2.9709907727849, 3.1785797371187, 3.33227647990861), TWL_95 =
>>> >>>>> c(2.63753852023063,
>>> >>>>> 2.7080249053612, 2.75483681166049, 2.86893038433795,
>>> 2.97758282474101,
>>> >>>>> 3.14541928966618, 3.3986143008625, 3.68043269045659,
>>> 4.09571655859075,
>>> >>>>> 4.57299670034984), year = c(2010, 2020, 2030, 2040, 2050, 2060,
>>> >>>>> 2070, 2080, 2090, 2100)), row.names = c(NA, 10L), class =
>>> "data.frame")
>>> >>>>>
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