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

[Miluji Sb]

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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>>
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>
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