R help - Aug 2020 - Error with sf ordinary kriging after creating grid

I want to perform ordinary kriging of temperature (UTCI) data in Nigeria with sf
and gstat packages. However, after fitting the variogram model and creating a
grid for the region, the krige function returns this error:

Error in (function (classes, fdef, mtable)  : 
  unable to find an inherited method for function ?krige? for signature
?"formula", "sfc_POINT"?
What am I doing wrong? Here is my code:

library(gstat)
library(sf)  
sf_data <- st_as_sf(x = data, coords = c("longitude",
"latitude"), crs = 4326)

#VARIOGRAM  
vgm_utci <- variogram(UTCI~1, sf_data)
utci_fit <- fit.variogram(vgm_utci, vgm("Mat"), fit.kappa = TRUE)
   
#CREATE GRID
nigeria <- read_sf("./Igismap/Nigeria_Boundary.shp")
nigeria <- nigeria$geometry
nigeria.grid <- nigeria %>% 
              st_make_grid(cellsize = 0.1, what = "centers") %>%
              st_intersection(nigeria)
            
#UTCI ORDINARY KRIGING
utci_krig <- krige(formula = sf_data$UTCI ~ 1, nigeria.grid, model =
utci_fit)
When plotted, the grid and the variogram model look fine. I have attached data
and shapefile. Thank you so much in advance,

Nicola

You should post on r-sig-geo, not here. The specific expertise you seek is
much more likely to be found there.

Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Thu, Aug 13, 2020 at 4:09 AM Nicola Gambaro <nicola at gambaro.co.uk>
wrote:
> I want to perform ordinary kriging of temperature (UTCI) data in Nigeria
> with sf and gstat packages. However, after fitting the variogram model and
> creating a grid for the region, the krige function returns this error:
>
> Error in (function (classes, fdef, mtable)  :
>   unable to find an inherited method for function ?krige? for signature
> ?"formula", "sfc_POINT"?
> What am I doing wrong? Here is my code:
>
> library(gstat)
> library(sf)
> sf_data <- st_as_sf(x = data, coords = c("longitude",
"latitude"), crs > 4326)
>
> #VARIOGRAM
> vgm_utci <- variogram(UTCI~1, sf_data)
> utci_fit <- fit.variogram(vgm_utci, vgm("Mat"), fit.kappa =
TRUE)
>
> #CREATE GRID
> nigeria <- read_sf("./Igismap/Nigeria_Boundary.shp")
> nigeria <- nigeria$geometry
> nigeria.grid <- nigeria %>%
>               st_make_grid(cellsize = 0.1, what = "centers")
%>%
>               st_intersection(nigeria)
>
> #UTCI ORDINARY KRIGING
> utci_krig <- krige(formula = sf_data$UTCI ~ 1, nigeria.grid, model >
utci_fit)
> When plotted, the grid and the variogram model look fine. I have attached
> data and shapefile. Thank you so much in advance,
>
> Nicola
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