cut methods for stars objects

Source: R/factors.R

cut methods for stars objects

# S3 method for array
cut(x, breaks, ...)

# S3 method for matrix
cut(x, breaks, ...)

# S3 method for stars
cut(x, breaks, ...)

Arguments

x

see cut
breaks

see cut
...

see cut

Value

an array or matrix with a levels attribute; see details

Details

R's factor only works for vectors, not for arrays or matrices. This is a work-around (or hack?) to keep the factor levels generated by cut and use them in plots.

Examples

tif = system.file("tif/L7_ETMs.tif", package = "stars")
x = read_stars(tif)
cut(x, c(0, 50, 100, 255))

#> stars object with 3 dimensions and 1 attribute
#> attribute(s):
#>     L7_ETMs.tif    
#>  (0,50]   :156060  
#>  (50,100] :503764  
#>  (100,255]: 77264  
#> dimension(s):
#>      from  to  offset delta                       refsys point values x/y
#> x       1 349  288776  28.5 UTM Zone 25, Southern Hem... FALSE   NULL [x]
#> y       1 352 9120761 -28.5 UTM Zone 25, Southern Hem... FALSE   NULL [y]
#> band    1   6      NA    NA                           NA    NA   NULL    
cut(x[,,,1], c(0, 50, 100, 255))

#> stars object with 3 dimensions and 1 attribute
#> attribute(s):
#>     L7_ETMs.tif    
#>  (0,50]   :     1  
#>  (50,100] :117134  
#>  (100,255]:  5713  
#> dimension(s):
#>      from  to  offset delta                       refsys point values x/y
#> x       1 349  288776  28.5 UTM Zone 25, Southern Hem... FALSE   NULL [x]
#> y       1 352 9120761 -28.5 UTM Zone 25, Southern Hem... FALSE   NULL [y]
#> band    1   1      NA    NA                           NA    NA   NULL    
plot(cut(x[,,,1], c(0, 50, 100, 255)))

#> downsample set to c(0,0,1)
tif = system.file("tif/L7_ETMs.tif", package = "stars")
x1 = read_stars(tif)
(x1_cut = cut(x1, breaks = c(0, 50, 100, Inf)))  # shows factor in summary

#> stars object with 3 dimensions and 1 attribute
#> attribute(s):
#>     L7_ETMs.tif    
#>  (0,50]   :156060  
#>  (50,100] :503764  
#>  (100,Inf]: 77264  
#> dimension(s):
#>      from  to  offset delta                       refsys point values x/y
#> x       1 349  288776  28.5 UTM Zone 25, Southern Hem... FALSE   NULL [x]
#> y       1 352 9120761 -28.5 UTM Zone 25, Southern Hem... FALSE   NULL [y]
#> band    1   6      NA    NA                           NA    NA   NULL    
plot(x1_cut[,,,c(3,6)]) # propagates through [ and plot

#> downsample set to c(1,1,1)