ursa (version 3.11.5)

colortable: Color Tables of raster images.

Description

Manipulation with color tables of raster images.

Usage

# S3 method for ursaColorTable
print(x, ...)
# S3 method for ursaColorTable
[(x, i)

ursa_colortable(x)
ursa_colortable(x) <- value
ursa_colorindex(ct)
   
ursa_color(ct, ...)
category_value(ct, name)
# S3 method for ursaColorTable
names(x)
# S3 method for ursaColorTable
names(x) <- value

Value

ursa_colortable returns value of $colortable element if ursaRaster object.

ursa_colortable<- returns ursaRaster object with modified $colortable element.

Class of $colortable element is “ursaColorTable”. This is named character vector, where names are categories, and values are “#RRGGBB” or R color names.

Extract function [] for ursaColorTable object returns object of class ursaColorTable.

Extract function names for ursaColorTable object returns character vector (names of categories).

Replace function names<- for ursaColorTable object returns ursaColorTable with changed names of categories.

ursa_colorindex returns index (if presents) for ursaColorTable object.

ursa_color returns character vector of colors in hex format.

catefory_value returns integer value, which is corresponded to index of color table or category table.

Color tables are written to ENVI header file.

Arguments

x

ursaRaster object. Extended for numeric (integer or real) of character vector.

ct

ursaColorTable object with or without indexing.

value

Named character vector. In Replacement functions:

For ursa_colortable(): values are colors in “#RRGGBB” notation or R color names (colors). names(value) are names of categories.

For names(): values are names of categories. If length of names is n-1, where n is length of colors, then intervaling is assumed, and value are assign to interval breaks.

i

Integer vector. Indices specifying elements to extract part (subset) of color table.

name

Character of length one. Name of category or name of colortable to get desired integer value stored in data.

...

In print(), passing to generic print. Currently not used.
In ursa_colortable(), passing to generic print. Currently not used.
In ursa_color(), passing to colorize.

Author

Nikita Platonov

Warning

If colors are specified as R color names, then slow down may appear.

Details

The example of the class structure

Class 'ursaColorTable'  Named chr [1:4] "#313695" "#BCE1EE" "#FDBE70" "#A50026"
  ..- attr(*, "names")= chr [1:4] "<= 450" "(450;550]" "(550;650]" "> 650"

It is recommended to use ursa_colortable and ursa_colortable<- instead of colortable and colortable<-. ursa_colortable and colortable are synonyms. ursa_colortable<- and colortable<- are synonyms too. Package raster contains colortable and colortable<- functions. colortable and colortable<- will be remove from this package if the case of frequent joint use of both packages.

If color tables describe continuous and non-intersecting intervals, then print gives additional line of extracted breaks.

See Also

colorize

Examples

session_grid(NULL)
print(methods(class="ursaColorTable"))

a <- pixelsize()
print(a)
b1 <- colorize(a,value=c(400,500,600,700),interval=FALSE)
b2 <- colorize(a,value=c(450,550,650)    ,interval=TRUE)
display(list(b1,b2))
print(is.ursa(a,"colortable"))
print(is.ursa(b1,"colortable"))
print(is.ursa(b2,"colortable"))
print(ursa_colortable(a))
print(ursa_colortable(b1))
print(ursa_colortable(b2))
ursa_colortable(b2) <- c("Low"="darkolivegreen1"
                        ,"Moderate"="darkolivegreen2"
                        ,"High"="darkolivegreen3"
                        ,"undefined"="darkolivegreen4")
print(ursa_colortable(b2))
names(ursa_colortable(b2))[4] <- "Polar"
print(ursa_colortable(b2))
display(b2)

lab <- sample(c("A","B","C"),9,replace=TRUE)
lab
ct <- ursa_color(lab)
names(ct) <- lab
ct
category_value(b2,"High")