Superimpose Several Geometric Patterns
Superimpose any number of point patterns or line segment patterns.
## S3 method for class 'ppp': superimpose(\dots, W=NULL, check=TRUE)
## S3 method for class 'psp': superimpose(\dots, W=NULL, check=TRUE)
## S3 method for class 'default': superimpose(\dots)
- Any number of arguments, each of which represents either a point pattern or a line segment pattern or a list of point patterns.
- Optional. Data determining the window for the resulting pattern.
Either a window (object of class
"owin", or something acceptable to
as.owin), or a function which returns a window,
- Logical value (passed to
pspas appropriate) determining whether to check the geometrical validity of the resulting pattern.
This function is used to superimpose several geometric patterns
of the same kind, producing a single pattern of the same kind.
superimpose is generic, with methods
for the class
ppp of point patterns, the class
of line segment patterns, and a default method. There is also
a method for
lpp, described separately in
The dispatch to a method is initially determined
by the class of the first argument in
default: If the first argument isnotan object of class
psp, then the default method
superimpose.defaultis executed. This checks the class of all arguments, and dispatches to the appropriate method. Arguments of class
ppplistcan be handled.
ppp: If the first
...argument is an object of class
pppthen the method
superimpose.pppis executed. All arguments in
...must be either
pppobjects or lists with components
y. The result will be an object of class
If the first
...argument is an object of class
pspmethod is dispatched and all
...arguments must be
pspobjects. The result is a
The patterns are not required to have the same window of observation.
The window for the superimposed pattern is controlled
by the argument
Wis a window (object of class
"W"or something acceptable to
as.owin) then this determines the window for the superimposed pattern.
NULL, or the character string
"none", then windows are extracted from the geometric patterns, as follows. For
superimpose.psp, all arguments
...are line segment patterns (objects of class
"psp"); their observation windows are extracted; the union of these windows is computed; and this union is taken to be the window for the superimposed pattern. For
superimpose.default, the arguments
...are inspected, and any arguments which are point patterns (objects of class
"ppp") are selected; their observation windows are extracted, and the union of these windows is taken to be the window for the superimposed point pattern. For
superimpose.defaultif none of the arguments is of class
"ppp"then no window is computed and the result of
Wis one of the strings
"bbox"then a window for the superimposed pattern is computed from the coordinates of the points or the line segments as follows.[object Object],[object Object],[object Object]
Wis a function, then this function is used to compute a window for the superimposed pattern from the coordinates of the points or the line segments. The function should accept input of the form
list(x,y)and is expected to return an object of class
"owin". Examples of such functions are
...may be marked patterns. The marks of each component pattern must have the same format. Numeric and character marks may be ``mixed''. If there is such mixing then the numeric marks are coerced to character in the combining process. If the mark structures are all data frames, then these data frames must have the same number of columns and identical column names.
If the arguments
... are given in the form
names will be used as an extra column of marks
attached to the elements of the corresponding patterns.
superimpose.ppp, a point pattern (object of class
superimpose.default, either a point pattern (object of class
"ppp") or a
superimpose.psp, a line segment pattern (object of class
# superimposing point patterns p1 <- runifrect(30) p2 <- runifrect(42) s1 <- superimpose(p1,p2) # Unmarked pattern. p3 <- list(x=rnorm(20),y=rnorm(20)) s2 <- superimpose(p3,p2,p1) # Default method gets called. s2a <- superimpose(p1,p2,p3) # Same as s2 except for order of points. s3 <- superimpose(clyde=p1,irving=p2) # Marked pattern; marks a factor # with levels "clyde" and "irving"; # warning given. marks(p1) <- factor(sample(LETTERS[1:3],30,TRUE)) marks(p2) <- factor(sample(LETTERS[1:3],42,TRUE)) s5 <- superimpose(clyde=p1,irving=p2) # Marked pattern with extra column marks(p2) <- data.frame(a=marks(p2),b=runif(42)) s6 <- try(superimpose(p1,p2)) # Gives an error. marks(p1) <- data.frame(a=marks(p1),b=1:30) s7 <- superimpose(p1,p2) # O.K. # how to make a 2-type point pattern with types "a" and "b" u <- superimpose(a = rpoispp(10), b = rpoispp(20)) # how to make a 2-type point pattern with types 1 and 2 u <- superimpose("1" = rpoispp(10), "2" = rpoispp(20)) # superimposing line segment patterns X <- rpoisline(10) Y <- as.psp(matrix(runif(40), 10, 4), window=owin()) Z <- superimpose(X, Y) # being unreasonable crud <- superimpose(p1,p2,X,Y) # Gives an error, of course!