# 2D histograms of 2 volumes The `histo.2D` function creates a "histo2D" class object, containing the two-dimensional array of histograms of two "volume" class objects that have the same grid. ```r histo.2D( x.vol, y.vol, x.breaks = NULL, y.breaks = NULL, include.outer = TRUE, alias = "", description = "" ) ``` ## Arguments - `x.vol, y.vol`: "volume" class objects. The 2 volumes must have the grid (i.e. share the same voxels location). - `x.breaks, y.breaks`: Vectors giving the breakpoints of x and y axes. See Details. - `include.outer`: Boolean. If `include.outer = TRUE`, the values out the `x.breaks` and `y.breaks` of each volume are counted in the first and the last cell of the histograms. They are not taken into account otherwise. - `alias`: Character string, `$alias` of the created object - `description`: Character string, describing the created object. ## Returns Returns a "histo2D" class object. This is a list including: * `$patient`: set to `x.vol$patient`. * `$patient.name`: set to `x.vol$patient.name`. * `$patient.bd`: set to `x.vol$patient.bd`. * `$patient.sex`: set to `x.vol$patient.sex`. * `$file.basename`: set to "". * `$file.dirname`: set to "". * `$object.name`: set to "". * `$object.alias`: alias of the histo2D object. * `$frame.of.reference`: set to `x.vol$frame.of.reference`. * `$ref.pseudo` : set to `x.vol$ref.pseudo`. * `$modality` : set to `"histo2D"`. * `$description`: description of the histo2D object. * `$creation.date`: set to `Sys.Date`. * `$nb.pixels`: number of elements in the `density.map`. * `$x.file.src`: set to x.vol$object.alias * `$y.file.src`: set to y.vol$object.alias * `x.breaks`: vector of x-axis breakpoints. * `y.breaks`: vector of y-axis breakpoints. * `x.mids`: vector of x-axis cell centers. * `y.mids`: vector of y-axis cell centers. * `density.map`: array of densities. * `total.counts`: number of counted voxels. ## Details The arguments `x.breaks` and `y.breaks` represent the scales of the x and y axes of 2D-histogram graph. If they are `NULL`, the `histo.2D` function defaults to 256 cells between the values `vol$min.pixel` and `vol$max.pixel`. ## Examples ```r # loading of toy-patient objects (decrease dxyz for better result) step <- 4 patient <- toy.load.patient (modality = c("ct", "mr", "rtstruct"), roi.name = "brain", dxyz = rep (step, 3)) CT <- patient$ct[[1]] MR <- patient$mr[[1]] S <- patient$rtstruct[[1]] T.MAT <- patient$T.MAT # restriction of the volume around the RoI CT.on.roi <- nesting.roi (CT, S, roi.name = "brain", vol.restrict = TRUE, xyz.margin = c (1, 1, 1), alias = CT$description) MR.on.CT <- vol.regrid (vol = MR, back.vol = CT.on.roi, interpolate = TRUE, T.MAT = T.MAT, alias = CT$description, description = NULL) # selection of voxels included in the RoI. roi.bin <- bin.from.roi (vol = CT.on.roi, struct = S, roi.sname = "brain", verbose = FALSE) MR.select <- vol.from.bin (MR.on.CT, roi.bin, alias = MR$description) CT.select <- vol.from.bin (CT.on.roi, roi.bin, alias = CT$description) # 2D histogram H2D <- histo.2D (MR.select, CT.select, x.breaks = seq (50, 400, 10), y.breaks = seq (50, 400, 10), alias = "H2D MR CT") str (H2D) ``` ## See Also display.2D.histo .

histo.2D function