s.image {ade4} | R Documentation

## Graph of a variable using image and contour

### Description

performs a scatterplot

### Usage

    s.image(dfxy, z, xax = 1, yax = 2, span = 0.5, xlim = NULL, ylim = NULL,
      kgrid = 2, scale = TRUE, grid = FALSE, addaxes = FALSE, cgrid = 0,
      include.origin = FALSE, origin = c(0, 0), sub = "", csub = 1,
      possub = "topleft", neig = NULL, cneig = 1, image.plot = TRUE,
      contour.plot = TRUE, pixmap = NULL, contour = NULL, area = NULL,
      add.plot = FALSE)

### Arguments

`dfxy` | a data frame containing the two columns for the axes
`z` | a vector of values on the `dfxy` rows
`xax` | the column number of x in `dfxy`
`yax` | the column number of y in `dfxy`
`span` | the parameter alpha which controls the degree of smoothing
`xlim` | the ranges to be encompassed by the x-axis, if NULL they are computed
`ylim` | the ranges to be encompassed by the y-axis, if NULL they are computed
`kgrid` | a number of points used to locally estimate the level line through the nodes of the grid, used by `kgrid*sqrt(length(z))`
`scale` | if TRUE, data are centered and reduced
`grid` | if TRUE, the background grid is traced
`addaxes` | a logical value indicating whether the axes should be plotted
`cgrid` | a character size, parameter used with par("cex")* `cgrid` to indicate the mesh of the grid
`include.origin` | a logical value indicating whether the point "origin" should be belonged to the graph space
`origin` | the fixed point in the graph space, for example c(0,0) the origin axes
`sub` | a string of characters to be inserted as legend
`csub` | a character size for the legend, used with `par("cex")*csub`
`possub` | a string of characters indicating the sub-title position ("topleft", "topright", "bottomleft", "bottomright")
`neig` | an object of class `neig`
`cneig` | a size for the neighbouring graph lines used with `par("lwd")*cneig`
`image.plot` | if TRUE, the image is traced
`contour.plot` | if TRUE, the contour lines are plotted
`pixmap` | an object 'pixmap' displayed in the map background
`contour` | a data frame with 4 columns to plot the contour of the map : each row gives a line (x1,y1,x2,y2)
`area` | a data frame of class 'area' to plot a set of surface units in contour
`add.plot` | if TRUE uses the current graphics window

### Author(s)

Daniel Chessel chessel@biomserv.univ-lyon1.fr

### Examples

    if (require(splancs, quiet = TRUE)){
       wxy=data.frame(expand.grid(-3:3,-3:3))
       names(wxy)=c("x","y")
       z=(1/sqrt(2))*exp(-(wxy$x^2+wxy$y^2)/2)
       par(mfrow=c(2,2))
       s.value(wxy,z)
       s.image(wxy,z)
       s.image(wxy,z,kgrid=5)
       s.image(wxy,z,kgrid=15)
    }

    ## Not run:
    data(t3012)
    if (require(splancs, quiet = TRUE)){
        par(mfrow = c(4,4))
        for(k in 1:12)  s.image(t3012$xy,scalewt(t3012$temp[,k]), kgrid = 3)
        par(mfrow = c(1,1))
    }

    data(elec88)
    if (require(splancs, quiet = TRUE)){
       par(mfrow = c(4,4))
       for(k in 1:12)
       s.image(t3012$xy, scalewt(t3012$temp[,k]), kgrid = 3, sub = names(t3012$temp)[k],
            csub = 3, area = elec88$area)
        par(mfrow = c(1,1))
    }
    ## End(Not run)

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