ixyplot               package:IDPmisc               R Documentation

_I_m_a_g_e _S_c_a_t_t_e_r _P_l_o_t _f_o_r _L_a_r_g_e _D_a_t_a_s_e_t_s

_D_e_s_c_r_i_p_t_i_o_n:

     Produces an image scatter plot of large datasets where the colors
     encode the density of the points in the scatter plot. Works also
     with factors.

_U_s_a_g_e:

     ixyplot(x, y = NULL,
             pixs = 1, zmax = NULL, colramp = IDPcolorRamp, border = FALSE,
             xlab = NULL, ylab = NULL, nx.lab = 5, ny.lab = 5, minL.lab = 3,
             main = NULL, cex.main = par("cex.main"))

_A_r_g_u_m_e_n_t_s:

     x,y: Coordinates of points whose density should be plotted. If 'x'
          ist a matrix or a data.frame, the first two column are used
          as x and y respectively. 'y' must be in this case NULL. 'x'
          and 'y' may be numeric or factor variable. 

    pixs: Pixelsize in mm.

    zmax: Maximum counts per pixel to be plotted. 'zmax' must be >=
          maximum number of counts per pixel.

 colramp: Color ramp to encode the density of the points within a
          pixel.

  border: Shall border be drawn between the colors in the legend:
          'TRUE' / 'FALSE'.

    xlab: Label for x-axis.

    ylab: Label for y-axis.

  nx.lab: Approximate number of labeled ticks on x-axis.

  ny.lab: Approximate number of labeled ticks on y-axis.

minL.lab: The minimum length of the abbreviations of factor levels,
          used to label the axes.

    main: Title.

cex.main: Size of title relative to 'par("cex")'

_D_e_t_a_i_l_s:

     When there are factors present in the data.frame, the variables
     are reordered so that the factors are plotted in the left corner
     of the bottom.

     The idea is similar to 'plot.hexbin'. The hexagons are better
     suited to reflect the density of points in a plane than the
     squares used here. Nevertheless squares are, contrary to hexagons,
     invariant to reflexions at the x- _and_ y-axis and therefore
     suited for scatter plot matrices and also for plotting factors.

_V_a_l_u_e:

     Maximum number of counts per Pixel found.

_N_o_t_e:

     When you get the error message "Zmax too small! Densiest aereas
     are out of range!" you must run the function again without
     specifying zmax. The value returned gives you the minimum value
     allowed for zmax.

_A_u_t_h_o_r(_s):

     Andreas Ruckstuhl, refined by Rene Locher

_S_e_e _A_l_s_o:

     'ilagplot', 'ipairs', 'Image'

_E_x_a_m_p_l_e_s:

     x <-  rnorm(100000)
     y <- atan(rnorm(100000,0))
     ixyplot(x,y)
     ixyplot(x,pixs=2)
     ixyplot(iris[,1:2],pixs=4)
     ixyplot(iris[,"Petal.Width"],iris[,"Species"],pixs=4)
     ixyplot(x=iris[,"Species"],y=iris[,"Petal.Width"],pixs=4,border=TRUE,
             xlab="Species",
             ylab="Petal Width",
             main="Iris Species and Petal Width")

