3.2 Customizing the plot

The command 'hart' selects the usage of contour lines, bitmaps or both and is discussed in the next section. Here we want to concentrate on commands used to change contour lines. The base level, the interval and the number of contour line levels are defined using the command 'hlin':

    hlin 1,100,50,10
    hlin 2,10,10,9,%

KUPLOT supports multiple sets of contour lines, e.g. one set at low levels to display diffuse scattering and one set at higher levels with a different spacing for the stronger Bragg peaks. Each set can be plotted in a different colour. The two example commands above illustrate the 'hlin' command. The first command sets the values for contour line set 1. The contours start at a value of 100 and increase in steps of 50. A total of 10 contour levels is drawn, e.g. the highest level corresponds to 600. The second 'hlin' commands sets values for the second contour line set, but the additional parameter '%' indicates, that the numbers are taken as percentage of $\Delta z = zmax - zmin$ of all loaded data sets rather than absolute z-values. In our example the base level is 10% of $\Delta z$, the contour lines are stepped in 10% intervals and 9 levels are plotted. Thus the highest level corresponds to 100%. The command 'hpak' determines how many contour line sets are actually plotted. The default is the usage of all sets defined by the 'hlin' command. Colour and line type for the individual contour line sets can be changed using the commands 'hcol' and 'htyp'.

  

Figure 3.2: Customizing contour plots

Sometimes a specific aspect ratio of the x- and y-axis or a specific angle between the two axis is required to obtain a non distorted picture of the data. KUPLOT allows the user to specify an aspect ration using the 'aver' command. As default KUPLOT determines the aspect ratio is such a way, that the resulting plot is as large as possible. This default can be restored by entering the command 'aver' without further parameters. Alternatively, the desired ratio can be given as parameter to the 'aver' command. In Figure 3.2 we show an example of a contour plot illustrating some of the features discussed above. The commands used to create the contour lines shown are listed below:

      1  aver 0.707
      2  angl 75.0
      3  #
      4  hlin 1, 10,10, 9
      5  hlin 2,120,20,10
      6  hcol 1,1,3
      7  hcol 1,2,1
      8  hlab 1,2

In line 1 we set the aspect ratio of the x- and y-axis to $1/\sqrt{2} \approx 0.707$ and the angle between the axes to a value of 75$^{\circ}$(line 2). In lines 4-5 we define two contour line packages, the first one giving contour lines at values of z_c = 10, 20, ..., 100 the second one at values z_c = 120, 140, ..., 320. In line 6 the colour for the first contour package for data set one is set to pen 3 (blue). Next the colour for the second package for the same data set is set to pen 1 (red). Finally the labelling of contour lines for data set one is enabled. The second parameter in line 8 specifies that every second contour line starting from the base line is labelled. As always, check the online help for more detailed information on the commands used.