ChartDirector 7.0 (Python Edition)

Contour Color Scale


      

This example demonstrates using various color scales for contour charts.

ChartDirector supports two ways to configure the color scale:

This example includes 4 charts to demonstrate both of the above methods.

Source Code Listing

pythondemo\contourcolor.py
#!/usr/bin/python # The ChartDirector for Python module is assumed to be in "../lib" import sys, os sys.path.insert(0, os.path.join(os.path.abspath(sys.path[0]), "..", "lib")) from pychartdir import * def createChart(chartIndex) : # The x and y coordinates of the grid dataX = [-4, -3, -2, -1, 0, 1, 2, 3, 4] dataY = [-4, -3, -2, -1, 0, 1, 2, 3, 4] # Use random numbers for the z values on the XY grid r = RanSeries(99) dataZ = r.get2DSeries(len(dataX), len(dataY), -0.9, 0.9) # Create a XYChart object of size 420 x 360 pixels c = XYChart(420, 360) # Set the plotarea at (30, 25) and of size 300 x 300 pixels. Use semi-transparent grey # (0xdd000000) horizontal and vertical grid lines c.setPlotArea(30, 25, 300, 300, -1, -1, -1, 0xdd000000, -1) # Set the x-axis and y-axis scale c.xAxis().setLinearScale(-4, 4, 1) c.yAxis().setLinearScale(-4, 4, 1) # Add a contour layer using the given data layer = c.addContourLayer(dataX, dataY, dataZ) # Enable contour label by setting its style to black (000000) 8pt default bold font layer.setContourLabelStyle("bold", 8, 0x000000) # Set the label to display the value in a CDML block with semi-transparent white (4FFFFFFF) # background and 2 pixels left/right margin and 1 pixel top/bottom margin layer.setContourLabelFormat("<*block,bgcolor=4FFFFFFF,margin=2 2 1 1*>{value}") # Move the grid lines in front of the contour layer c.getPlotArea().moveGridBefore(layer) # Add a color axis (the legend) in which the top left corner is anchored at (350, 25). Set the # length to 400 300 and the labels on the right side. cAxis = layer.setColorAxis(350, 25, TopLeft, 300, Right) if chartIndex == 1 : # Speicify a color gradient as a list of colors, and use it in the color axis. colorGradient = [0x0044cc, 0xffffff, 0x00aa00] cAxis.setColorGradient(0, colorGradient) elif chartIndex == 2 : # Specify the color scale to use in the color axis colorScale = [-1.0, 0x1a9850, -0.75, 0x66bd63, -0.5, 0xa6d96a, -0.25, 0xd9ef8b, 0, 0xfee08b, 0.25, 0xfdae61, 0.5, 0xf46d43, 0.75, 0xd73027, 1] cAxis.setColorScale(colorScale) elif chartIndex == 3 : # Specify the color scale to use in the color axis. Also specify an underflow color 0x66ccff # (blue) for regions that fall below the lower axis limit. colorScale = [0, 0xffff99, 0.2, 0x80cdc1, 0.4, 0x35978f, 0.6, 0x01665e, 0.8, 0x003c30, 1] cAxis.setColorScale(colorScale, 0x66ccff) # Output the chart c.makeChart("contourcolor%s.png" % chartIndex) createChart(0) createChart(1) createChart(2) createChart(3)