The wckgraph Module

The wckgraph package is a simple graph library for the WCK toolkit. To display a diagram, first create a GraphWidget widget, and then add graph components to the diagram.

The following example draws a simple line diagram:

graph = wckgraph.GraphWidget(root)

data = xdata, ydata

graph.add(wckgraph.Axes(data))
graph.add(wckgraph.LineGraph(data))

The Axes component calculates a suitable viewport based on the data, and also draws the axis (including labels). The LineGraph component draws a line diagram into that viewport. You can use options to configure the axes and the graph components.

For details, see below.

Module Contents

_DrawContext(widget, bbox) (class) [#]

(Internal) Drawing context.

For more information about this class, see The _DrawContext Class.

AreaGraph(data, **options) (class) [#]

Area plot.

data: Input data, given as a tuple of two arrays (xdata, ydata).
**options: Plot options.
brush=: Brush object.

For more information about this class, see The AreaGraph Class.

Axes(data=None, **options) (class) [#]

Standard axes handling.

data: Graph data. If given, the class calculates the extent from the actual graph values. If not given, the extent is taken from the extent option.
**options: Axes options.
extent=: Graph extent.
grid=: Grid pen. If given, this should be a Pen object.
xaxis=: Where to draw the x-axis. Can be “bottom” or “none”. Default is “bottom”.
yaxis=: Where to draw the y-axis. Can be one of “left”, “right”, “both”, or “none”. Default is “left”.
xoffset=: Distance between the x-axis and the graph canvas. Defaults to 0.
yoffset=: Distance between the y-axis and the graph canvas. Defaults to 0.

For more information about this class, see The Axes Class.

BarGraph(data, **options) (class) [#]

Simple bar plot.

data: Input data, given as a tuple of two arrays (xdata, ydata). Both arrays should have the same length.
**options: Plot options.
brush=: Brush object to use when filling the bars. Use Brush(None) to draw hollow bars.
pen=: Pen object to use for the bar border. Use Pen(None) to draw bars without a border.
barwidth=: Relative barwidth. Defaults to 1.0 (100%).

For more information about this class, see The BarGraph Class.

Brush(color=”yellow”) (class) [#]

Brush object.

color=: Brush color.

For more information about this class, see The Brush Class.

GraphWidget(master, **options) (class) [#]

Graph widget.

master: Parent widget.
**options: Widget options.
background=: Widget background color.
font=: Widget font.
foreground=: Widget text color.
canvasbackground=: Graph canvas background color. Default is same as the widget background.
height=: Widget height (in pixels). Defaults to 600 pixels.
width=: Widget width (in pixels). Defaults to 400 pixels.

For more information about this class, see The GraphWidget Class.

LineGraph(data, **options) (class) [#]

Line plot.

data: Input data, given as a tuple of two arrays (xdata, ydata). Both arrays should have the same length, and the X array should be monotonically increasing (that is, xdata[i] < xdata[i+1] should be true for the entire array).
**options: Plot options.
pen=: Pen object to use when drawing the line. Defaults to a thin black line.
marker=: Marker object. If omitted, markers are not drawn.
interpolation=: Line interpolation method. Can be one of “linear”, “smooth”, “stairs”, “stem” or “step”. Defaults to “linear”.

For more information about this class, see The LineGraph Class.

Marker(style=”circle”, color=”blue”, border=”black”, size=5) (class) [#]

Marker object.

style=: Marker style. One of “circle”, “diamond”, “plus”, “square”, or “triangle”. Defaults to “circle”.
color=: Marker fill color. Use None to draw just the border.
border=: Marker border color.
size=: Marker size (radius), in pixels. Defaults to 5.

For more information about this class, see The Marker Class.

Pen(color=”black”, width=1) (class) [#]

Pen object.

color=: Pen color.
width=: Pen width.

For more information about this class, see The Pen Class.

ScatterGraph(data, **options) (class) [#]

Scatter (X-Y) plot.

data: Input data, given as a tuple of two arrays (xdata, ydata). Both arrays should have the same length.
**options: Plot options.
marker=: Marker object. This should be an instance of the Marker class. If omitted, a default marker style is used.

For more information about this class, see The ScatterGraph Class.

SimpleGraph(data, **options) (class) [#]

Base class for simple graphs.

data: Input data, given as a tuple of two arrays (xdata, ydata). Both arrays should have the same length.
**options: Plot options.

For more information about this class, see The SimpleGraph Class.

The _DrawContext Class

_DrawContext(widget, bbox) (class) [#]: (Internal) Drawing context. A fully populated instance of this class is passed to the graph components during drawing.

The AreaGraph Class

AreaGraph(data, **options) (class) [#]

Area plot. This is similar to LineGraph, but fills the region beneath the line.

data: Input data, given as a tuple of two arrays (xdata, ydata).
**options: Plot options.
brush=: Brush object.

The Axes Class

Axes(data=None, **options) (class) [#]

Standard axes handling. This element sets up a drawing extent for subsequent elements, and also draws axes to the left and below the graph area.

data: Graph data. If given, the class calculates the extent from the actual graph values. If not given, the extent is taken from the extent option.
**options: Axes options.
extent=: Graph extent.
grid=: Grid pen. If given, this should be a Pen object.
xaxis=: Where to draw the x-axis. Can be “bottom” or “none”. Default is “bottom”.
yaxis=: Where to draw the y-axis. Can be one of “left”, “right”, “both”, or “none”. Default is “left”.
xoffset=: Distance between the x-axis and the graph canvas. Defaults to 0.
yoffset=: Distance between the y-axis and the graph canvas. Defaults to 0.

getextent() [#]

Gets the current graph extent.

Returns:: The graph extent (xmin, ymin, xmax, ymax).

makeaxis(axis, lo, hi) [#]

(Hook) Calculates min and max values for an individual graph axis, and determines where to draw tick marks.

axis: Axis type (“x” or “y”).
lo: Start of axis.
hi: End of axis.
Returns:: A tuple containing adjusted start and end positions, plus a list of (value, label) tick specifiers.

render(context) [#]

(Internal) Renders axes.

context: Graph drawing context.

setextent(extent) [#]

Sets the graph extent.

extent: The new extent (xmin, ymin, xmax, ymax).

xlabel(x, label) [#]

(Hook) Generates label for the X axis.

x: X value.
label: Suggested label. The default implementation simply returns this label.
Returns:: The new label. To suppress the label, return None or an empty string.

ylabel(y, label) [#]

(Hook) Generates label for the Y axis.

y: Y value.
label: Suggested label. The default implementation simply returns this label.
Returns:: The new label. To suppress the label, return None or an empty string.

The BarGraph Class

BarGraph(data, **options) (class) [#]

Simple bar plot.

data: Input data, given as a tuple of two arrays (xdata, ydata). Both arrays should have the same length.
**options: Plot options.
brush=: Brush object to use when filling the bars. Use Brush(None) to draw hollow bars.
pen=: Pen object to use for the bar border. Use Pen(None) to draw bars without a border.
barwidth=: Relative barwidth. Defaults to 1.0 (100%).

The Brush Class

Brush(color=”yellow”) (class) [#]

Brush object. This class is used to specify fill styles for various drawing operations.

color=: Brush color.

The GraphWidget Class

GraphWidget(master, **options) (class) [#]

Graph widget. To display a graph, add an axis component, and one or more graph components.

master: Parent widget.
**options: Widget options.
background=: Widget background color.
font=: Widget font.
foreground=: Widget text color.
canvasbackground=: Graph canvas background color. Default is same as the widget background.
height=: Widget height (in pixels). Defaults to 600 pixels.
width=: Widget width (in pixels). Defaults to 400 pixels.

add(layer) [#]

Adds a graph component to this widget.

layer: Layer component.

clear() [#]

Removes all layers from widget.

The LineGraph Class

LineGraph(data, **options) (class) [#]

Line plot.

data: Input data, given as a tuple of two arrays (xdata, ydata). Both arrays should have the same length, and the X array should be monotonically increasing (that is, xdata[i] < xdata[i+1] should be true for the entire array).
**options: Plot options.
pen=: Pen object to use when drawing the line. Defaults to a thin black line.
marker=: Marker object. If omitted, markers are not drawn.
interpolation=: Line interpolation method. Can be one of “linear”, “smooth”, “stairs”, “stem” or “step”. Defaults to “linear”.

The Marker Class

Marker(style=”circle”, color=”blue”, border=”black”, size=5) (class) [#]

Marker object. This is used to specify marker styles for various plotting operations.

style=: Marker style. One of “circle”, “diamond”, “plus”, “square”, or “triangle”. Defaults to “circle”.
color=: Marker fill color. Use None to draw just the border.
border=: Marker border color.
size=: Marker size (radius), in pixels. Defaults to 5.

plot(context, xy) [#]

Plot markers on a surface.

context: Rendering context.
xy: Coordinate array.

The Pen Class

Pen(color=”black”, width=1) (class) [#]

Pen object. This class is used to specify pen styles for various drawing operations.

color=: Pen color.
width=: Pen width.

The ScatterGraph Class

ScatterGraph(data, **options) (class) [#]

Scatter (X-Y) plot.

data: Input data, given as a tuple of two arrays (xdata, ydata). Both arrays should have the same length.
**options: Plot options.
marker=: Marker object. This should be an instance of the Marker class. If omitted, a default marker style is used.

The SimpleGraph Class

SimpleGraph(data, **options) (class) [#]

Base class for simple graphs.

data: Input data, given as a tuple of two arrays (xdata, ydata). Both arrays should have the same length.
**options: Plot options.

render(context) [#]

(Hook) Render graph in context. The default implementation maps input coordinates to pixel coordinates, relative to the graph canvas, and then calls the render_xy method.

context: Rendering context.

render_xy(context, xy) [#]

(Hook) Renders graph in context. Same as render, but the coordinates are given in pixel coordinates.

context: Rendering context.
xy: Coordinate array.