Diagram () -> Diagram An abstract widget class for diagram and graph implementations. The Diagram class contains the minimum set of attributes and methods needed to visualize diagrams or graphs from arbitrary data. Diagrams can have different resolutions, dependant on the value range, that should be displayed. Inheritors thus have to implement the 'units' attribute and its related methods get_units() and set_units(), which define, how many pixels between each full unit have to be left. Greater values usually result in a higher resolution, resp. pixel amount between the values. To allow the user to know about the kind of data, that is evaluated and displayed, the 'scale_units' attribute and its related methods get_scale_units() and set_scale_units() must be implemented. Those define the concrete type of data, that is displayed on each axis of the diagram (e.g. cm, inch, kg...). The 'axes' attribute and its related methods get_axes() and set_axes(), which have to be implemented. denote the axes, which are used to set the data and its results into relation. A typical cartesian coordinate plane for example will have two axes (x and y). The 'orientation' attribute should be respected by inheritors to allow displaying data in a vertical or horizontal align. diagram.orientation = ORIENTATION_HORIZONTAL diagram.set_orientation (ORIENTATION_VERTICAL) The Diagram contains a 'negative' attribute and set_negative() method, which indicate, whether negative values should be shown or not. diagram.negative = True diagram.set_negative = False The 'origin' attribute and set_origin() method set the point of origin of the diagram on its widget surface and denote a tuple of an x and y value. Inheritors should use this to set the point of origin of their diagram type. Most diagram implementors usually would use this as a relative coordinate to the bottom left corner of the widget surface. Note, that this is different from a real relative position on the widget surface, as those are related to the topleft corner diagram.origin = 10, 10 diagram.set_origin (20, 20) The 'data' attribute and set_data() method set the data to be evaluated by the diagram inheritor using the evaluate() method. It is up to the inheritor to perform additional sanity checks. diagram.data = mydata diagram.set_data (mydata) An evaluation function, which processes the set data can be set using the 'eval_func' attribute or set_eval_func() method. If set, the evaluate() method will process the set data using the eval_func and store the return values in its 'values' attribute. Otherwise, the values will be set to the data. def power_1 (x): return x**2 - x diagram.eval_func = power_1 The evaluate() method of the widget distinguishes between the type of data and will act differently, dependant on whether it is a sequence or not. Lists and tuples will be passed to the eval_func using the python map() function, else the complete data will be passed to the eval_func: # Data is list or tuple: self.values = map (self.eval_func, data) # Any other type of data: self.values = self.eval_func (data) The result values can also be set manually without any processing using the 'values' attribute and set_values() method. This can be useful for inheritors like a bar chart for example. self.values = myvalues self.set_values (myvalues) A concrete implementation of the Diagram class can be found as Graph2D widget within this module. Default action (invoked by activate()): None Mnemonic action (invoked by activate_mnemonic()): None Attributes: scale_units - The scale unit(s) to set for the axes. units - Pixels per unit to set. axes - The axes to show. negative - Indicates, that negative vaues should be taken into account. orientation - The orientation mapping of the axes. origin - The position of the point of origin on the widget. data - Data to evaluate. values - Result values of the set data after evaluation. eval_func - Evaluation function to calculate the values.
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Static Public Attributes