BaseBackend

class sherpa.plot.backends.BaseBackend

Bases: object

A dummy backend for plotting.

This backend implements only minimal functionality (some formatting of strings as HTML or LaTeX which are usually used as axis labels), but no real plotting capabilities. It is here to ensure that the sherpa.plot module can be imported, even if no plotting backend is installed.

In this sense, this backend can be understood as the “base” for backends. The string-formatting is implemented here so that other backends don’t have to duplicate that; they can call the functions here.

No plotting is implemented in this backend, but all functions are documented by what they should do, so that this backend can serve as a template to implement actual plotting interfaces.

Attributes Summary

name	An easy-to-read string name
translate_dict	Dict of keyword arguments that need to be translated for this backend.

Methods Summary

as_html(data, fields)	Create HTML representation of a plot
as_html_cdf(plot)
as_html_contour1d(plot)
as_html_contour2d(plot)
as_html_data(plot)
as_html_datacontour(plot)
as_html_fit(plot)
as_html_fitcontour(plot)
as_html_histogram(plot)
as_html_lr(plot)
as_html_model(plot)
as_html_modelcontour(plot)
as_html_pdf(plot)
clear_window()	Provide empty plot window
colorlist(n)	Generate the list of n colors for use in multi-line plots.
contour(x0, x1, y, *[, levels, title, ...])	Draw 2D contour data.
get_cdf_plot_defaults()
get_component_histo_defaults()
get_component_plot_defaults()
get_confid_contour_defaults()
get_confid_plot_defaults()
get_confid_point_defaults()
get_contour_defaults()
get_data_contour_defaults()
get_data_plot_defaults()
get_fit_contour_defaults()
get_fit_plot_defaults()
get_histo_defaults()
get_html(attr)
get_image_defaults()	Currently, there are no configurable settings
get_latex_for_string(txt)	Convert LaTeX formula
get_model_contour_defaults()
get_model_histo_defaults()
get_model_plot_defaults()
get_plot_defaults()
get_point_defaults()
get_ratio_contour_defaults()
get_ratio_plot_defaults()
get_resid_contour_defaults()
get_resid_histo_defaults()
get_resid_plot_defaults()
get_rmf_plot_defaults()
get_scatter_plot_defaults()
get_split_plot_defaults()
histo(xlo, xhi, y, *[, yerr, title, xlabel, ...])	Draw histogram data.
hline(y, *[, xmin, xmax, title, xlabel, ...])	Draw a horizontal line
image(x0, x1, y, *[, aspect, title, xlabel, ...])	Draw 2D image data.
initialize_plot(dataset, ids)	Create the plot window or figure for the given dataset.
plot(x, y, *[, xerr, yerr, title, xlabel, ...])	Draw x, y data.
select_plot(dataset, ids)	Select the plot window or figure for the given dataset.
set_jointplot(row, col, nrows, ncols[, ...])	Move to the plot, creating them if necessary.
set_subplot(row, col, nrows, ncols[, clearaxes])	Select a plot space in a grid of plots or create new grid
set_title(title)	Change the display title.
vline(x, *[, ymin, ymax, title, xlabel, ...])	Draw a vertical line

Attributes Documentation

name

An easy-to-read string name

translate_dict = {}

Dict of keyword arguments that need to be translated for this backend.

The keys in this dict are keyword arguments (e.g. 'markerfacecolor') and the values are one of the following:

• A dict where the keys are the backend-independent values and the values are the values expressed for this backend. For values not listed in the dict, no translation is done.

• A callable. The callable translation function is called with any argument given and allows the backend arbitrary translations. It should, at the very least, accept all backend independent values for this parameter without error.

Example:

>>> translate_dict = {'markerfacecolor': {'k': (0., 0., 0.)},
...                   'alpha': lambda a: 255 * a}

This translates the color ‘k’ to tuple of RGB values and alpha values to a number between 0 and 255.

Methods Documentation

as_html(data, fields)

Create HTML representation of a plot

Parameters:

• data (Plot instance) – The plot object to display.

• fields (sequence of strings) – The fields of data to use.

as_html_cdf(plot)

as_html_contour1d(plot)

as_html_contour2d(plot)

as_html_data(plot)

as_html_datacontour(plot)

as_html_fit(plot)

as_html_fitcontour(plot)

as_html_histogram(plot)

as_html_lr(plot)

as_html_model(plot)

as_html_modelcontour(plot)

as_html_pdf(plot)

clear_window()

Provide empty plot window

Depending on the backend, this may provide a new, empty window or clear the existing, current window.

colorlist(n)

Generate the list of n colors for use in multi-line plots.

Generally, the color will be ordered in some way and do not repeat or do so only after a large number of colors. Different backends might generate different lists of colors.

Parameters:

n (int) – Number of colors requested

Returns:

colors – list of color specifiers

Return type:

list

contour(x0, x1, y, *, levels=None, title=None, xlabel=None, ylabel=None, overcontour=False, clearwindow=True, xlog=False, ylog=False, label=None, colors=None, linestyles='solid', linewidths=None, alpha=None, **kwargs)

Draw 2D contour data.

Warning

This backend is a non-functional dummy. The documentation is provided as a template only.

Parameters:

• x0 (array-like) – independent axis in the first dimenation (on regular grid, flattened)

• x1 (array-like) – independent axis in the second dimenation (on regular grid, flattened)

• y (array-like) – dependent axis (i.e. image values) (on regular grid, flattened)

• levels (array-like, default=None) – Levels at which to draw the contours

• title (str, default=None) – Plot title (can contain LaTeX formulas). Only used if a new plot is created.

• xlabel (str, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• ylabel (string, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• overcontour (, default=False)

• clearwindow (bool, default=True) – If True the entire figure area is cleared to make space for a new plot.

• xlog (bool, default=False) – Should the x axis be logarithmic (default: linear)? Only used if a new plot is created.

• ylog (bool, default=False) – Should the y axis be logarithmic (default: linear)? Only used if a new plot is created.

• label (str, default=None) – Label this dataset for use in a legend

• colors (, default=None)

• linestyles (, default=solid)

• linewidths (, default=None)

• alpha (float, default=None) – Number between 0 and 1, setting the transparency.

• kwargs (dict, optional) – All other keyword parameters are passed to the plotting library.

get_cdf_plot_defaults()

get_component_histo_defaults()

get_component_plot_defaults()

get_confid_contour_defaults()

get_confid_plot_defaults()

get_confid_point_defaults()

get_contour_defaults()

get_data_contour_defaults()

get_data_plot_defaults()

get_fit_contour_defaults()

get_fit_plot_defaults()

get_histo_defaults()

get_html(attr)

get_image_defaults()

Currently, there are no configurable settings

get_latex_for_string(txt)

Convert LaTeX formula

Parameters:

txt (str) – The text component in LaTeX form (e.g. r’lpha^2’). It should not contain any non-LaTeX content.

Returns:

latex – The text modified as appropriate for a backend so that the LaTeX will be displayed properly.

Return type:

str

get_model_contour_defaults()

get_model_histo_defaults()

get_model_plot_defaults()

get_plot_defaults()

get_point_defaults()

get_ratio_contour_defaults()

get_ratio_plot_defaults()

get_resid_contour_defaults()

get_resid_histo_defaults()

get_resid_plot_defaults()

get_rmf_plot_defaults()

get_scatter_plot_defaults()

get_split_plot_defaults()

histo(xlo, xhi, y, *, yerr=None, title=None, xlabel=None, ylabel=None, overplot=False, clearwindow=True, xlog=False, ylog=False, label=None, xerrorbars=False, yerrorbars=False, color=None, linestyle='solid', linewidth=None, marker='None', alpha=None, markerfacecolor=None, markersize=None, ecolor=None, capsize=None, **kwargs)

Draw histogram data.

The histogram is drawn as horizontal lines connecting the start and end points of each bin, with vertical lines connecting consecutive bins. Non-consecutive bins are drawn with a (NaN, NaN) between them so no line is drawn connecting them.

Points are drawn at the middle of the bin, along with any error values.

Warning

This backend is a non-functional dummy. The documentation is provided as a template only.

Parameters:

• x0 (array-like or scalar number) – lower bin boundary values

• x1 (array-like or scalar number) – upper bin boundary values

• y (array-like or scalar number) – y values, same dimension as x0.

• yerr (float or array-like, shape(N,) or shape(2, N), default=None) –

  The errorbar sizes can be:

  • scalar: Symmetric +/- values for all data points.

  • shape(N,): Symmetric +/-values for each data point.

  • shape(2, N): Separate - and + values for each bar. First row contains the lower errors, the second row contains the upper errors.

  • None: No errorbar.

  Note that all error arrays should have positive values.

• title (str, default=None) – Plot title (can contain LaTeX formulas). Only used if a new plot is created.

• xlabel (str, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• ylabel (string, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• overplot (bool, default=False) – If True, the plot is added to an existing plot, if not a new plot is created.

• clearwindow (bool, default=True) – If True the entire figure area is cleared to make space for a new plot.

• xlog (bool, default=False) – Should the x axis be logarithmic (default: linear)? Only used if a new plot is created.

• ylog (bool, default=False) – Should the y axis be logarithmic (default: linear)? Only used if a new plot is created.

• label (str, default=None) – Label this dataset for use in a legend

• xerrorbars (bool, default=False) – Should x error bars be shown? If this is set to True errorbars are shown, but only if the size of the errorbars is provided in the xerr parameters. The purpose of having a separate switch xerrorbars is that the prepare method of a plot can create the errors and pass them to this method, but the user can still decide to change the style of the plot and choose if error bars should be displayed.

• yerrorbars (bool, default=False) – Should y error bars be shown? If this is set to True errorbars are shown, but only if the size of the errorbars is provided in the yerr parameters. The purpose of having a separate switch yerrorbars is that the prepare method of a plot can create the errors and pass them to this method, but the user can still decide to change the style of the plot and choose if error bars should be displayed.

• color (str, default=None) – The following colors are accepted by all backends: 'b' (blue), 'r' (red), 'g' (green), 'k' (black), 'w' (white), 'c' (cyan), 'y' (yellow), 'm' (magenta) but they may not translate to the exact same RGB values in each backend, e.g. 'b' could be a different shade of blue depending on the backend. Some backends might accept additional values.

• linestyle (str, default=solid) – The following values are accepted by all backends: 'noline', 'None' (as string, same as 'noline'), 'solid', 'dot', 'dash', 'dashdot', '-' (solid line), ':' (dotted), '--' (dashed), '-.' (dot-dashed), '' (empty string, no line shown), None (default - usually solid line). Some backends may accept additional values.

• linewidth (float, default=None) – Thickness of the line.

• marker (str, default=None) –

  The following values are accepted by all backends: “None” (as a string, no marker shown), “.” (dot), “o” (circle), “+”, “s” (square), “” (empty string, no marker shown), None (no marker shown).

  Some backends may accept additional values.

• alpha (float, default=None) – Number between 0 and 1, setting the transparency.

• markerfacecolor (string, default=None) – see color

• markersize (float, default=None) – Size of a marker. The scale may also depend on the backend. None uses the backend-specific default.

• ecolor (str, default=None) – Color of the error bars.

• capsize (float, default=None) – Size of the cap drawn at the end of the error bars.

• kwargs (dict, optional) – All other keyword parameters are passed to the plotting library.

hline(y, *, xmin=0, xmax=1, title=None, xlabel=None, ylabel=None, overplot=False, clearwindow=True, linecolor=None, linestyle=None, linewidth=None, **kwargs)

Draw a horizontal line

Warning

This backend is a non-functional dummy. The documentation is provided as a template only.

Parameters:

• y (float) – x position of the vertical line in data units

• xmin (float, default=0) – Beginning of the horizontal line in axes coordinates, i.e. from 0 (left) to 1 (right).

• xmax (float, default=1) – End of the vertical line in axes coordinates, i.e. from 0 (left) to 1 (right).

• title (str, default=None) – Plot title (can contain LaTeX formulas). Only used if a new plot is created.

• xlabel (str, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• ylabel (string, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• overplot (bool, default=False) – If True, the plot is added to an existing plot, if not a new plot is created.

• clearwindow (bool, default=True) – If True the entire figure area is cleared to make space for a new plot.

• linecolor (str, default=None) – The following colors are accepted by all backends: 'b' (blue), 'r' (red), 'g' (green), 'k' (black), 'w' (white), 'c' (cyan), 'y' (yellow), 'm' (magenta) but they may not translate to the exact same RGB values in each backend, e.g. 'b' could be a different shade of blue depending on the backend. Some backend might accept additional values.

• linestyle (str, default=None) – The following values are accepted by all backends: 'noline', 'None' (as string, same as 'noline'), 'solid', 'dot', 'dash', 'dashdot', '-' (solid line), ':' (dotted), '--' (dashed), '-.' (dot-dashed), '' (empty string, no line shown), None (default - usually solid line). Some backends may accept additional values.

• linewidth (float, default=None) – Thickness of the line.

• kwargs (dict, optional) – All other keyword parameters are passed to the plotting library.

image(x0, x1, y, *, aspect=1, title=None, xlabel=None, ylabel=None, clearwindow=True, **kwargs)

Draw 2D image data.

Warning

This function is a non-functional dummy. The documentation is provided as a template only.

Parameters:

• x0 (array-like) – independent axis in the first dimenation

• x1 (array-like) – independent axis in the second dimenation

• y (array-like, with shape (len(x0), len(x1))) – dependent axis (i.e. image values) in 2D with shape (len(x0), len(x1))

• aspect (str or float, default=1) – Aspect ratio of the plot. Strings “equal” or “auto” are accepted.

• title (str, default=None) – Plot title (can contain LaTeX formulas). Only used if a new plot is created.

• xlabel (str, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• ylabel (string, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• clearwindow (bool, default=True) – If True the entire figure area is cleared to make space for a new plot.

• kwargs (dict, optional) – All other keyword parameters are passed to the plotting library.

initialize_plot(dataset, ids)

Create the plot window or figure for the given dataset.

Warning

This function is a non-functional dummy. The documentation is provided as a template only.

Parameters:

• dataset (str or int) – The dataset.

• ids (array_like) – The identifier array from the DataStack object.

See also

select_plot

plot(x, y, *, xerr=None, yerr=None, title=None, xlabel=None, ylabel=None, xlog=False, ylog=False, overplot=False, clearwindow=True, label=None, xerrorbars=False, yerrorbars=False, color=None, linestyle='solid', linewidth=None, marker='None', alpha=None, markerfacecolor=None, markersize=None, **kwargs)

Draw x, y data.

This method combines a number of different ways to draw x/y data:

• a line connecting the points

• scatter plot of symbols

• errorbars

All three of them can be used together (symbols with errorbars connected by a line), but it is also possible to use only one or two of them. By default, a line is shown (linestyle='solid'), but marker and error bars are not (marker='None' and xerrorbars=False as well as yerrorbars=False).

Warning

This backend is a non-functional dummy. The documentation is provided as a template only.

Changed in version 4.16.1: The xerr setting now matches the yerr setting and represents the distance from the center to the edge, rather than twice this value.

Parameters:

• x (array-like or scalar number) – x values

• y (array-like or scalar number) – y values, same dimension as x.

• xerr (float or array-like, shape(N,) or shape(2, N), default=None) –

  The errorbar sizes can be:

  • scalar: Symmetric +/- values for all data points.

  • shape(N,): Symmetric +/-values for each data point.

  • shape(2, N): Separate - and + values for each bar. First row contains the lower errors, the second row contains the upper errors.

  • None: No errorbar.

  Note that all error arrays should have positive values.

• yerr (float or array-like, shape(N,) or shape(2, N), default=None) –

  The errorbar sizes can be:

  • scalar: Symmetric +/- values for all data points.

  • shape(N,): Symmetric +/-values for each data point.

  • shape(2, N): Separate - and + values for each bar. First row contains the lower errors, the second row contains the upper errors.

  • None: No errorbar.

  Note that all error arrays should have positive values.

• title (str, default=None) – Plot title (can contain LaTeX formulas). Only used if a new plot is created.

• xlabel (str, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• ylabel (string, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• xlog (bool, default=False) – Should the x axis be logarithmic (default: linear)? Only used if a new plot is created.

• ylog (bool, default=False) – Should the y axis be logarithmic (default: linear)? Only used if a new plot is created.

• overplot (bool, default=False) – If True, the plot is added to an existing plot, if not a new plot is created.

• clearwindow (bool, default=True) – If True the entire figure area is cleared to make space for a new plot.

• label (str, default=None) – Label this dataset for use in a legend

• xerrorbars (bool, default=False) – Should x error bars be shown? If this is set to True errorbars are shown, but only if the size of the errorbars is provided in the xerr parameters. The purpose of having a separate switch xerrorbars is that the prepare method of a plot can create the errors and pass them to this method, but the user can still decide to change the style of the plot and choose if error bars should be displayed.

• yerrorbars (bool, default=False) – Should y error bars be shown? If this is set to True errorbars are shown, but only if the size of the errorbars is provided in the yerr parameters. The purpose of having a separate switch yerrorbars is that the prepare method of a plot can create the errors and pass them to this method, but the user can still decide to change the style of the plot and choose if error bars should be displayed.

• color (str, default=None) – The following colors are accepted by all backends: 'b' (blue), 'r' (red), 'g' (green), 'k' (black), 'w' (white), 'c' (cyan), 'y' (yellow), 'm' (magenta) but they may not translate to the exact same RGB values in each backend, e.g. 'b' could be a different shade of blue depending on the backend. Some backends might accept additional values.

• linestyle (str, default=solid) – The following values are accepted by all backends: 'noline', 'None' (as string, same as 'noline'), 'solid', 'dot', 'dash', 'dashdot', '-' (solid line), ':' (dotted), '--' (dashed), '-.' (dot-dashed), '' (empty string, no line shown), None (default - usually solid line). Some backends may accept additional values.

• linewidth (float, default=None) – Thickness of the line.

• marker (str, default=None) –

  The following values are accepted by all backends: “None” (as a string, no marker shown), “.” (dot), “o” (circle), “+”, “s” (square), “” (empty string, no marker shown), None (no marker shown).

  Some backends may accept additional values.

• alpha (float, default=None) – Number between 0 and 1, setting the transparency.

• markerfacecolor (string, default=None) – see color

• markersize (float, default=None) – Size of a marker. The scale may also depend on the backend. None uses the backend-specific default.

• kwargs (dict, optional) – All other keyword parameters are passed to the plotting library.

select_plot(dataset, ids)

Select the plot window or figure for the given dataset.

The plot for this dataset is assumed to have been created.

Warning

This function is a non-functional dummy. The documentation is provided as a template only.

Parameters:

• dataset (str or int) – The dataset.

• ids (array_like) – The identifier array from the DataStack object.

See also

initialize_plot

set_jointplot(row, col, nrows, ncols, create=True, top=0, ratio=2)

Move to the plot, creating them if necessary.

Warning

This backend is a non-functional dummy. The documentation is provided as a template only.

Parameters:

• row (int) – The row number, starting from 0.

• col (int) – The column number, starting from 0.

• nrows (int) – The number of rows.

• ncols (int) – The number of columns.

• create (bool, optional) – If True then create the plots

• top (int) – The row that is set to the ratio height, numbered from 0.

• ratio (float) – The ratio of the height of row number top to the other rows.

set_subplot(row, col, nrows, ncols, clearaxes=True, **kwargs)

Select a plot space in a grid of plots or create new grid

This method adds a new subplot in a grid of plots.

Warning

This backend is a non-functional dummy. The documentation is provided as a template only.

Parameters:

• row (int) – index (starting at 0) of a subplot in a grid of plots

• col (int) – index (starting at 0) of a subplot in a grid of plots

• nrows (int) – Number of rows and column in the plot grid

• ncols (int) – Number of rows and column in the plot grid

• clearaxes (bool) – If True, clear entire plotting area before adding the new subplot.

Note

This method is intended for grids of plots with the same number of plots in each row and each column. In some backends, more complex layouts (e.g. one wide plot on row 1 and two smaller plots in row 2) might be possible.

set_title(title: str) → None

Change the display title.

Parameters:

title (str) – The title text to use.

vline(x, *, ymin=0, ymax=1, title=None, xlabel=None, ylabel=None, overplot=False, clearwindow=True, linecolor=None, linestyle=None, linewidth=None, **kwargs)

Draw a vertical line

Warning

This backend is a non-functional dummy. The documentation is provided as a template only.

Parameters:

• x (float) – x position of the vertical line in data units

• ymin (float, default=0) – Beginning of the vertical line in axes coordinates, i.e. from 0 (bottom) to 1 (top).

• ymax (float, default=1) – End of the vertical line in axes coordinates, i.e. from 0 (bottom) to 1 (top).

• title (str, default=None) – Plot title (can contain LaTeX formulas). Only used if a new plot is created.

• xlabel (str, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• ylabel (string, default=None) – Axis label (can contain LaTeX formulas). Only used if a new plot is created.

• overplot (bool, default=False) – If True, the plot is added to an existing plot, if not a new plot is created.

• clearwindow (bool, default=True) – If True the entire figure area is cleared to make space for a new plot.

• linecolor (str, default=None) – The following colors are accepted by all backends: 'b' (blue), 'r' (red), 'g' (green), 'k' (black), 'w' (white), 'c' (cyan), 'y' (yellow), 'm' (magenta) but they may not translate to the exact same RGB values in each backend, e.g. 'b' could be a different shade of blue depending on the backend. Some backend might accept additional values.

• linestyle (str, default=None) – The following values are accepted by all backends: 'noline', 'None' (as string, same as 'noline'), 'solid', 'dot', 'dash', 'dashdot', '-' (solid line), ':' (dotted), '--' (dashed), '-.' (dot-dashed), '' (empty string, no line shown), None (default - usually solid line). Some backends may accept additional values.

• linewidth (float, default=None) – Thickness of the line.

• kwargs (dict, optional) – All other keyword parameters are passed to the plotting library.