# CoordinateHelper¶

class astropy.visualization.wcsaxes.CoordinateHelper(parent_axes=None, parent_map=None, transform=None, coord_index=None, coord_type='scalar', coord_unit=None, coord_wrap=None, frame=None, format_unit=None)[source]

Bases: object

Helper class to control one of the coordinates in the WCSAxes.

Parameters
parent_axesWCSAxes

The axes the coordinate helper belongs to.

parent_mapCoordinatesMap

The CoordinatesMap object this coordinate belongs to.

transformTransform

The transform corresponding to this coordinate system.

coord_indexint

The index of this coordinate in the CoordinatesMap.

coord_type{‘longitude’, ‘latitude’, ‘scalar’}

The type of this coordinate, which is used to determine the wrapping and boundary behavior of coordinates. Longitudes wrap at coord_wrap, latitudes have to be in the range -90 to 90, and scalars are unbounded and do not wrap.

coord_unitUnit

The unit that this coordinate is in given the output of transform.

format_unitUnit, optional

The unit to use to display the coordinates.

coord_wrapfloat

The angle at which the longitude wraps (defaults to 360)

frameBaseFrame

The frame of the WCSAxes.

Attributes Summary

Methods Summary

 display_minor_ticks(self, display_minor_ticks) Display minor ticks for this coordinate. format_coord(self, value[, format]) Given the value of a coordinate, will format it according to the format of the formatter_locator. get_axislabel(self) Get the text for the axis label get_axislabel_visibility_rule(self, rule) Get the rule used to determine when the axis label is drawn. grid(self[, draw_grid, grid_type]) Plot grid lines for this coordinate. set_axislabel(self, text[, minpad]) Set the text and optionally visual properties for the axis label. set_axislabel_position(self, position) Set where axis labels should appear set_axislabel_visibility_rule(self, rule) Set the rule used to determine when the axis label is drawn. set_coord_type(self, coord_type[, coord_wrap]) Set the coordinate type for the axis. set_format_unit(self, unit[, decimal, …]) Set the unit for the major tick labels. set_major_formatter(self, formatter) Set the formatter to use for the major tick labels. set_minor_frequency(self, frequency) Set the frequency of minor ticks per major ticks. set_separator(self, separator) Set the separator to use for the angle major tick labels. set_ticklabel(self[, color, size, pad, …]) Set the visual properties for the tick labels. set_ticklabel_position(self, position) Set where tick labels should appear set_ticklabel_visible(self, visible) Set whether the tick labels are visible or not. set_ticks(self[, values, spacing, number, …]) Set the location and properties of the ticks. set_ticks_position(self, position) Set where ticks should appear set_ticks_visible(self, visible) Set whether ticks are visible or not. tick_params(self[, which]) Method to set the tick and tick label parameters in the same way as the tick_params() method in Matplotlib.

Attributes Documentation

formatter
locator

Methods Documentation

display_minor_ticks(self, display_minor_ticks)[source]

Display minor ticks for this coordinate.

Parameters
display_minor_ticksbool

Whether or not to display minor ticks.

format_coord(self, value, format='auto')[source]

Given the value of a coordinate, will format it according to the format of the formatter_locator.

Parameters
valuefloat

The value to format

format{‘auto’, ‘ascii’, ‘latex’}, optional

The format to use - by default the formatting will be adjusted depending on whether Matplotlib is using LaTeX or MathTex. To get plain ASCII strings, use format=’ascii’.

get_axislabel(self)[source]

Get the text for the axis label

Returns
labelstr

The axis label

get_axislabel_visibility_rule(self, rule)[source]

Get the rule used to determine when the axis label is drawn.

get_minor_frequency(self)[source]
grid(self, draw_grid=True, grid_type=None, **kwargs)[source]

Plot grid lines for this coordinate.

Standard matplotlib appearance options (color, alpha, etc.) can be passed as keyword arguments.

Parameters
draw_gridbool

Whether to show the gridlines

grid_type{‘lines’, ‘contours’}

Whether to plot the contours by determining the grid lines in world coordinates and then plotting them in world coordinates ('lines') or by determining the world coordinates at many positions in the image and then drawing contours ('contours'). The first is recommended for 2-d images, while for 3-d (or higher dimensional) cubes, the 'contours' option is recommended. By default, ‘lines’ is used if the transform has an inverse, otherwise ‘contours’ is used.

set_axislabel(self, text, minpad=1, **kwargs)[source]

Set the text and optionally visual properties for the axis label.

Parameters
textstr

The axis label text.

The padding for the label in terms of axis label font size.

kwargs

Keywords are passed to matplotlib.text.Text. These can include keywords to set the color, size, weight, and other text properties.

set_axislabel_position(self, position)[source]

Set where axis labels should appear

Parameters
positionstr

The axes on which the axis label for this coordinate should appear. Should be a string containing zero or more of 'b', 't', 'l', 'r'. For example, 'lb' will lead the axis label to be shown on the left and bottom axis.

set_axislabel_visibility_rule(self, rule)[source]

Set the rule used to determine when the axis label is drawn.

Parameters
rulestr

If the rule is ‘always’ axis labels will always be drawn on the axis. If the rule is ‘ticks’ the label will only be drawn if ticks were drawn on that axis. If the rule is ‘labels’ the axis label will only be drawn if tick labels were drawn on that axis.

set_coord_type(self, coord_type, coord_wrap=None)[source]

Set the coordinate type for the axis.

Parameters
coord_typestr

One of ‘longitude’, ‘latitude’ or ‘scalar’

coord_wrapfloat, optional

The value to wrap at for angular coordinates

set_format_unit(self, unit, decimal=None, show_decimal_unit=True)[source]

Set the unit for the major tick labels.

Parameters
unitclass:Unit

The unit to which the tick labels should be converted to.

decimalbool, optional

Whether to use decimal formatting. By default this is False for degrees or hours (which therefore use sexagesimal formatting) and True for all other units.

show_decimal_unitbool, optional

Whether to include units when in decimal mode.

set_major_formatter(self, formatter)[source]

Set the formatter to use for the major tick labels.

Parameters
formatterstr or Formatter

The format or formatter to use.

set_minor_frequency(self, frequency)[source]

Set the frequency of minor ticks per major ticks.

Parameters
frequencyint

The number of minor ticks per major ticks.

set_separator(self, separator)[source]

Set the separator to use for the angle major tick labels.

Parameters
separatorstr or tuple or None

The separator between numbers in sexagesimal representation. Can be either a string or a tuple (or None for default).

set_ticklabel(self, color=None, size=None, pad=None, exclude_overlapping=None, **kwargs)[source]

Set the visual properties for the tick labels.

Parameters
sizefloat, optional

The size of the ticks labels in points

colorstr or tuple, optional

A valid Matplotlib color for the tick labels

Distance in points between tick and label.

exclude_overlappingbool, optional

Whether to exclude tick labels that overlap over each other.

kwargs

Other keyword arguments are passed to matplotlib.text.Text.

set_ticklabel_position(self, position)[source]

Set where tick labels should appear

Parameters
positionstr

The axes on which the tick labels for this coordinate should appear. Should be a string containing zero or more of 'b', 't', 'l', 'r'. For example, 'lb' will lead the tick labels to be shown on the left and bottom axis.

set_ticklabel_visible(self, visible)[source]

Set whether the tick labels are visible or not.

Parameters
visiblebool

The visibility of ticks. Setting as False will hide this coordinate’s tick labels.

set_ticks(self, values=None, spacing=None, number=None, size=None, width=None, color=None, alpha=None, direction=None, exclude_overlapping=None)[source]

Set the location and properties of the ticks.

At most one of the options from values, spacing, or number can be specified.

Parameters
valuesiterable, optional

The coordinate values at which to show the ticks.

spacingfloat, optional

The spacing between ticks.

numberfloat, optional

The approximate number of ticks shown.

sizefloat, optional

The length of the ticks in points

colorstr or tuple, optional

A valid Matplotlib color for the ticks

alphafloat, optional

The alpha value (transparency) for the ticks.

direction{‘in’,’out’}, optional

Whether the ticks should point inwards or outwards.

set_ticks_position(self, position)[source]

Set where ticks should appear

Parameters
positionstr

The axes on which the ticks for this coordinate should appear. Should be a string containing zero or more of 'b', 't', 'l', 'r'. For example, 'lb' will lead the ticks to be shown on the left and bottom axis.

set_ticks_visible(self, visible)[source]

Set whether ticks are visible or not.

Parameters
visiblebool

The visibility of ticks. Setting as False will hide ticks along this coordinate.

tick_params(self, which='both', **kwargs)[source]

Method to set the tick and tick label parameters in the same way as the tick_params() method in Matplotlib.

This is provided for convenience, but the recommended API is to use set_ticks(), set_ticklabel(), set_ticks_position(), set_ticklabel_position(), and grid().

Parameters
which{‘both’, ‘major’, ‘minor’}, optional

Which ticks to apply the settings to. By default, setting are applied to both major and minor ticks. Note that if 'minor' is specified, only the length of the ticks can be set currently.

direction{‘in’, ‘out’}, optional

Puts ticks inside the axes, or outside the axes.

lengthfloat, optional

Tick length in points.

widthfloat, optional

Tick width in points.

colorcolor, optional

Tick color (accepts any valid Matplotlib color)

Distance in points between tick and label.

labelsizefloat or str, optional

Tick label font size in points or as a string (e.g., ‘large’).

labelcolorcolor, optional

Tick label color (accepts any valid Matplotlib color)

colorscolor, optional
Changes the tick color and the label color to the same value

(accepts any valid Matplotlib color).

bottom, top, left, rightbool, optional

Where to draw the ticks. Note that this will not work correctly if the frame is not rectangular.

labelbottom, labeltop, labelleft, labelrightbool, optional

Where to draw the tick labels. Note that this will not work correctly if the frame is not rectangular.

grid_colorcolor, optional

The color of the grid lines (accepts any valid Matplotlib color).

grid_alphafloat, optional

Transparency of grid lines: 0 (transparent) to 1 (opaque).

grid_linewidthfloat, optional

Width of grid lines in points.

grid_linestylestring, optional

The style of the grid lines (accepts any valid Matplotlib line style).