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, default_label=None)

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_wrapastropy.units.Quantity

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

frameBaseFrame

The frame of the WCSAxes.

default_labelstr, optional

The axis label to show by default if none is set later.

Attributes Summary

axislabels
coord_index	The index of this coordinate in the CoordinatesMap.
coord_type	The type of this coordinate (e.g., 'longitude')
coord_unit	The unit that this coordinate is in given the output of transform.
coord_wrap	The angle at which the longitude wraps (defaults to 360 degrees).
default_label	The axis label to show by default if none is set later.
formatter
frame	The frame of the WCSAxes.
locator
parent_axes	The axes the coordinate helper belongs to.
parent_map	The CoordinatesMap object this coordinate belongs to.
ticklabels
ticks
transform	The transform corresponding to this coordinate system.

Methods Summary

add_tickable_gridline(name, constant)	Define a gridline that can be used for ticks and labels.
display_minor_ticks(display_minor_ticks)	Display minor ticks for this coordinate.
format_coord(value[, format])	Given the value of a coordinate, will format it according to the format of the formatter_locator.
get_auto_axislabel()	Render default axis labels if no explicit label is provided.
get_axislabel()	Get the text for the axis label.
get_axislabel_position()	Get where axis labels will appear.
get_axislabel_visibility_rule(rule)	Get the rule used to determine when the axis label is drawn.
get_format_unit()	Get the unit for the major tick labels.
get_minor_frequency()
get_ticklabel_position()	Get where tick labels will appear.
get_ticks_position()	Get where tick labels will appear.
grid([draw_grid, grid_type])	Plot grid lines for this coordinate.
set_auto_axislabel(auto_label)	Render default axis labels if no explicit label is provided.
set_axislabel(text[, minpad])	Set the text and optionally visual properties for the axis label.
set_axislabel_position(position)	Set where axis labels should appear.
set_axislabel_visibility_rule(rule)	Set the rule used to determine when the axis label is drawn.
set_coord_type(coord_type[, coord_wrap])	Set the coordinate type for the axis.
set_format_unit(unit[, decimal, ...])	Set the unit for the major tick labels.
set_major_formatter(formatter)	Set the format string to use for the major tick labels.
set_minor_frequency(frequency)	Set the frequency of minor ticks per major ticks.
set_separator(separator)	Set the separator to use for the angle major tick labels.
set_ticklabel([color, size, pad, ...])	Set the visual properties for the tick labels.
set_ticklabel_position(position)	Set where tick labels should appear.
set_ticklabel_visible(visible)	Set whether the tick labels are visible or not.
set_ticks([values, spacing, number, size, ...])	Set the location and properties of the ticks.
set_ticks_position(position)	Set where ticks should appear.
set_ticks_visible(visible)	Set whether ticks are visible or not.
tick_params([which])	Method to set the tick and tick label parameters in the same way as the tick_params() method in Matplotlib.

Attributes Documentation

axislabels

coord_index

The index of this coordinate in the CoordinatesMap.

coord_type

The type of this coordinate (e.g., 'longitude')

coord_unit

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

coord_wrap

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

default_label

The axis label to show by default if none is set later.

formatter

frame

The frame of the WCSAxes.

locator

parent_axes

The axes the coordinate helper belongs to.

parent_map

The CoordinatesMap object this coordinate belongs to.

ticklabels

ticks

transform

The transform corresponding to this coordinate system.

Methods Documentation

add_tickable_gridline(name, constant)

Define a gridline that can be used for ticks and labels.

This gridline is not itself drawn, but instead can be specified in calls to methods such as set_ticklabel_position() for drawing ticks and labels. Since the gridline has a constant value in this coordinate, and thus would not have any ticks or labels for the same coordinate, the call to set_ticklabel_position() would typically be made on the complementary coordinate.

Parameters:

namestr

The name for the gridline, usually a single character, but can be longer

constantQuantity

The constant coordinate value of the gridline

Notes

A limitation is that the tickable part of the gridline must be contiguous. If the gridline consists of more than one disconnected segment within the plot extent, only one of those segments will be made tickable.

display_minor_ticks(display_minor_ticks)

Display minor ticks for this coordinate.

Parameters:

display_minor_ticksbool

Whether or not to display minor ticks.

format_coord(value, format='auto')

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_auto_axislabel()

Render default axis labels if no explicit label is provided.

Returns:

auto_axislabelbool

True if default labels will be rendered.

get_axislabel()

Get the text for the axis label.

Returns:

labelstr

The axis label

get_axislabel_position()

Get where axis labels will appear.

get_axislabel_visibility_rule(rule)

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

get_format_unit()

Get the unit for the major tick labels.

get_minor_frequency()

get_ticklabel_position()

Get where tick labels will appear.

get_ticks_position()

Get where tick labels will appear.

grid(draw_grid=True, grid_type=None, **kwargs)

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_auto_axislabel(auto_label)

Render default axis labels if no explicit label is provided.

Parameters:

auto_labelbool

True if default labels will be rendered.

set_axislabel(text, minpad=1, **kwargs)

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

Parameters:

textstr

The axis label text.

minpadfloat, optional

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(position)

Set where axis labels should appear.

Parameters:

positionstr or list

The axes on which the axis label for this coordinate should appear. Should be a sequence 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. In addition, if '#' is included in the sequence, the position will be considered dynamic and will be updated at draw-time in order to show the axis label on the same axes as the tick labels are shown.

set_axislabel_visibility_rule(rule)

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(coord_type, coord_wrap=None)

Set the coordinate type for the axis.

Parameters:

coord_typestr

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

coord_wrapQuantity, optional

The value to wrap at for angular coordinates.

set_format_unit(unit, decimal=None, show_decimal_unit=True)

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(formatter)

Set the format string to use for the major tick labels.

See Tick label format for accepted format strings and examples.

Parameters:

formatterstr or callable()

The format string to use, or a callable (for advanced use cases). If specified as a callable, this should take a Quantity (which could be scalar or array) of tick world coordinates as well as an optional spacing keyword argument, which gives (also as a Quantity) the spacing between ticks, and returns an iterable of strings containing the labels.

set_minor_frequency(frequency)

Set the frequency of minor ticks per major ticks.

Parameters:

frequencyint

The number of minor ticks per major ticks.

set_separator(separator)

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(color=None, size=None, pad=None, exclude_overlapping=None, *, simplify=True, **kwargs)

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

padfloat, optional

Distance in points between tick and label.

exclude_overlappingbool, optional

Whether to exclude tick labels that overlap over each other.

simplifybool, optional

Whether to remove repeated parts of tick labels.

**kwargs

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

set_ticklabel_position(position)

Set where tick labels should appear.

Parameters:

positionstr or list

The axes on which the tick labels for this coordinate should appear. Should be a sequence 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. In addition, if '#' is included in the sequence, the position will be considered dynamic and will be updated at draw-time in order to attempt to optimize the layout of all the coordinates.

set_ticklabel_visible(visible)

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(values=None, spacing=None, number=None, size=None, width=None, color=None, alpha=None, direction=None, exclude_overlapping=None)

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(position)

Set where ticks should appear.

Parameters:

positionstr or list

The axes on which the ticks for this coordinate should appear. Should be a sequence 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. In addition, if '#' is included in the sequence, the position will be considered dynamic and will be updated at draw-time in order to show the ticks on the same axes as the tick labels are shown.

set_ticks_visible(visible)

Set whether ticks are visible or not.

Parameters:

visiblebool

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

tick_params(which='both', **kwargs)

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)

padfloat, optional

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_linestylestr, optional

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