Region Metadata

A Region object has both meta and visual attributes that store the metadata of the region. The RegionMeta and RegionVisual classes handle the general metadata and visual attributes, respectively. Both behave like Python dictionaries.

General Metadata

The Region meta attribute stores additional metadata about the region such as labels, tags, comments, name, etc. that are used for non-display tasks. It can also store the spectral dimensions of the region.

The valid keys in the RegionMeta object are:

• label:

  • CRTF, DS9 (text label for a region)

  • Ex: meta[‘label’] = ‘this is a circle’

• tag:

  • DS9 (All regions may have zero or more tags associated with it, which may be used for grouping and searching.)

  • Ex: meta[‘tags’] = [‘{Group 1}’, ‘{Group 2}’]}

• include:

  • CRTF, DS9 (Region inclusion)

  • Possible Values: True, False

  • Ex: meta[‘include’] = True

• frame:

  • CRTF (Frequency/Velocity Axis)

  • Possible values: ‘REST’, ‘LSRK’, ‘LSRD’, ‘BARY’, ‘GEO’, ‘TOPO’, ‘GALACTO’, ‘LGROUP’, ‘CMB’

  • Default: image value

  • Ex: meta[‘frame’] = ‘TOPO’

• range:

  • CRTF (Frequency/Velocity Range)

  • Possible units: GHz, MHz, kHz, km/s, Hz, channel, chan (=channel)

  • Default: image range

  • Format: [min, max]

  • Ex: meta[‘range’] = [-320 * u.m/u.sec, -330 * u.m/u.s]

• veltype:

  • CRTF (Velocity Calculation)

  • Possible values: ‘RADIO’, ‘OPTICAL’, ‘Z’, ‘BETA’, ‘GAMMA’

  • Default: image value

  • Ex: meta[‘veltype’] = ‘RADIO’

• restfreq:

  • CRTF (Rest Frequency)

  • Possible values: Quantity object

  • Default: image value

  • Ex: meta[‘restfreq’] = Quantity(“1.42GHz”)

• corr:

  • CRTF (Correlational Axis)

  • Possible values: ‘I’, ‘Q’, ‘U’, ‘V’, ‘RR’, ‘RL’, ‘LR’, ‘LL’, ‘XX’, ‘XY’, ‘YX’, ‘YY’, ‘RX’, ‘RY’, ‘LX’, ‘LY’, ‘XR’, ‘XL’, ‘YR’, ‘YL’, ‘PP’, ‘PQ’, ‘QP’, ‘QQ’, ‘RCircular’, ‘LCircular’, ‘Linear’, ‘Ptotal’, ‘Plinear’, ‘PFtotal’, ‘PFlinear’, ‘Pangle’

  • Default: all planes present in image

  • Ex: meta[‘corr’] = [‘X’, ‘Y’]

• comment:

  • DS9, CRTF (Comment on the region)

  • Ex: meta[‘comment’] = ‘Any comment for the region’

• line:

  • DS9 (The line region may be rendered with arrows, one at each end. To indicate arrows, use the line property. A ‘1’ indicates an arrow, ‘0’ indicates no arrow.)

  • Ex: meta[‘line’] = [1, 1]

• name

• select

• highlite

• fixed

• edit:

  • DS9 (The Edit property specifies if the user is allowed to edit the region via the GUI.)

  • Ex: meta[‘edit’] = 1

• move:

  • DS9 (The Move property specifies if the user is allowed to move the region via the GUI. )

  • Ex: meta[‘move’] = 1

• rotate:

  • DS9 (The Rotate property specifies if the user is allowed to rotate the region via the GUI. )

  • Ex: meta[‘rotate’] = 1

• delete:

  • DS9 (The Delete property specifies if the user is allowed to delete the region via the GUI. )

  • Ex: meta[‘delete’] = 1

• source

• background

Visual Metadata

The Region visual attribute stores visual properties for the region such as color, font style, font size, line width, line style, etc. The visual attributes are metadata meant to be used to visualize regions, especially used by plotting libraries such as Matplotlib .

The valid keys in the RegionVisual class are:

• color: CRTF, DS9 (Region, symbol and text color)

  • Possible values: any color recognized by Matplotlib, including hex values

  • Default: color=green

  • Ex: visual[‘color’] = ‘blue’

• dash: Render region using dashed lines using current dashlist value.

• font: Name of the font.

• dashlist: Sets dashed line parameters. This does not render the region in dashed lines.

• symsize: Size of the symbol.

• symthick: Thickness of the symbol.

• fontsize: Size of the font.

• fontstyle: Style of the font.

• usetex: Boolean value whether the label uses TeX.

• labelpos: Position of the label.

• labeloff: Label offset.

• linewidth: Width of the line.

• linestyle: Style of the line.

• fill: Boolean value whether the region is filled.

• line: The line region may be rendered with arrows, one at each end. To indicate arrows, use the line property. A ‘1’ indicates an arrow, ‘0’ indicates no arrow.

• symbol/point: CRTF, DS9 (Symbol for which a point region is described)

  • Ex: meta[‘symbol’] = ‘point marker’