Astropy Glossary

(n,)

A parenthesized number followed by a comma denotes a tuple with one element. The trailing comma distinguishes a one-element tuple from a parenthesized n. This is from NumPy; see https://numpy.org/doc/stable/glossary.html#term-n.

-like

<Class>-like is an instance of the Class or a valid initializer argument for Class as Class(value). E.g. Quantity-like includes "2 * u.km" because astropy.units.Quantity("2 * u.km") works.

[‘physical type’]

The physical type of a quantity can be annotated in square brackets following a Quantity (or similar quantity-like).

For example, distance : quantity-like ['length']

angle-like

quantity-like and a valid initializer for Angle. The unit must be an angular. A string input is interpreted as an angle as described in the Angle documentation.

buffer-like

Object that implements Python’s buffer protocol.

coordinate-like

BaseCoordinateFrame subclass instance, or a SkyCoord (or subclass) instance, or a valid initializer as described in COORD.

file-like (readable)

python:file-like object object that supports reading with a method read.

For a formal definition see ReadableFileLike.

file-like (writeable)

python:file-like object object that supports writing with a method write.

For a formal definition see WriteableFileLike.

frame-like

BaseCoordinateFrame subclass or subclass instance or a valid Frame name (string).

length-like

quantity-like and a valid initializer for Distance. The unit must be a convertible to a unit of length.

number

Any scalar numeric type. e.g. float or int or numpy.number.

quantity-like

Quantity (or subclass) instance, a number or array-like object, or a string which is a valid initializer for Quantity.

For a formal definition see QuantityLike.

table-like

Table (or subclass) instance or valid initializer for Table as described in Constructing a Table. Common types include dict[list], list[dict], list[list], and ndarray (structured array).

time-like

Time (or subclass) instance or a valid initializer for Time, e.g. str, array-like[str], datetime, or datetime64.

unit-like

UnitBase subclass instance or a string or other valid initializer for Unit.

Optional Packages’ Glossary

color

Any valid Matplotlib color.