# CylindricalRepresentation¶

class astropy.coordinates.CylindricalRepresentation(rho, phi, z, differentials=None, copy=True)[source] [edit on github]

Representation of points in 3D cylindrical coordinates.

Parameters: rho : Quantity The distance from the z axis to the point(s). phi : Quantity or str The azimuth of the point(s), in angular units, which will be wrapped to an angle between 0 and 360 degrees. This can also be instances of Angle, z : Quantity The z coordinate(s) of the point(s) differentials : dict, CylindricalDifferential, optional Any differential classes that should be associated with this representation. The input must either be a single CylindricalDifferential instance, or a dictionary of of differential instances with keys set to a string representation of the SI unit with which the differential (derivative) is taken. For example, for a velocity differential on a positional representation, the key would be 's' for seconds, indicating that the derivative is a time derivative. copy : bool, optional If True (default), arrays will be copied rather than referenced.

Attributes Summary

 attr_classes phi The azimuth of the point(s). rho The distance of the point(s) from the z-axis. z The height of the point(s).

Methods Summary

 from_cartesian(cart) Converts 3D rectangular cartesian coordinates to cylindrical polar coordinates. scale_factors() Scale factors for each component’s direction. to_cartesian() Converts cylindrical polar coordinates to 3D rectangular cartesian coordinates. unit_vectors() Cartesian unit vectors in the direction of each component.

Attributes Documentation

attr_classes = {'phi': <class 'astropy.coordinates.angles.Angle'>, 'rho': <class 'astropy.units.quantity.Quantity'>, 'z': <class 'astropy.units.quantity.Quantity'>}
phi

The azimuth of the point(s).

rho

The distance of the point(s) from the z-axis.

z

The height of the point(s).

Methods Documentation

classmethod from_cartesian(cart)[source] [edit on github]

Converts 3D rectangular cartesian coordinates to cylindrical polar coordinates.

scale_factors()[source] [edit on github]

Scale factors for each component’s direction.

Given unit vectors $$\hat{e}_c$$ and scale factors $$f_c$$, a change in one component of $$\delta c$$ corresponds to a change in representation of $$\delta c \times f_c \times \hat{e}_c$$.

Returns: scale_factors : dict of Quantity The keys are the component names.
to_cartesian()[source] [edit on github]

Converts cylindrical polar coordinates to 3D rectangular cartesian coordinates.

unit_vectors()[source] [edit on github]

Cartesian unit vectors in the direction of each component.

Given unit vectors $$\hat{e}_c$$ and scale factors $$f_c$$, a change in one component of $$\delta c$$ corresponds to a change in representation of $$\delta c \times f_c \times \hat{e}_c$$.

Returns: unit_vectors : The keys are the component names.