# CylindricalRepresentation¶

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

Representation of points in 3D cylindrical coordinates.

Parameters
rhoQuantity

The distance from the z axis to the point(s).

phi

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,

zQuantity

The z coordinate(s) of the point(s)

differentials

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.

copybool, optional

If True (default), arrays will be copied. If False, arrays will be references, though possibly broadcast to ensure matching shapes.

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 for each component’s direction. Converts cylindrical polar coordinates to 3D rectangular cartesian coordinates. 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]

Converts 3D rectangular cartesian coordinates to cylindrical polar coordinates.

scale_factors()[source]

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

The keys are the component names.

to_cartesian()[source]

Converts cylindrical polar coordinates to 3D rectangular cartesian coordinates.

unit_vectors()[source]

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.