# CylindricalRepresentation¶

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

Representation of points in 3D cylindrical coordinates.

Parameters
rhoQuantity

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

phiQuantity 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,

zQuantity

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

differentialsdict, 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.

copybool, 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(self) Scale factors for each component’s direction. to_cartesian(self) Converts cylindrical polar coordinates to 3D rectangular cartesian coordinates. unit_vectors(self) 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(self)[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_factorsdict of Quantity

The keys are the component names.

to_cartesian(self)[source]

Converts cylindrical polar coordinates to 3D rectangular cartesian coordinates.

unit_vectors(self)[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.