astro py:docs

- Index
- Modules

### Navigation

- next »
- « previous |
- Astropy v5.2.1 »
- Astronomical Coordinate Systems (`astropy.coordinates`) »
- CylindricalRepresentation

# CylindricalRepresentation

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

  Bases: `BaseRepresentation`

  Representation of points in 3D cylindrical coordinates.

  Parameters:
    rho `Quantity`

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

    phi `Quantity` or `python: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 `python: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. 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`() | 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)

    Converts 3D rectangular cartesian coordinates to cylindrical polar coordinates.

  scale_factors()

    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 `python:dict` of `Quantity`

        The keys are the component names.

  to_cartesian()

    Converts cylindrical polar coordinates to 3D rectangular cartesian coordinates.

  unit_vectors()

    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 `python:dict` of `CartesianRepresentation`

        The keys are the component names.