Module: position

Module: position goniometer/position.py

Goniometer positions, calculations and conversions.

Positions are normally constructed by the Position() factory function from this module. None of the other classes and routines available in this module are widely used outside this implementation.

The Position() objects constructed by the Position() factory can be:

converted to another type using as_?() functions where ? is a one-letter uppercase abbreviation of the type.
modified using the With() method.
queried using attribute references.

Functions

GZero
Null
Position
PositionFromStorage
Zero
angleinrange
fromDatabase
movetorange
normalangle
rangeastype

sameangle
sign

GZero

GZero ( hardware=None )

Return a zero position in g type.

Null

Null ( hardware )

Return zero position.

Position

Position (
        p=None,
        type=None,
        **kw,
        )

Position factory function.

parameters:

type: k for kappa type, e for Euler, f for horizonal Euler, n for euler with counter-clock-wise motors except phi, g for goniometermatrix, b for bisecting, c for C-vector, x for X8 kappa, t for theta1-theta2. d for horizontal euler like in MAR DTB
hardware: hardware used for checking possibilities and for calculations using kappa support angle and wavelength. This can be omitted, but this makes it very difficult to perform conversions.

optional (type specific) parameters:

if type='k': omega, kappa, dx, phi, theta
if type='e': omega, chi, dx, phi, theta
if type='f': omega, chi, dx, phi, theta
if type='d': omega, chi, dx, phi, theta
if type='n': omega, chi, dx, phi, theta
if type='b': dx, theta, phi, chi, psi
if type='c': dx, c, psi, signtheta
if type='g': dx, theta, matrix
if type='x': omega, kappa, dx, phi, theta
if type='t': theta1, theta2, dx

matrix= 3x3-matrix, c= 3-vector, dx in mm, angles in radians.

Alternatively, a position object p can be passed, and a copy will be returned.

Exceptions
Exceptions	TypeError( "unknown type specified in Position()" )

PositionFromStorage

PositionFromStorage ( hardware,  state )

Return the position expressed by the dictionary `state`.

state is a dictionary created using position.storable() before.

Exceptions
Exceptions	error( "Illegal type from storage. Saved in newer version?" )

Zero

Zero ( hardware=None )

Return a zero-position in Kappa angles.

angleinrange

angleinrange (
        a,
        amin,
        amax,
        crit=0.001 * projtls.degrees,
        )

Return true if amin <= a <= amax is fulfilled Within crit.

fromDatabase

fromDatabase ( hardware,  dbobj )

Read position from database.

movetorange

movetorange (
        a,
        amin,
        amax,
        )

Bring angle a between amin and amax. Raise a ValueError exception if that is not possible.

Exceptions
Exceptions	ValueError( 'angle cannot be moved into range' )

normalangle

normalangle ( a )

Bring angle a between -pi and +pi.

rangeastype

rangeastype (
        p1,
        p2,
        type,
        crit=0.001 * projtls.degrees,
        )

Convert positions p1 and p2 to type, keeping differences in axes angles.

Exceptions
Exceptions	TypeError( 'need position objects of same type' )

sameangle

sameangle (
        a1,
        a2,
        crit=0.003 * projtls.degrees,
        )

Return true if a1 and a2 are the same within crit.

sign

sign ( a )

Return -1.0 for negative numbers, 1.0 otherwise.

Classes

PositionBase	Base class for all position types.
error	Exception raised when a conversion can not be performed.

Table of Contents

This document was automatically generated on Tue Nov 25 12:18:58 2008 by HappyDoc version WORKING

Goniometer positions, calculations and conversions.

Position factory function.

Return the position expressed by the dictionary state.

Return the position expressed by the dictionary `state`.