at.load.elegant#

Using Elegant files with PyAT#

PyAT can read lattice descriptions in Elegant format (.lte files), and can export lattices in Elegant format.

However, because of intrinsic differences between PyAT and Elegant, some incompatibilities must be taken into account.

1. Translation losses#

Multipoles#

Elegant thick multipoles are limited to a single multipole order. For AT Multipole elements combining several orders, the lowest order is converted and higher orders are discarded. AT ThinMultipole elements are expanded to a series of thin MULT elements with 0 length.

Elegant elements absent from AT#

Many Elegant elements have no equivalent in AT. They are replaced by Marker or Drift elements, depending on their length.

Incompatible attributes#

Some AT element attributes have no Elegant equivalent, and vice versa.

When exporting to an Elegant file:

FringeBendEntrance, FringeBendExit, FringeQuadEntrance, FringeQuadExit are discarded,
R1, R2, T1, T2 are discarded,
RApertures, EApertures are discarded.

When reading an Elegant file:

TILT is interpreted and converted to R1 and R2 attributes,
DX, DZ are converted to T1`and `T2 attributes,
N_SLICES, if specified, is converted to NumIntSteps. If not, NumIntSteps is left to is default value (10).

2. Usage#

Usage Elegant files is similar to using MAD-X files. The Elegant RPN calculator is emulated.

3. Functions and classes#

Functions

load_elegant(*files[, use, verbose])

Create a Lattice from Elegant lattice files

Classes

ElegantParser(**kwargs)

Elegant parser

class ElegantParser(**kwargs)[source]#

Bases: UpperCaseParser, BaseParser

Elegant parser

The parser is a subclass of dict and is a database containing all the Elegant objects.

Example

Parse a file:

>>> parser = at.ElegantParser()
>>> parser.parse_file("file1")

Look at the “qf1” element

>>> parser["QF1"]
QUAD(name=QF1, l=1.0, k1=0.5, tilt=0.001)

Generate an AT Lattice from the “RING” sequence

>>> ring = parser.lattice(use="RING")  # generate an AT Lattice

Parameters:

verbose – If True, print details on the processing
**kwargs – Initial variable definitions

clear()#: Clear the database: remove all parameters and objects

evaluate(expr)#

Evaluate the right side of an expression

Parameters:: expr (str) – expression to evaluate
Returns:: value – evaluated expression

expand(key)#

iterator over AT objects generated by a source object

lattice(use='ring', **kwargs)#

Create a lattice from the selected sequence

Parameters:

use – Name of the sequence or line containing the desired lattice. Default: ring

Keyword Arguments:

name (str) – Name of the lattice. Default: sequence name.
particle (Particle) – Circulating particle. Default: Particle(“relativistic”)
energy (float) – Energy of the lattice [eV]. Default: 1.0 GeV
periodicity (int) – Number of periods. Default: 1
* – All other keywords will be set as Lattice attributes

parse_files(*filenames, final=True, prolog=None, epilog=None, **kwargs)#

Process files and fill the database

Parameters:

*filenames (str) – Files to process
final (bool) – If True, signals that the undefined variables may be set to the default value
prolog (None | int | Callable[[...], None])
epilog (Callable[[...], None] | None)
**kwargs – Initial variable definitions

parse_lines(lines, *, final=True, **kwargs)#

Process input lines and fill the database

Parameters:

lines (Iterable[str]) – Iterable of input lines
final (bool) – If True, signals that the undefined variables may be set to the default value
**kwargs – Initial variable definitions

property ignored#: Set of ignored commands

property missing#: Set of missing definitions

property sequences#: List of available sequences or lines

load_elegant(*files, use='RING', verbose=False, **kwargs)[source]#

Create a Lattice from Elegant lattice files

Elegant lattice files do not specify the beam energy. ElegantParser sets it by default to 1.0 GeV. Use the energy keyword to set it to the desired value.
Long elements are split according to the default AT value of NumIntSteps (10) unless N_SLICES is specified in the Elegant element definition.

Parameters:

files (str) – Names of one or several Elegant lattice description files
use (str) – Name of the Elegant LINE describing the desired lattice. Default: RING
verbose (bool) – If True, print details on the processing

Keyword Arguments:

name (str) – Name of the lattice. Default: Elegant sequence name
particle (Particle) – Circulating particle. Default: Particle(“relativistic”)
energy (float) – Energy of the lattice [eV]. Default: 1.0E9
periodicity (int) – Number of periods. Default: 1
* – Other keywords will be used as Lattice attributes

Returns:

lattice (Lattice) – New Lattice object