Getting Started

Which Python?

We require at least Python 3.6 and strongly recommended that you don’t use the system Python installation. The examples in this documentation uses conda since it provides good support also for non Python packages but there are also other alternatives like, pyenv.

Using something like conda also allows you to quickly switch beteen different Python environments.

Building from Source

If you are not installing slsdet binaries from conda, but instead building from source, please refer to the installation section for details.

Don’t forget to compile with the option SLS_USE_PYTHON=ON to enable the Python bindings or if you use the cmk.sh script -p.

Note

Ensure that the sls det python lib compiled is for the expected python version. For example, build/bin/_slsdet.cpython-39-x86_64-linux-gnu.so for Python v3.9.x

PYTHONPATH

If you install slsdet binaries using conda everything is set up and you can directly start using the Python bindings. However, if you build from source you need to tell Python where to find slsdet to use it. This can be done by adding your build/bin directory to PYTHONPATH.

export PYTHONPATH = /path/to/your/build/bin:$PYTHONPATH

Which detector class should I use?

We provide a generic class called Detector and detector specific versions like, Eiger, Jungfrau etc. The most or all functionality is there in the base class except the convenient access to dacs and temperatures.

from slsdet import Detector, Eiger

d = Detector()
e = Eiger()

# Both classes can be used to control an Eiger detector
d.exptime = 0.5
e.period = 1

# But Eiger gives a simpler interface to the dacs
>>> e.dacs
========== DACS =========
vsvp           :    0
vtrim          : 2480
vrpreamp       : 3300
vrshaper       : 1400
vsvn           : 4000
vtgstv         : 2556
vcmp_ll        : 1000
vcmp_lr        : 1000
vcal           :    0
vcmp_rl        : 1000
rxb_rb         : 1100
rxb_lb         : 1100
vcmp_rr        : 1000
vcp            : 1000
vcn            : 2000
vishaper       : 1550
iodelay        :  650

Note

Depending on user feedback we might move some detector specific functionality to the specialized classes.

Hey, there seems to be two APIs?

To make the Python API approachable, both if you come from the command line or are using the C++ API, we provide two interfaces to the detector. One is property based and tries to stay as close to the command line syntax as is possible, and the other one directly maps the C++ API found in Detector.h. There is also an underlying design reason for the two APIs since we auto generate the bindings to the C++ code using a mix of pybind11 and clang-tools. The property based API covers most of the functionality but in some cases you have to reach for the C++ like interface.

d = Detector()

# C++ like API
d.setExptime(0.1)

# or a bit more pythonic
d.exptime = 0.1

The c++ style API offers more control over access to individual modules in a large detector.

# Set exposure time for module 1, 5 and 7
d.setExptime(0.1, [1,5,7])

Finding functions

To find out which properties and methods that a Python object have you can use dir()

>>> from slsdet import Detector
>>> d = Detector()
>>> dir(d)
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__',
'__eq__', '__format__', '__ge__', '__getattribute__', '__gt__',
'__hash__', '__init__', '__init_subclass__', '__le__', '__len__',
'__lt__', '__module__', '__ne__', '__new__', '__reduce__',
'__reduce_ex__', '__repr__', '__setattr__', '__sizeof__',
'__str__', '__subclasshook__', '_adc_register', '_frozen',
'_register', 'acquire', 'adcclk', 'adcphase', 'adcpipeline',
'adcreg', 'asamples', 'auto_comp_disable', 'clearAcquiringFlag',
'clearBit', 'clearROI', 'client_version', 'config',
'counters', 'daclist', 'dacvalues', 'dbitclk', 'dbitphase' ...

Since the list for Detector is rather long it’s an good idea to filter it. The following example gives you properties and methods containing time in their name.

>>> [item for item in dir(d) if 'time' in item]
['compdisabletime', 'exptime', 'exptimel', 'frametime', 'getExptime',
'getExptimeForAllGates', 'getExptimeLeft', 'getSubExptime', 'patwaittime',
'patwaittime0', 'patwaittime1', 'patwaittime2', 'runtime', 'setExptime',
'setSubExptime', 'subdeadtime', 'subexptime']

The above method works on any Python object but for convenience we also included two functions to find names. View prints the names one per line while find returns a list of names.

from slsdet.lookup import view, find

>>> view('exptime')
exptime
exptimel
getExptime
getExptimeForAllGates
getExptimeLeft
getSubExptime
setExptime
setSubExptime
subexptime


>>> find('exptime')
['exptime', 'getExptime', 'getExptimeForAllGates', 'getExptimeLeft',
'getSubExptime', 'setExptime', 'setSubExptime', 'subexptime']

Finding out what the function does

To access the documentation of a function directly from the Python prompt use help().

>>> help(Detector.period)
Help on property:

    Period between frames, accepts either a value in seconds or datetime.timedelta

    Note
    -----
    :getter: always returns in seconds. To get in DurationWrapper, use getPeriod

    Example
    -----------
    >>> # setting directly in seconds
    >>> d.period = 1.05
    >>>
    >>> # setting directly in seconds
    >>> d.period = 5e-07
    >>>
    >>> # using timedelta (up to microseconds precision)
    >>> from datatime import timedelta
    >>> d.period = timedelta(seconds = 1, microseconds = 3)
    >>>
    >>> # using DurationWrapper to set in seconds
    >>> from slsdet import DurationWrapper
    >>> d.period = DurationWrapper(1.2)
    >>>
    >>> # using DurationWrapper to set in ns
    >>> t = DurationWrapper()
    >>> t.set_count(500)
    >>> d.period = t
    >>>
    >>> # to get in seconds
    >>> d.period
    181.23
    >>>
    >>> d.getExptime()
    [sls::DurationWrapper(total_seconds: 181.23 count: 181230000000)]

Where are the ENUMs?

To set some of the detector settings like file format you have to pass in an enum.

>>> d.setFileFormat(fileFormat.BINARY)

The enums can be found in slsdet.enums

import slsdet
>>> [e for e in dir(slsdet.enums) if not e.startswith('_')]
['M3_GainCaps', 'burstMode', 'clockIndex', 'cls', 'dacIndex', 'detectorSettings',
'detectorType', 'dimension', 'externalSignalFlag', 'fileFormat',
'frameDiscardPolicy', 'gainMode', 'name', 'polarity', 'portPosition',
'readoutMode', 'runStatus', 'speedLevel', 'streamingInterface', 'timingMode',
'timingSourceType', 'vetoAlgorithm']


# Even though importing using * is not recommended one could
# get all the enums like this:
>>> from slsdet.enums import *