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artiq/artiq/language/scan.py

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Python

"""
Implementation and management of scan objects.
A scan object (e.g. :class:`artiq.language.scan.RangeScan`) represents a
one-dimensional sweep of a numerical range. Multi-dimensional scans are
constructed by combining several scan objects, for example using
:class:`artiq.language.scan.MultiScanManager`.
Iterate on a scan object to scan it, e.g. ::
for variable in self.scan:
do_something(variable)
Iterating multiple times on the same scan object is possible, with the scan
yielding the same values each time. Iterating concurrently on the
same scan object (e.g. via nested loops) is also supported, and the
iterators are independent from each other.
"""
import random
import inspect
from itertools import product
from artiq.language.core import *
from artiq.language.environment import NoDefault, DefaultMissing
from artiq.language import units
__all__ = ["ScanObject",
"NoScan", "RangeScan", "ExplicitScan",
"Scannable", "MultiScanManager"]
class ScanObject:
pass
class NoScan(ScanObject):
"""A scan object that yields a single value for a specified number
of repetitions."""
def __init__(self, value, repetitions=1):
self.value = value
self.repetitions = repetitions
def _gen(self):
for i in range(self.repetitions):
yield self.value
def __iter__(self):
return self._gen()
def __len__(self):
return self.repetitions
def describe(self):
return {"ty": "NoScan", "value": self.value,
"repetitions": self.repetitions}
class RangeScan(ScanObject):
"""A scan object that yields a fixed number of evenly spaced values in a
range. If ``randomize`` is True the points are randomly ordered."""
def __init__(self, start, stop, npoints, randomize=False, seed=None):
self.start = start
self.stop = stop
self.npoints = npoints
self.randomize = randomize
self.seed = seed
if npoints == 0:
self.sequence = []
if npoints == 1:
self.sequence = [self.start]
else:
dx = (stop - start)/(npoints - 1)
self.sequence = [i*dx + start for i in range(npoints)]
if randomize:
rng = random.Random(seed)
random.shuffle(self.sequence, rng.random)
def __iter__(self):
return iter(self.sequence)
def __len__(self):
return self.npoints
def describe(self):
return {"ty": "RangeScan",
"start": self.start, "stop": self.stop,
"npoints": self.npoints,
"randomize": self.randomize,
"seed": self.seed}
class ExplicitScan(ScanObject):
"""A scan object that yields values from an explicitly defined sequence."""
def __init__(self, sequence):
self.sequence = sequence
def __iter__(self):
return iter(self.sequence)
def __len__(self):
return len(self.sequence)
def describe(self):
return {"ty": "ExplicitScan", "sequence": self.sequence}
_ty_to_scan = {
"NoScan": NoScan,
"RangeScan": RangeScan,
"ExplicitScan": ExplicitScan
}
class Scannable:
"""An argument (as defined in :class:`artiq.language.environment`) that
takes a scan object.
When ``scale`` is not specified, and the unit is a common one (i.e.
defined in ``artiq.language.units``), then the scale is obtained from
the unit using a simple string match. For example, milliseconds (``"ms"``)
units set the scale to 0.001. No unit (default) corresponds to a scale of
1.0.
For arguments with uncommon or complex units, use both the unit parameter
(a string for display) and the scale parameter (a numerical scale for
experiments).
For example, a scan shown between 1 xyz and 10 xyz in the GUI with
``scale=0.001`` and ``unit="xyz"`` results in values between 0.001 and
0.01 being scanned.
:param default: The default scan object. This parameter can be a list of
scan objects, in which case the first one is used as default and the
others are used to configure the default values of scan types that are
not initially selected in the GUI.
:param global_min: The minimum value taken by the scanned variable, common
to all scan modes. The user interface takes this value to set the
range of its input widgets.
:param global_max: Same as global_min, but for the maximum value.
:param global_step: The step with which the value should be modified by
up/down buttons in a user interface. The default is the scale divided
by 10.
:param unit: A string representing the unit of the scanned variable.
:param scale: A numerical scaling factor by which the displayed values
are multiplied when referenced in the experiment.
:param ndecimals: The number of decimals a UI should use.
"""
def __init__(self, default=NoDefault, unit="", scale=None,
global_step=None, global_min=None, global_max=None,
ndecimals=2):
if scale is None:
if unit == "":
scale = 1.0
else:
try:
scale = getattr(units, unit)
except AttributeError:
raise KeyError("Unit {} is unknown, you must specify "
"the scale manually".format(unit))
if global_step is None:
global_step = scale/10.0
if default is not NoDefault:
if not isinstance(default, list):
default = [default]
self.default_values = default
self.unit = unit
self.scale = scale
self.global_step = global_step
self.global_min = global_min
self.global_max = global_max
self.ndecimals = ndecimals
def default(self):
if not hasattr(self, "default_values"):
raise DefaultMissing
return self.default_values[0]
def process(self, x):
cls = _ty_to_scan[x["ty"]]
args = dict()
for arg in inspect.getargspec(cls).args[1:]:
if arg in x:
args[arg] = x[arg]
return cls(**args)
def describe(self):
d = {"ty": "Scannable"}
if hasattr(self, "default_values"):
d["default"] = [d.describe() for d in self.default_values]
d["unit"] = self.unit
d["scale"] = self.scale
d["global_step"] = self.global_step
d["global_min"] = self.global_min
d["global_max"] = self.global_max
d["ndecimals"] = self.ndecimals
return d
class MultiScanManager:
"""
Makes an iterator that returns elements from the first scan object until
it is exhausted, then proceeds to the next iterable, until all of the
scan objects are exhausted. Used for treating consecutive scans as a
single scan.
Scan objects must be passed as a list of tuples (name, scan_object).
Íteration produces scan points that have attributes that correspond
to the names of the scan objects, and have the last value yielded by
that scan object.
"""
def __init__(self, *args):
self.names = [a[0] for a in args]
self.scan_objects = [a[1] for a in args]
class ScanPoint:
def __init__(self, **kwargs):
self.attr = set()
for k, v in kwargs.items():
setattr(self, k, v)
self.attr.add(k)
def __repr__(self):
return ("<ScanPoint " +
" ".join("{}={}".format(k, getattr(self, k))
for k in self.attr) +
">")
self.scan_point_cls = ScanPoint
def _gen(self):
for values in product(*self.scan_objects):
d = {k: v for k, v in zip(self.names, values)}
yield self.scan_point_cls(**d)
def __iter__(self):
return self._gen()