"""
Collection of either extremely generic or simple Operation
examples.
"""
from __future__ import division
from distutils.version import LooseVersion
import numpy as np
import param
from param import _is_number
from ..core import (Operation, NdOverlay, Overlay, GridMatrix,
HoloMap, Dataset, Element, Collator, Dimension)
from ..core.data import ArrayInterface, DictInterface, default_datatype
from ..core.util import (group_sanitizer, label_sanitizer, pd,
basestring, datetime_types, isfinite, dt_to_int,
isdatetime, is_dask_array, is_cupy_array)
from ..element.chart import Histogram, Scatter
from ..element.raster import Image, RGB
from ..element.path import Contours, Polygons
from ..element.util import categorical_aggregate2d # noqa (API import)
from ..streams import RangeXY
column_interfaces = [ArrayInterface, DictInterface]
if pd:
from ..core.data import PandasInterface
column_interfaces.append(PandasInterface)
def identity(x,k): return x
[docs]class operation(Operation):
"""
The most generic operation that wraps any callable into an
Operation. The callable needs to accept an HoloViews
component and a key (that may be ignored) and must return a new
HoloViews component.
This class may be useful for turning a HoloViews method into an
operation to define as compositor operation. For instance, the
following definition:
operation.instance(op=lambda x, k: x.collapse(np.subtract))
Could be used to implement a collapse operation to subtracts the
data between Rasters in an Overlay.
"""
output_type = param.Parameter(None, doc="""
The output element type which may be None to disable type
checking.
May be used to declare useful information to other code in
HoloViews e.g required for tab-completion support of operations
registered with compositors.""")
group = param.String(default='Operation', doc="""
The group assigned to the result after having applied the
operator.""")
op = param.Callable(default=identity, doc="""
The operation used to generate a new HoloViews object returned
by the operation. By default, the identity operation is
applied.""")
def _process(self, view, key=None):
retval = self.p.op(view, key)
if (self.p.output_type is not None):
assert isinstance(retval, self.p.output_type), \
"Return value does not match the declared output type."
return retval.relabel(group=self.p.group)
[docs]class factory(Operation):
"""
Simple operation that constructs any element that accepts some
other element as input. For instance, RGB and HSV elements can be
created from overlays of Image elements.
"""
output_type = param.Parameter(RGB, doc="""
The output type of the factor operation.
By default, if three overlaid Images elements are supplied,
the corresponding RGB element will be returned. """)
args = param.List(default=[], doc="""
The list of positional argument to pass to the factory""")
kwargs = param.Dict(default={}, doc="""
The dict of keyword arguments to pass to the factory""")
def _process(self, view, key=None):
return self.p.output_type(view, *self.p.args, **self.p.kwargs)
[docs]class function(Operation):
output_type = param.ClassSelector(class_=type, doc="""
The output type of the method operation""")
input_type = param.ClassSelector(class_=type, doc="""
The object type the method is defined on""")
fn = param.Callable(default=lambda el, *args, **kwargs: el, doc="""
The function to apply.""")
args = param.List(default=[], doc="""
The list of positional argument to pass to the method""")
kwargs = param.Dict(default={}, doc="""
The dict of keyword arguments to pass to the method""")
def _process(self, element, key=None):
return self.p.fn(element, *self.p.args, **self.p.kwargs)
[docs]class method(Operation):
"""
Operation that wraps a method call
"""
output_type = param.ClassSelector(class_=type, doc="""
The output type of the method operation""")
input_type = param.ClassSelector(class_=type, doc="""
The object type the method is defined on""")
method_name = param.String(default='__call__', doc="""
The method name""")
args = param.List(default=[], doc="""
The list of positional argument to pass to the method""")
kwargs = param.Dict(default={}, doc="""
The dict of keyword arguments to pass to the method""")
def _process(self, element, key=None):
fn = getattr(self.p.input_type, self.p.method_name)
return fn(element, *self.p.args, **self.p.kwargs)
[docs]class apply_when(param.ParameterizedFunction):
"""
Applies a selection depending on the current zoom range. If the
supplied predicate function returns a True it will apply the
operation otherwise it will return the raw element after the
selection. For example the following will apply datashading if
the number of points in the current viewport exceed 1000 otherwise
just returning the selected points element:
apply_when(points, operation=datashade, predicate=lambda x: x > 1000)
"""
operation = param.Callable(default=lambda x: x)
predicate = param.Callable(default=None)
def _apply(self, element, x_range, y_range, invert=False):
selected = element
if x_range is not None and y_range is not None:
selected = element[x_range, y_range]
condition = self.predicate(selected)
if (not invert and condition) or (invert and not condition):
return selected
elif selected.interface.gridded:
return selected.clone([])
else:
return selected.iloc[:0]
def __call__(self, obj, **params):
if 'streams' in params:
streams = params.pop('streams')
else:
streams = [RangeXY()]
self.param.set_param(**params)
if not self.predicate:
raise ValueError(
'Must provide a predicate function to determine when '
'to apply the operation and when to return the selected '
'data.'
)
applied = self.operation(obj.apply(self._apply, streams=streams))
raw = obj.apply(self._apply, streams=streams, invert=True)
return applied * raw
[docs]class chain(Operation):
"""
Defining an Operation chain is an easy way to define a new
Operation from a series of existing ones. The argument is a
list of Operation (or Operation instances) that are
called in sequence to generate the returned element.
chain(operations=[gradient, threshold.instance(level=2)])
This operation can accept an Image instance and would first
compute the gradient before thresholding the result at a level of
2.0.
Instances are only required when arguments need to be passed to
individual operations so the resulting object is a function over a
single argument.
"""
output_type = param.Parameter(Image, doc="""
The output type of the chain operation. Must be supplied if
the chain is to be used as a channel operation.""")
group = param.String(default='', doc="""
The group assigned to the result after having applied the chain.
Defaults to the group produced by the last operation in the chain""")
operations = param.List(default=[], class_=Operation, doc="""
A list of Operations (or Operation instances)
that are applied on the input from left to right.""")
def _process(self, view, key=None):
processed = view
for i, operation in enumerate(self.p.operations):
processed = operation.process_element(
processed, key, input_ranges=self.p.input_ranges
)
if not self.p.group:
return processed
else:
return processed.clone(group=self.p.group)
[docs]class image_overlay(Operation):
"""
Operation to build a overlay of images to a specification from a
subset of the required elements.
This is useful for reordering the elements of an overlay,
duplicating layers of an overlay or creating blank image elements
in the appropriate positions.
For instance, image_overlay may build a three layered input
suitable for the RGB factory operation even if supplied with one
or two of the required channels (creating blank channels for the
missing elements).
Note that if there is any ambiguity regarding the match, the
strongest match will be used. In the case of a tie in match
strength, the first layer in the input is used. One successful
match is always required.
"""
output_type = Overlay
spec = param.String(doc="""
Specification of the output Overlay structure. For instance:
Image.R * Image.G * Image.B
Will ensure an overlay of this structure is created even if
(for instance) only (Image.R * Image.B) is supplied.
Elements in the input overlay that match are placed in the
appropriate positions and unavailable specification elements
are created with the specified fill group.""")
fill = param.Number(default=0)
default_range = param.Tuple(default=(0,1), doc="""
The default range that will be set on the value_dimension of
any automatically created blank image elements.""")
group = param.String(default='Transform', doc="""
The group assigned to the resulting overlay.""")
@classmethod
def _match(cls, el, spec):
"Return the strength of the match (None if no match)"
spec_dict = dict(zip(['type', 'group', 'label'], spec.split('.')))
if not isinstance(el, Image) or spec_dict['type'] != 'Image':
raise NotImplementedError("Only Image currently supported")
sanitizers = {'group':group_sanitizer, 'label':label_sanitizer}
strength = 1
for key in ['group', 'label']:
attr_value = sanitizers[key](getattr(el, key))
if key in spec_dict:
if spec_dict[key] != attr_value: return None
strength += 1
return strength
def _match_overlay(self, raster, overlay_spec):
"""
Given a raster or input overlay, generate a list of matched
elements (None if no match) and corresponding tuple of match
strength values.
"""
ordering = [None]*len(overlay_spec) # Elements to overlay
strengths = [0]*len(overlay_spec) # Match strengths
elements = raster.values() if isinstance(raster, Overlay) else [raster]
for el in elements:
for pos in range(len(overlay_spec)):
strength = self._match(el, overlay_spec[pos])
if strength is None: continue # No match
elif (strength <= strengths[pos]): continue # Weaker match
else: # Stronger match
ordering[pos] = el
strengths[pos] = strength
return ordering, strengths
def _process(self, raster, key=None):
specs = tuple(el.strip() for el in self.p.spec.split('*'))
ordering, strengths = self._match_overlay(raster, specs)
if all(el is None for el in ordering):
raise Exception("The image_overlay operation requires at least one match")
completed = []
strongest = ordering[np.argmax(strengths)]
for el, spec in zip(ordering, specs):
if el is None:
spec_dict = dict(zip(['type', 'group', 'label'], spec.split('.')))
el = Image(np.ones(strongest.data.shape) * self.p.fill,
group=spec_dict.get('group','Image'),
label=spec_dict.get('label',''))
el.vdims[0].range = self.p.default_range
completed.append(el)
return np.prod(completed)
[docs]class threshold(Operation):
"""
Threshold a given Image whereby all values higher than a given
level map to the specified high value and all values lower than
that level map to the specified low value.
"""
output_type = Image
level = param.Number(default=0.5, doc="""
The value at which the threshold is applied. Values lower than
the threshold map to the 'low' value and values above map to
the 'high' value.""")
high = param.Number(default=1.0, doc="""
The value given to elements greater than (or equal to) the
threshold.""")
low = param.Number(default=0.0, doc="""
The value given to elements below the threshold.""")
group = param.String(default='Threshold', doc="""
The group assigned to the thresholded output.""")
_per_element = True
def _process(self, matrix, key=None):
if not isinstance(matrix, Image):
raise TypeError("The threshold operation requires a Image as input.")
arr = matrix.data
high = np.ones(arr.shape) * self.p.high
low = np.ones(arr.shape) * self.p.low
thresholded = np.where(arr > self.p.level, high, low)
return matrix.clone(thresholded, group=self.p.group)
[docs]class gradient(Operation):
"""
Compute the gradient plot of the supplied Image.
If the Image value dimension is cyclic, the smallest step is taken
considered the cyclic range
"""
output_type = Image
group = param.String(default='Gradient', doc="""
The group assigned to the output gradient matrix.""")
_per_element = True
def _process(self, matrix, key=None):
if len(matrix.vdims) != 1:
raise ValueError("Input matrix to gradient operation must "
"have single value dimension.")
matrix_dim = matrix.vdims[0]
data = np.flipud(matrix.dimension_values(matrix_dim, flat=False))
r, c = data.shape
if matrix_dim.cyclic and (None in matrix_dim.range):
raise Exception("Cyclic range must be specified to compute "
"the gradient of cyclic quantities")
cyclic_range = None if not matrix_dim.cyclic else np.diff(matrix_dim.range)
if cyclic_range is not None:
# shift values such that wrapping works ok
data = data - matrix_dim.range[0]
dx = np.diff(data, 1, axis=1)[0:r-1, 0:c-1]
dy = np.diff(data, 1, axis=0)[0:r-1, 0:c-1]
if cyclic_range is not None: # Wrap into the specified range
# Convert negative differences to an equivalent positive value
dx = dx % cyclic_range
dy = dy % cyclic_range
#
# Prefer small jumps
dx_negatives = dx - cyclic_range
dy_negatives = dy - cyclic_range
dx = np.where(np.abs(dx_negatives)<dx, dx_negatives, dx)
dy = np.where(np.abs(dy_negatives)<dy, dy_negatives, dy)
return Image(np.sqrt(dx * dx + dy * dy), bounds=matrix.bounds, group=self.p.group)
[docs]class convolve(Operation):
"""
Apply a convolution to an overlay using the top layer as the
kernel for convolving the bottom layer. Both Image elements in
the input overlay should have a single value dimension.
"""
output_type = Image
group = param.String(default='Convolution', doc="""
The group assigned to the convolved output.""")
kernel_roi = param.NumericTuple(default=(0,0,0,0), length=4, doc="""
A 2-dimensional slice of the kernel layer to use in the
convolution in lbrt (left, bottom, right, top) format. By
default, no slicing is applied.""")
_per_element = True
def _process(self, overlay, key=None):
if len(overlay) != 2:
raise Exception("Overlay must contain at least to items.")
[target, kernel] = overlay.get(0), overlay.get(1)
if len(target.vdims) != 1:
raise Exception("Convolution requires inputs with single value dimensions.")
xslice = slice(self.p.kernel_roi[0], self.p.kernel_roi[2])
yslice = slice(self.p.kernel_roi[1], self.p.kernel_roi[3])
k = kernel.data if self.p.kernel_roi == (0,0,0,0) else kernel[xslice, yslice].data
data = np.flipud(target.dimension_values(2, flat=False))
fft1 = np.fft.fft2(data)
fft2 = np.fft.fft2(k, s=data.shape)
convolved_raw = np.fft.ifft2(fft1 * fft2).real
k_rows, k_cols = k.shape
rolled = np.roll(np.roll(convolved_raw, -(k_cols//2), axis=-1), -(k_rows//2), axis=-2)
convolved = rolled / float(k.sum())
return Image(convolved, bounds=target.bounds, group=self.p.group)
[docs]class contours(Operation):
"""
Given a Image with a single channel, annotate it with contour
lines for a given set of contour levels.
The return is an NdOverlay with a Contours layer for each given
level, overlaid on top of the input Image.
"""
output_type = Overlay
levels = param.ClassSelector(default=10, class_=(list, int), doc="""
A list of scalar values used to specify the contour levels.""")
group = param.String(default='Level', doc="""
The group assigned to the output contours.""")
filled = param.Boolean(default=False, doc="""
Whether to generate filled contours""")
overlaid = param.Boolean(default=False, doc="""
Whether to overlay the contour on the supplied Element.""")
_per_element = True
def _process(self, element, key=None):
try:
from matplotlib.contour import QuadContourSet
from matplotlib.axes import Axes
from matplotlib.figure import Figure
from matplotlib.dates import num2date, date2num
except ImportError:
raise ImportError("contours operation requires matplotlib.")
extent = element.range(0) + element.range(1)[::-1]
xs = element.dimension_values(0, True, flat=False)
ys = element.dimension_values(1, True, flat=False)
zs = element.dimension_values(2, flat=False)
# Ensure that coordinate arrays specify bin centers
if xs.shape[0] != zs.shape[0]:
xs = xs[:-1] + np.diff(xs, axis=0)/2.
if xs.shape[1] != zs.shape[1]:
xs = xs[:, :-1] + (np.diff(xs, axis=1)/2.)
if ys.shape[0] != zs.shape[0]:
ys = ys[:-1] + np.diff(ys, axis=0)/2.
if ys.shape[1] != zs.shape[1]:
ys = ys[:, :-1] + (np.diff(ys, axis=1)/2.)
data = (xs, ys, zs)
# if any data is a datetime, transform to matplotlib's numerical format
data_is_datetime = tuple(isdatetime(arr) for k, arr in enumerate(data))
if any(data_is_datetime):
data = tuple(
date2num(d) if is_datetime else d
for d, is_datetime in zip(data, data_is_datetime)
)
xdim, ydim = element.dimensions('key', label=True)
if self.p.filled:
contour_type = Polygons
else:
contour_type = Contours
vdims = element.vdims[:1]
kwargs = {}
levels = self.p.levels
zmin, zmax = element.range(2)
if isinstance(self.p.levels, int):
if zmin == zmax:
contours = contour_type([], [xdim, ydim], vdims)
return (element * contours) if self.p.overlaid else contours
data += (levels,)
else:
kwargs = {'levels': levels}
fig = Figure()
ax = Axes(fig, [0, 0, 1, 1])
contour_set = QuadContourSet(ax, *data, filled=self.p.filled,
extent=extent, **kwargs)
levels = np.array(contour_set.get_array())
crange = levels.min(), levels.max()
if self.p.filled:
levels = levels[:-1] + np.diff(levels)/2.
vdims = [vdims[0].clone(range=crange)]
paths = []
empty = np.array([[np.nan, np.nan]])
for level, cset in zip(levels, contour_set.collections):
exteriors = []
interiors = []
for geom in cset.get_paths():
interior = []
polys = geom.to_polygons(closed_only=False)
for ncp, cp in enumerate(polys):
if any(data_is_datetime[0:2]):
# transform x/y coordinates back to datetimes
xs, ys = np.split(cp, 2, axis=1)
if data_is_datetime[0]:
xs = np.array(num2date(xs))
if data_is_datetime[1]:
ys = np.array(num2date(ys))
cp = np.concatenate((xs, ys), axis=1)
if ncp == 0:
exteriors.append(cp)
exteriors.append(empty)
else:
interior.append(cp)
if len(polys):
interiors.append(interior)
if not exteriors:
continue
geom = {
element.vdims[0].name:
num2date(level) if data_is_datetime[2] else level,
(xdim, ydim): np.concatenate(exteriors[:-1])
}
if self.p.filled and interiors:
geom['holes'] = interiors
paths.append(geom)
contours = contour_type(paths, label=element.label, kdims=element.kdims, vdims=vdims)
if self.p.overlaid:
contours = element * contours
return contours
[docs]class histogram(Operation):
"""
Returns a Histogram of the input element data, binned into
num_bins over the bin_range (if specified) along the specified
dimension.
"""
bin_range = param.NumericTuple(default=None, length=2, doc="""
Specifies the range within which to compute the bins.""")
bins = param.ClassSelector(default=None, class_=(np.ndarray, list, tuple, str), doc="""
An explicit set of bin edges or a method to find the optimal
set of bin edges, e.g. 'auto', 'fd', 'scott' etc. For more
documentation on these approaches see the np.histogram_bin_edges
documentation.""")
cumulative = param.Boolean(default=False, doc="""
Whether to compute the cumulative histogram""")
dimension = param.String(default=None, doc="""
Along which dimension of the Element to compute the histogram.""")
frequency_label = param.String(default=None, doc="""
Format string defining the label of the frequency dimension of the Histogram.""")
groupby = param.ClassSelector(default=None, class_=(basestring, Dimension), doc="""
Defines a dimension to group the Histogram returning an NdOverlay of Histograms.""")
log = param.Boolean(default=False, doc="""
Whether to use base 10 logarithmic samples for the bin edges.""")
mean_weighted = param.Boolean(default=False, doc="""
Whether the weighted frequencies are averaged.""")
normed = param.ObjectSelector(default=True,
objects=[True, False, 'integral', 'height'],
doc="""
Controls normalization behavior. If `True` or `'integral'`, then
`density=True` is passed to np.histogram, and the distribution
is normalized such that the integral is unity. If `False`,
then the frequencies will be raw counts. If `'height'`, then the
frequencies are normalized such that the max bin height is unity.""")
nonzero = param.Boolean(default=False, doc="""
Whether to use only nonzero values when computing the histogram""")
num_bins = param.Integer(default=20, doc="""
Number of bins in the histogram .""")
weight_dimension = param.String(default=None, doc="""
Name of the dimension the weighting should be drawn from""")
style_prefix = param.String(default=None, allow_None=None, doc="""
Used for setting a common style for histograms in a HoloMap or AdjointLayout.""")
def _process(self, element, key=None):
if self.p.groupby:
if not isinstance(element, Dataset):
raise ValueError('Cannot use histogram groupby on non-Dataset Element')
grouped = element.groupby(self.p.groupby, group_type=Dataset, container_type=NdOverlay)
self.p.groupby = None
return grouped.map(self._process, Dataset)
normed = False if self.p.mean_weighted and self.p.weight_dimension else self.p.normed
if self.p.dimension:
selected_dim = self.p.dimension
else:
selected_dim = [d.name for d in element.vdims + element.kdims][0]
dim = element.get_dimension(selected_dim)
if hasattr(element, 'interface'):
data = element.interface.values(element, selected_dim, compute=False)
else:
data = element.dimension_values(selected_dim)
is_datetime = isdatetime(data)
if is_datetime:
data = data.astype('datetime64[ns]').astype('int64')
# Handle different datatypes
is_finite = isfinite
is_cupy = is_cupy_array(data)
if is_cupy:
import cupy
full_cupy_support = LooseVersion(cupy.__version__) > '8.0'
if not full_cupy_support and (normed or self.p.weight_dimension):
data = cupy.asnumpy(data)
is_cupy = False
if is_dask_array(data):
import dask.array as da
histogram = da.histogram
elif is_cupy:
import cupy
histogram = cupy.histogram
is_finite = cupy.isfinite
else:
histogram = np.histogram
# Mask data
mask = is_finite(data)
if self.p.nonzero:
mask = mask & (data > 0)
data = data[mask]
# Compute weights
if self.p.weight_dimension:
if hasattr(element, 'interface'):
weights = element.interface.values(element, self.p.weight_dimension, compute=False)
else:
weights = element.dimension_values(self.p.weight_dimension)
if self.p.nonzero:
weights = weights[mask]
else:
weights = None
# Compute bins
if isinstance(self.p.bins, str):
bin_data = cupy.asnumpy(data) if is_cupy else data
edges = np.histogram_bin_edges(bin_data, bins=self.p.bins)
elif isinstance(self.p.bins, (list, np.ndarray)):
edges = self.p.bins
if isdatetime(edges):
edges = edges.astype('datetime64[ns]').astype('int64')
else:
hist_range = self.p.bin_range or element.range(selected_dim)
# Avoids range issues including zero bin range and empty bins
if hist_range == (0, 0) or any(not isfinite(r) for r in hist_range):
hist_range = (0, 1)
steps = self.p.num_bins + 1
start, end = hist_range
if is_datetime:
start, end = dt_to_int(start, 'ns'), dt_to_int(end, 'ns')
if self.p.log:
bin_min = max([abs(start), data[data>0].min()])
edges = np.logspace(np.log10(bin_min), np.log10(end), steps)
else:
edges = np.linspace(start, end, steps)
if is_cupy:
edges = cupy.asarray(edges)
if is_dask_array(data) or len(data):
if is_cupy and not full_cupy_support:
hist, _ = histogram(data, bins=edges)
elif normed:
# This covers True, 'height', 'integral'
hist, edges = histogram(data, density=True,
weights=weights, bins=edges)
if normed == 'height':
hist /= hist.max()
else:
hist, edges = histogram(data, normed=normed, weights=weights, bins=edges)
if self.p.weight_dimension and self.p.mean_weighted:
hist_mean, _ = histogram(data, density=False, bins=self.p.num_bins)
hist /= hist_mean
else:
nbins = self.p.num_bins if self.p.bins is None else len(self.p.bins)-1
hist = np.zeros(nbins)
if is_cupy_array(hist):
edges = cupy.asnumpy(edges)
hist = cupy.asnumpy(hist)
hist[np.isnan(hist)] = 0
if is_datetime:
edges = (edges/1e3).astype('datetime64[us]')
params = {}
if self.p.weight_dimension:
params['vdims'] = [element.get_dimension(self.p.weight_dimension)]
elif self.p.frequency_label:
label = self.p.frequency_label.format(dim=dim.pprint_label)
params['vdims'] = [Dimension('Frequency', label=label)]
else:
label = 'Frequency' if normed else 'Count'
params['vdims'] = [Dimension('{0}_{1}'.format(dim.name, label.lower()),
label=label)]
if element.group != element.__class__.__name__:
params['group'] = element.group
if self.p.cumulative:
hist = np.cumsum(hist)
if self.p.normed in (True, 'integral'):
hist *= edges[1]-edges[0]
# Save off the computed bin edges so that if this operation instance
# is used to compute another histogram, it will default to the same
# bin edges.
self.bins = list(edges)
return Histogram((edges, hist), kdims=[element.get_dimension(selected_dim)],
label=element.label, **params)
[docs]class decimate(Operation):
"""
Decimates any column based Element to a specified number of random
rows if the current element defined by the x_range and y_range
contains more than max_samples. By default the operation returns a
DynamicMap with a RangeXY stream allowing dynamic downsampling.
"""
dynamic = param.Boolean(default=True, doc="""
Enables dynamic processing by default.""")
link_inputs = param.Boolean(default=True, doc="""
By default, the link_inputs parameter is set to True so that
when applying shade, backends that support linked streams
update RangeXY streams on the inputs of the shade operation.""")
max_samples = param.Integer(default=5000, doc="""
Maximum number of samples to display at the same time.""")
random_seed = param.Integer(default=42, doc="""
Seed used to initialize randomization.""")
streams = param.List(default=[RangeXY], doc="""
List of streams that are applied if dynamic=True, allowing
for dynamic interaction with the plot.""")
x_range = param.NumericTuple(default=None, length=2, doc="""
The x_range as a tuple of min and max x-value. Auto-ranges
if set to None.""")
y_range = param.NumericTuple(default=None, length=2, doc="""
The x_range as a tuple of min and max y-value. Auto-ranges
if set to None.""")
_per_element = True
def _process_layer(self, element, key=None):
if not isinstance(element, Dataset):
raise ValueError("Cannot downsample non-Dataset types.")
if element.interface not in column_interfaces:
element = element.clone(tuple(element.columns().values()))
xstart, xend = self.p.x_range if self.p.x_range else element.range(0)
ystart, yend = self.p.y_range if self.p.y_range else element.range(1)
# Slice element to current ranges
xdim, ydim = element.dimensions(label=True)[0:2]
sliced = element.select(**{xdim: (xstart, xend),
ydim: (ystart, yend)})
if len(sliced) > self.p.max_samples:
prng = np.random.RandomState(self.p.random_seed)
return sliced.iloc[prng.choice(len(sliced), self.p.max_samples, False)]
return sliced
def _process(self, element, key=None):
return element.map(self._process_layer, Element)
[docs]class interpolate_curve(Operation):
"""
Resamples a Curve using the defined interpolation method, e.g.
to represent changes in y-values as steps.
"""
interpolation = param.ObjectSelector(objects=['steps-pre', 'steps-mid',
'steps-post', 'linear'],
default='steps-mid', doc="""
Controls the transition point of the step along the x-axis.""")
_per_element = True
@classmethod
def pts_to_prestep(cls, x, values):
steps = np.zeros(2 * len(x) - 1)
value_steps = tuple(np.empty(2 * len(x) - 1, dtype=v.dtype) for v in values)
steps[0::2] = x
steps[1::2] = steps[0:-2:2]
val_arrays = []
for v, s in zip(values, value_steps):
s[0::2] = v
s[1::2] = s[2::2]
val_arrays.append(s)
return steps, tuple(val_arrays)
@classmethod
def pts_to_midstep(cls, x, values):
steps = np.zeros(2 * len(x))
value_steps = tuple(np.empty(2 * len(x), dtype=v.dtype) for v in values)
steps[1:-1:2] = steps[2::2] = x[:-1] + (x[1:] - x[:-1])/2
steps[0], steps[-1] = x[0], x[-1]
val_arrays = []
for v, s in zip(values, value_steps):
s[0::2] = v
s[1::2] = s[0::2]
val_arrays.append(s)
return steps, tuple(val_arrays)
@classmethod
def pts_to_poststep(cls, x, values):
steps = np.zeros(2 * len(x) - 1)
value_steps = tuple(np.empty(2 * len(x) - 1, dtype=v.dtype) for v in values)
steps[0::2] = x
steps[1::2] = steps[2::2]
val_arrays = []
for v, s in zip(values, value_steps):
s[0::2] = v
s[1::2] = s[0:-2:2]
val_arrays.append(s)
return steps, tuple(val_arrays)
def _process_layer(self, element, key=None):
INTERPOLATE_FUNCS = {'steps-pre': self.pts_to_prestep,
'steps-mid': self.pts_to_midstep,
'steps-post': self.pts_to_poststep}
if self.p.interpolation not in INTERPOLATE_FUNCS:
return element
x = element.dimension_values(0)
is_datetime = isdatetime(x)
if is_datetime:
dt_type = 'datetime64[ns]'
x = x.astype(dt_type)
dvals = tuple(element.dimension_values(d) for d in element.dimensions()[1:])
xs, dvals = INTERPOLATE_FUNCS[self.p.interpolation](x, dvals)
if is_datetime:
xs = xs.astype(dt_type)
return element.clone((xs,)+dvals)
def _process(self, element, key=None):
return element.map(self._process_layer, Element)
#==================#
# Other operations #
#==================#
[docs]class collapse(Operation):
"""
Given an overlay of Element types, collapse into single Element
object using supplied function. Collapsing aggregates over the
key dimensions of each object applying the supplied fn to each group.
This is an example of an Operation that does not involve
any Raster types.
"""
fn = param.Callable(default=np.mean, doc="""
The function that is used to collapse the curve y-values for
each x-value.""")
def _process(self, overlay, key=None):
if isinstance(overlay, NdOverlay):
collapse_map = HoloMap(overlay)
else:
collapse_map = HoloMap({i: el for i, el in enumerate(overlay)})
return collapse_map.collapse(function=self.p.fn)
[docs]class gridmatrix(param.ParameterizedFunction):
"""
The gridmatrix operation takes an Element or HoloMap
of Elements as input and creates a GridMatrix object,
which plots each dimension in the Element against
each other dimension. This provides a very useful
overview of high-dimensional data and is inspired
by pandas and seaborn scatter_matrix implementations.
"""
chart_type = param.Parameter(default=Scatter, doc="""
The Element type used to display bivariate distributions
of the data.""")
diagonal_type = param.Parameter(default=None, doc="""
The Element type along the diagonal, may be a Histogram or any
other plot type which can visualize a univariate distribution.
This parameter overrides diagonal_operation.""")
diagonal_operation = param.Parameter(default=histogram, doc="""
The operation applied along the diagonal, may be a histogram-operation
or any other function which returns a viewable element.""")
overlay_dims = param.List(default=[], doc="""
If a HoloMap is supplied this will allow overlaying one or
more of it's key dimensions.""")
def __call__(self, data, **params):
p = param.ParamOverrides(self, params)
if isinstance(data, (HoloMap, NdOverlay)):
ranges = {d.name: data.range(d) for d in data.dimensions()}
data = data.clone({k: GridMatrix(self._process(p, v, ranges))
for k, v in data.items()})
data = Collator(data, merge_type=type(data))()
if p.overlay_dims:
data = data.map(lambda x: x.overlay(p.overlay_dims), (HoloMap,))
return data
elif isinstance(data, Element):
data = self._process(p, data)
return GridMatrix(data)
def _process(self, p, element, ranges={}):
# Creates a unified Dataset.data attribute
# to draw the data from
if isinstance(element.data, np.ndarray):
el_data = element.table(default_datatype)
else:
el_data = element.data
# Get dimensions to plot against each other
types = (str, basestring, np.str_, np.object_)+datetime_types
dims = [d for d in element.dimensions()
if _is_number(element.range(d)[0]) and
not issubclass(element.get_dimension_type(d), types)]
permuted_dims = [(d1, d2) for d1 in dims
for d2 in dims[::-1]]
# Convert Histogram type to operation to avoid one case in the if below.
if p.diagonal_type is Histogram:
p.diagonal_type = None
p.diagonal_operation = histogram
data = {}
for d1, d2 in permuted_dims:
if d1 == d2:
if p.diagonal_type is not None:
if p.diagonal_type._auto_indexable_1d:
el = p.diagonal_type(el_data, kdims=[d1], vdims=[d2],
datatype=[default_datatype])
else:
values = element.dimension_values(d1)
el = p.diagonal_type(values, kdims=[d1])
elif p.diagonal_operation is None:
continue
elif p.diagonal_operation is histogram or isinstance(p.diagonal_operation, histogram):
bin_range = ranges.get(d1.name, element.range(d1))
el = p.diagonal_operation(element, dimension=d1.name, bin_range=bin_range)
else:
el = p.diagonal_operation(element, dimension=d1.name)
else:
kdims, vdims = ([d1, d2], []) if len(p.chart_type.kdims) == 2 else (d1, d2)
el = p.chart_type(el_data, kdims=kdims, vdims=vdims,
datatype=[default_datatype])
data[(d1.name, d2.name)] = el
return data
