Source code for qiskit.visualization.dag_visualization
# This code is part of Qiskit.
#
# (C) Copyright IBM 2017, 2018, 2020.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
# pylint: disable=invalid-name
"""
Visualization function for DAG circuit representation.
"""
import os
import sys
import tempfile
from qiskit.exceptions import MissingOptionalLibraryError
from .exceptions import VisualizationError
try:
from PIL import Image
HAS_PIL = True
except ImportError:
HAS_PIL = False
[docs]def dag_drawer(dag, scale=0.7, filename=None, style="color"):
"""Plot the directed acyclic graph (dag) to represent operation dependencies
in a quantum circuit.
Note this function leverages
`pydot <https://github.com/erocarrera/pydot>`_ to generate the graph, which
means that having `Graphviz <https://www.graphviz.org/>`_ installed on your
system is required for this to work.
The current release of Graphviz can be downloaded here: <https://graphviz.gitlab.io/download/>.
Download the version of the software that matches your environment and follow the instructions
to install Graph Visualization Software (Graphviz) on your operating system.
Args:
dag (DAGCircuit): The dag to draw.
scale (float): scaling factor
filename (str): file path to save image to (format inferred from name)
style (str): 'plain': B&W graph
'color' (default): color input/output/op nodes
Returns:
PIL.Image: if in Jupyter notebook and not saving to file,
otherwise None.
Raises:
VisualizationError: when style is not recognized.
MissingOptionalLibraryError: when pydot or pillow are not installed.
Example:
.. jupyter-execute::
%matplotlib inline
from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit
from qiskit.dagcircuit import DAGCircuit
from qiskit.converters import circuit_to_dag
from qiskit.visualization import dag_drawer
q = QuantumRegister(3, 'q')
c = ClassicalRegister(3, 'c')
circ = QuantumCircuit(q, c)
circ.h(q[0])
circ.cx(q[0], q[1])
circ.measure(q[0], c[0])
circ.rz(0.5, q[1]).c_if(c, 2)
dag = circuit_to_dag(circ)
dag_drawer(dag)
"""
try:
import pydot
except ImportError as ex:
raise MissingOptionalLibraryError(
libname="PyDot",
name="dag_drawer",
pip_install="pip install pydot",
) from ex
# NOTE: use type str checking to avoid potential cyclical import
# the two tradeoffs ere that it will not handle subclasses and it is
# slower (which doesn't matter for a visualization function)
type_str = str(type(dag))
if "DAGDependency" in type_str:
graph_attrs = {"dpi": str(100 * scale)}
def node_attr_func(node):
if style == "plain":
return {}
if style == "color":
n = {}
n["label"] = str(node.node_id) + ": " + str(node.name)
if node.name == "measure":
n["color"] = "blue"
n["style"] = "filled"
n["fillcolor"] = "lightblue"
if node.name == "barrier":
n["color"] = "black"
n["style"] = "filled"
n["fillcolor"] = "green"
if node.op._directive:
n["color"] = "black"
n["style"] = "filled"
n["fillcolor"] = "red"
if node.op.condition:
n["label"] = str(node.node_id) + ": " + str(node.name) + " (conditional)"
n["color"] = "black"
n["style"] = "filled"
n["fillcolor"] = "lightgreen"
return n
else:
raise VisualizationError("Unrecognized style %s for the dag_drawer." % style)
edge_attr_func = None
else:
bit_labels = {
bit: f"{reg.name}[{idx}]"
for reg in list(dag.qregs.values()) + list(dag.cregs.values())
for (idx, bit) in enumerate(reg)
}
graph_attrs = {"dpi": str(100 * scale)}
def node_attr_func(node):
if style == "plain":
return {}
if style == "color":
n = {}
if node.type == "op":
n["label"] = node.name
n["color"] = "blue"
n["style"] = "filled"
n["fillcolor"] = "lightblue"
if node.type == "in":
n["label"] = bit_labels[node.wire]
n["color"] = "black"
n["style"] = "filled"
n["fillcolor"] = "green"
if node.type == "out":
n["label"] = bit_labels[node.wire]
n["color"] = "black"
n["style"] = "filled"
n["fillcolor"] = "red"
return n
else:
raise VisualizationError("Invalid style %s" % style)
def edge_attr_func(edge):
e = {}
e["label"] = bit_labels[edge]
return e
dot_str = dag._multi_graph.to_dot(node_attr_func, edge_attr_func, graph_attrs)
dot = pydot.graph_from_dot_data(dot_str)[0]
if filename:
extension = filename.split(".")[-1]
dot.write(filename, format=extension)
return None
elif ("ipykernel" in sys.modules) and ("spyder" not in sys.modules):
if not HAS_PIL:
raise MissingOptionalLibraryError(
libname="pillow",
name="dag_drawer",
pip_install="pip install pillow",
)
with tempfile.TemporaryDirectory() as tmpdirname:
tmp_path = os.path.join(tmpdirname, "dag.png")
dot.write_png(tmp_path)
with Image.open(tmp_path) as test_image:
image = test_image.copy()
os.remove(tmp_path)
return image
else:
if not HAS_PIL:
raise MissingOptionalLibraryError(
libname="pillow",
name="dag_drawer",
pip_install="pip install pillow",
)
with tempfile.TemporaryDirectory() as tmpdirname:
tmp_path = os.path.join(tmpdirname, "dag.png")
dot.write_png(tmp_path)
image = Image.open(tmp_path)
image.show()
os.remove(tmp_path)
return None