Merge pull request #5 from Qiskit/main

Fix measure with condition display in mpl and latex drawers (Qiskit#6822)

qiskit/visualization/latex.py

@@ -22,7 +22,6 @@
 from qiskit.circuit.library.standard_gates import SwapGate, XGate, ZGate, RZZGate, U1Gate, PhaseGate
 from qiskit.circuit.measure import Measure
 from qiskit.visualization.qcstyle import load_style
-from qiskit.visualization import exceptions
 from qiskit.circuit.tools.pi_check import pi_check
 from .utils import get_gate_ctrl_text, get_param_str, generate_latex_label
 
@@ -394,6 +393,10 @@ def _build_latex_array(self):
             for node in layer:
                 op = node.op
                 num_cols_op = 1
+                wire_list = [self.img_regs[qarg] for qarg in node.qargs]
+                if op.condition:
+                    self._add_condition(op, wire_list, column)
+
                 if isinstance(op, Measure):
                     self._build_measure(node, column)
 
@@ -404,15 +407,11 @@ def _build_latex_array(self):
                     gate_text, _, _ = get_gate_ctrl_text(op, "latex", style=self._style)
                     gate_text += get_param_str(op, "latex", ndigits=4)
                     gate_text = generate_latex_label(gate_text)
-                    wire_list = [self.img_regs[qarg] for qarg in node.qargs]
                     if node.cargs:
                         cwire_list = [self.img_regs[carg] for carg in node.cargs]
                     else:
                         cwire_list = []
 
-                    if op.condition:
-                        self._add_condition(op, wire_list, column)
-
                     if len(wire_list) == 1 and not node.cargs:
                         self._latex[wire_list[0]][column] = "\\gate{%s}" % gate_text
 
@@ -531,10 +530,8 @@ def _build_symmetric_gate(self, op, gate_text, wire_list, col):
 
     def _build_measure(self, node, col):
         """Build a meter and the lines to the creg"""
-        if node.op.condition:
-            raise exceptions.VisualizationError("If controlled measures currently not supported.")
-
         wire1 = self.img_regs[node.qargs[0]]
+        self._latex[wire1][col] = "\\meter"
         if self.cregbundle:
             wire2 = len(self.qubit_list)
             cregindex = self.img_regs[node.cargs[0]] - wire2
@@ -544,17 +541,15 @@ def _build_measure(self, node, col):
                     wire2 += 1
                 else:
                     break
-        else:
-            wire2 = self.img_regs[node.cargs[0]]
-
-        self._latex[wire1][col] = "\\meter"
-        if self.cregbundle:
-            self._latex[wire2][col] = "\\dstick{_{_{%s}}} \\cw \\cwx[-%s]" % (
+            cond_offset = 1.5 if node.op.condition else 0.0
+            self._latex[wire2][col] = "\\dstick{_{_{\\hspace{%sem}%s}}} \\cw \\ar @{<=} [-%s,0]" % (
+                cond_offset,
                 str(cregindex),
                 str(wire2 - wire1),
             )
         else:
-            self._latex[wire2][col] = "\\control \\cw \\cwx[-" + str(wire2 - wire1) + "]"
+            wire2 = self.img_regs[node.cargs[0]]
+            self._latex[wire2][col] = "\\cw \\ar @{<=} [-" + str(wire2 - wire1) + ",0]"
 
     def _build_barrier(self, node, col):
         """Build a partial or full barrier if plot_barriers set"""
@@ -612,18 +607,29 @@ def _add_condition(self, op, wire_list, col):
             cwire += 1
 
         gap = cwire - max(wire_list)
+        meas_offset = -0.3 if isinstance(op, Measure) else 0.0
         if self.cregbundle:
-            # Print the condition value at the bottom
-            self._latex[cwire][col] = "\\dstick{_{_{=%s}}} \\cw \\cwx[-%s]" % (
-                str(op.condition[1]),
+            # Print the condition value at the bottom and put bullet on creg line
+            self._latex[cwire][col] = "\\control \\cw^(%s){^{\\mathtt{%s}}} \\cwx[-%s]" % (
+                meas_offset,
+                str(hex(op.condition[1])),
                 str(gap),
             )
         else:
             # Add the open and closed buttons to indicate the condition value
-            for i in range(creg_size):
+            for i in range(creg_size - 1):
                 control = "\\control" if if_value[i] == "1" else "\\controlo"
                 self._latex[cwire + i][col] = f"{control} \\cw \\cwx[-" + str(gap) + "]"
                 gap = 1
+            # Add (hex condition value) below the last cwire
+            control = "\\control" if if_value[creg_size - 1] == "1" else "\\controlo"
+            self._latex[creg_size + cwire - 1][col] = (
+                f"{control}" + " \\cw^(%s){^{\\mathtt{%s}}} \\cwx[-%s]"
+            ) % (
+                meas_offset,
+                str(hex(op.condition[1])),
+                str(gap),
+            )
 
     def _truncate_float(self, matchobj, ndigits=4):
         """Truncate long floats."""

qiskit/visualization/matplotlib.py

@@ -903,6 +903,8 @@ def _condition(self, node, cond_xy):
                 v_ind += 1
         clbit_b = min(xy_plot, key=lambda xy: xy[1])
         xpos, ypos = clbit_b
+        if isinstance(node.op, Measure):
+            xpos += 0.3
         self._ax.text(
             xpos,
             ypos - 0.3 * HIG,

qiskit/visualization/text.py

@@ -890,11 +890,6 @@ def draw_wires(self, wires):
 
         return lines
 
-    @staticmethod
-    def label_for_conditional(node):
-        """Creates the label for a conditional instruction."""
-        return "= %s" % node.op.condition[1]
-
     @staticmethod
     def special_label(node):
         """Some instructions have special labels"""
@@ -1384,7 +1379,7 @@ def set_cl_multibox(self, creg, val, top_connect="┴"):
                 label = f"{bit_reg.name}_{bit_index} {label_bool}"
                 self.set_clbit(creg, BoxOnClWire(label=label, top_connect=top_connect))
             else:
-                label = "= %s" % val
+                label = "%s" % str(hex(val))
                 self.set_clbit(creg[0], BoxOnClWire(label=label, top_connect=top_connect))
         else:
             if isinstance(creg, Clbit):
@@ -1410,7 +1405,7 @@ def set_cond_bullets(self, val, clbits):
         for i, bit in enumerate(clbits):
             bot_connect = " "
             if bit == clbits[-1]:
-                bot_connect = "=%s" % str(int(val, 2))
+                bot_connect = "%s" % str(hex(int(val, 2)))
             if vlist[i] == "1":
                 self.set_clbit(bit, ClBullet(top_connect="║", bot_connect=bot_connect))
             elif vlist[i] == "0":

releasenotes/notes/fix-display-measure-condition-139ddbb8c7ae4071.yaml

@@ -0,0 +1,17 @@
+---
+fixes:
+  - |
+    Fixed an issue with the :func:`~qiskit.visualization.circuit_drawer`
+    function and :meth:`~qiskit.circuit.QuantumCircuit.draw` method of
+    :class:`~qiskit.circuit.QuantumCircuit`. When displaying a ``measure``
+    instruction containing a classical ``condition`` using the ``mpl`` or
+    ``latex`` options, the ``condition`` information would sometimes
+    overwrite the ``measure`` display.
+fixes:
+  - |
+    Fixed an issue with the :func:`~qiskit.visualization.circuit_drawer`
+    function and :meth:`~qiskit.circuit.QuantumCircuit.draw` method of
+    :class:`~qiskit.circuit.QuantumCircuit`. The ``mpl`` drawer used hex
+    notation to display the ``condition`` value, whereas the ``text`` and
+    ``latex`` drawers used decimal notation. Now all three drawers use
+    hex notation.

test/ipynb/mpl/circuit/test_circuit_matplotlib_drawer.py

@@ -625,8 +625,9 @@ def test_user_ax_subplot(self):
 
         fig = plt.figure(1, figsize=(6, 4))
         fig.patch.set_facecolor("white")
-        fig.add_subplot(1, 2, 1)
+        ax1 = fig.add_subplot(1, 2, 1)
         ax2 = fig.add_subplot(1, 2, 2)
+        ax1.plot([1, 2, 3])
 
         circuit = QuantumCircuit(4)
         circuit.h(0)
@@ -646,6 +647,20 @@ def test_figwidth(self):
         circuit.x(2)
         self.circuit_drawer(circuit, style={"figwidth": 5}, filename="figwidth.png")
 
+    def test_measures_with_conditions(self):
+        """Test that a measure containing a condition displays"""
+        qr = QuantumRegister(2, "qr")
+        cr1 = ClassicalRegister(2, "cr1")
+        cr2 = ClassicalRegister(2, "cr2")
+        circuit = QuantumCircuit(qr, cr1, cr2)
+        circuit.h(0)
+        circuit.h(1)
+        circuit.measure(0, cr1[1])
+        circuit.measure(1, cr2[0]).c_if(cr1, 1)
+        circuit.h(0).c_if(cr2, 3)
+        self.circuit_drawer(circuit, cregbundle=False, filename="measure_cond_false.png")
+        self.circuit_drawer(circuit, cregbundle=True, filename="measure_cond_true.png")
+
 
 if __name__ == "__main__":
     unittest.main(verbosity=1)

test/python/visualization/references/test_latex_4597.tex

@@ -9,6 +9,6 @@
 	 	\nghost{ {q}_{0} :  } & \lstick{ {q}_{0} :  } & \qw & \qw & \qw & \qw\\
 	 	\nghost{ {q}_{1} :  } & \lstick{ {q}_{1} :  } & \qw & \qw & \qw & \qw\\
 	 	\nghost{ {q}_{2} :  } & \lstick{ {q}_{2} :  } & \qw & \gate{\mathrm{X}} & \qw & \qw\\
-	 	\nghost{c:} & \lstick{c:} & \lstick{/_{_{3}}} \cw & \dstick{_{_{=2}}} \cw \cwx[-1] & \cw & \cw\\
+	 	\nghost{c:} & \lstick{c:} & \lstick{/_{_{3}}} \cw & \control \cw^(0.0){^{\mathtt{0x2}}} \cwx[-1] & \cw & \cw\\
 \\ }}
 \end{document}

test/python/visualization/references/test_latex_conditional.tex

@@ -8,6 +8,6 @@
 \Qcircuit @C=1.0em @R=0.2em @!R { \\
 	 	\nghost{ {q}_{0} :  } & \lstick{ {q}_{0} :  } & \gate{\mathrm{H}} & \meter & \qw & \gate{\mathrm{H}} & \qw & \qw\\
 	 	\nghost{ {q}_{1} :  } & \lstick{ {q}_{1} :  } & \gate{\mathrm{H}} & \qw & \meter & \qw & \qw & \qw\\
-	 	\nghost{c:} & \lstick{c:} & \lstick{/_{_{2}}} \cw & \dstick{_{_{0}}} \cw \cwx[-2] & \dstick{_{_{1}}} \cw \cwx[-1] & \dstick{_{_{=2}}} \cw \cwx[-2] & \cw & \cw\\
+	 	\nghost{c:} & \lstick{c:} & \lstick{/_{_{2}}} \cw & \dstick{_{_{\hspace{0.0em}0}}} \cw \ar @{<=} [-2,0] & \dstick{_{_{\hspace{0.0em}1}}} \cw \ar @{<=} [-1,0] & \control \cw^(0.0){^{\mathtt{0x2}}} \cwx[-2] & \cw & \cw\\
 \\ }}
 \end{document}

test/python/visualization/references/test_latex_meas_cond_false.tex

@@ -0,0 +1,16 @@
+\documentclass[border=2px]{standalone}
+
+\usepackage[braket, qm]{qcircuit}
+\usepackage{graphicx}
+
+\begin{document}
+\scalebox{1.0}{
+\Qcircuit @C=1.0em @R=0.2em @!R { \\
+	 	\nghost{ {qr}_{0} :  } & \lstick{ {qr}_{0} :  } & \gate{\mathrm{H}} & \meter & \qw & \gate{\mathrm{H}} & \qw & \qw\\
+	 	\nghost{ {qr}_{1} :  } & \lstick{ {qr}_{1} :  } & \gate{\mathrm{H}} & \qw & \meter & \qw & \qw & \qw\\
+	 	\nghost{cr1_{0}:} & \lstick{cr1_{0}:} & \cw & \cw & \control \cw \cwx[-1] & \cw & \cw & \cw\\
+	 	\nghost{cr1_{1}:} & \lstick{cr1_{1}:} & \cw & \cw \ar @{<=} [-3,0] & \controlo \cw^(-0.3){^{\mathtt{0x1}}} \cwx[-1] & \cw & \cw & \cw\\
+	 	\nghost{cr2_{0}:} & \lstick{cr2_{0}:} & \cw & \cw & \cw \ar @{<=} [-3,0] & \control \cw \cwx[-4] & \cw & \cw\\
+	 	\nghost{cr2_{1}:} & \lstick{cr2_{1}:} & \cw & \cw & \cw & \control \cw^(0.0){^{\mathtt{0x3}}} \cwx[-1] & \cw & \cw\\
+\\ }}
+\end{document}

test/python/visualization/references/test_latex_meas_cond_true.tex

@@ -0,0 +1,14 @@
+\documentclass[border=2px]{standalone}
+
+\usepackage[braket, qm]{qcircuit}
+\usepackage{graphicx}
+
+\begin{document}
+\scalebox{1.0}{
+\Qcircuit @C=1.0em @R=0.2em @!R { \\
+	 	\nghost{ {qr}_{0} :  } & \lstick{ {qr}_{0} :  } & \gate{\mathrm{H}} & \meter & \qw & \gate{\mathrm{H}} & \qw & \qw\\
+	 	\nghost{ {qr}_{1} :  } & \lstick{ {qr}_{1} :  } & \gate{\mathrm{H}} & \qw & \meter & \qw & \qw & \qw\\
+	 	\nghost{cr1:} & \lstick{cr1:} & \lstick{/_{_{2}}} \cw & \dstick{_{_{\hspace{0.0em}1}}} \cw \ar @{<=} [-2,0] & \control \cw^(-0.3){^{\mathtt{0x1}}} \cwx[-1] & \cw & \cw & \cw\\
+	 	\nghost{cr2:} & \lstick{cr2:} & \lstick{/_{_{2}}} \cw & \cw & \dstick{_{_{\hspace{1.5em}0}}} \cw \ar @{<=} [-2,0] & \control \cw^(0.0){^{\mathtt{0x3}}} \cwx[-3] & \cw & \cw\\
+\\ }}
+\end{document}

test/python/visualization/references/test_latex_meas_condition.tex

@@ -8,6 +8,6 @@
 \Qcircuit @C=1.0em @R=0.2em @!R { \\
 	 	\nghost{ {qr}_{0} :  } & \lstick{ {qr}_{0} :  } & \gate{\mathrm{H}} & \meter & \qw & \qw & \qw\\
 	 	\nghost{ {qr}_{1} :  } & \lstick{ {qr}_{1} :  } & \qw & \qw & \gate{\mathrm{H}} & \qw & \qw\\
-	 	\nghost{cr:} & \lstick{cr:} & \lstick{/_{_{2}}} \cw & \dstick{_{_{0}}} \cw \cwx[-2] & \dstick{_{_{=1}}} \cw \cwx[-1] & \cw & \cw\\
+	 	\nghost{cr:} & \lstick{cr:} & \lstick{/_{_{2}}} \cw & \dstick{_{_{\hspace{0.0em}0}}} \cw \ar @{<=} [-2,0] & \control \cw^(0.0){^{\mathtt{0x1}}} \cwx[-1] & \cw & \cw\\
 \\ }}
 \end{document}

test/python/visualization/references/test_latex_teleport.tex

@@ -9,6 +9,6 @@
 	 	\nghost{ {q}_{0} :  } & \lstick{ {q}_{0} :  } & \gate{\mathrm{U}\,(\mathrm{0.3,0.2,0.1})} & \qw \barrier[0em]{2} & \qw & \ctrl{1} & \gate{\mathrm{H}} & \meter & \qw & \qw & \qw & \qw & \qw\\
 	 	\nghost{ {q}_{1} :  } & \lstick{ {q}_{1} :  } & \gate{\mathrm{H}} & \ctrl{1} & \qw & \targ & \meter & \qw & \qw & \qw & \qw & \qw & \qw\\
 	 	\nghost{ {q}_{2} :  } & \lstick{ {q}_{2} :  } & \qw & \targ & \qw & \qw & \qw & \qw & \gate{\mathrm{Z}} & \gate{\mathrm{X}} & \meter & \qw & \qw\\
-	 	\nghost{c:} & \lstick{c:} & \lstick{/_{_{3}}} \cw & \cw & \cw & \cw & \dstick{_{_{1}}} \cw \cwx[-2] & \dstick{_{_{0}}} \cw \cwx[-3] & \dstick{_{_{=1}}} \cw \cwx[-1] & \dstick{_{_{=2}}} \cw \cwx[-1] & \dstick{_{_{2}}} \cw \cwx[-1] & \cw & \cw\\
+	 	\nghost{c:} & \lstick{c:} & \lstick{/_{_{3}}} \cw & \cw & \cw & \cw & \dstick{_{_{\hspace{0.0em}1}}} \cw \ar @{<=} [-2,0] & \dstick{_{_{\hspace{0.0em}0}}} \cw \ar @{<=} [-3,0] & \control \cw^(0.0){^{\mathtt{0x1}}} \cwx[-1] & \control \cw^(0.0){^{\mathtt{0x2}}} \cwx[-1] & \dstick{_{_{\hspace{0.0em}2}}} \cw \ar @{<=} [-1,0] & \cw & \cw\\
 \\ }}
 \end{document}

test/python/visualization/test_circuit_latex.py

@@ -548,6 +548,24 @@ def test_inst_with_cbits(self):
 
         self.assertEqualToReference(filename)
 
+    def test_measures_with_conditions(self):
+        """Test that a measure containing a condition displays"""
+        filename1 = self._get_resource_path("test_latex_meas_cond_false.tex")
+        filename2 = self._get_resource_path("test_latex_meas_cond_true.tex")
+        qr = QuantumRegister(2, "qr")
+        cr1 = ClassicalRegister(2, "cr1")
+        cr2 = ClassicalRegister(2, "cr2")
+        circuit = QuantumCircuit(qr, cr1, cr2)
+        circuit.h(0)
+        circuit.h(1)
+        circuit.measure(0, cr1[1])
+        circuit.measure(1, cr2[0]).c_if(cr1, 1)
+        circuit.h(0).c_if(cr2, 3)
+        circuit_drawer(circuit, cregbundle=False, filename=filename1, output="latex_source")
+        circuit_drawer(circuit, cregbundle=True, filename=filename2, output="latex_source")
+        self.assertEqualToReference(filename1)
+        self.assertEqualToReference(filename2)
+
 
 if __name__ == "__main__":
     unittest.main(verbosity=2)