matplotlib · timhoffm · Jun 6, 2023 · Jun 4, 2023 · Jun 5, 2023 · Jun 6, 2023
diff --git a/galleries/examples/specialty_plots/ishikawa_diagram.py b/galleries/examples/specialty_plots/ishikawa_diagram.py
@@ -0,0 +1,203 @@
+"""
+================
+Ishikawa Diagram
+================
+
+Ishikawa Diagrams, fishbone diagrams, herringbone diagrams, or cause-and-effect
+diagrams are used to identify problems in a system by showing how causes and
+effects are linked.
+Source: https://en.wikipedia.org/wiki/Ishikawa_diagram
+
+"""
+import matplotlib.pyplot as plt
+
+from matplotlib.patches import Polygon, Wedge
+
+# Create the fishbone diagram
+fig, ax = plt.subplots(figsize=(10, 6), layout='constrained')
+ax.set_xlim(-5, 5)
+ax.set_ylim(-5, 5)
+ax.axis('off')
+
+
+def problems(data: str,
+             problem_x: float, problem_y: float,
+             prob_angle_x: float, prob_angle_y: float):
+    """
+    Draw each problem section of the Ishikawa plot.
+
+    Parameters
+    ----------
+    data : str
+        The category name.
+    problem_x, problem_y : float, optional
+        The `X` and `Y` positions of the problem arrows (`Y` defaults to zero).
+    prob_angle_x, prob_angle_y : float, optional
+        The angle of the problem annotations. They are angled towards
+        the tail of the plot.
+
+    Returns
+    -------
+    None.
+
+    """
+    ax.annotate(str.upper(data), xy=(problem_x, problem_y),
+                xytext=(prob_angle_x, prob_angle_y),
+                fontsize='10',
+                color='white',
+                weight='bold',
+                xycoords='data',
+                verticalalignment='center',
+                horizontalalignment='center',
+                textcoords='offset fontsize',
+                arrowprops=dict(arrowstyle="->", facecolor='black'),
+                bbox=dict(boxstyle='square',
+                          facecolor='tab:blue',
+                          pad=0.8))
+
+
+def causes(data: list, cause_x: float, cause_y: float,
+           cause_xytext=(-9, -0.3), top: bool = True):
+    """
+    Place each cause to a position relative to the problems
+    annotations.
+
+    Parameters
+    ----------
+    data : indexable object
+        The input data. IndexError is
+        raised if more than six arguments are passed.
+    cause_x, cause_y : float
+        The `X` and `Y` position of the cause annotations.
+    cause_xytext : tuple, optional
+        Adjust to set the distance of the cause text from the problem
+        arrow in fontsize units.
+    top : bool
+
+    Returns
+    -------
+    None.
+
+    """
+    for index, cause in enumerate(data):
+        # First cause annotation is placed in the middle of the problems arrow
+        # and each subsequent cause is plotted above or below it in succession.
+
+        # [<x pos>, [<y pos top>, <y pos bottom>]]
+        coords = [[0, [0, 0]],
+                  [0.23, [0.5, -0.5]],
+                  [-0.46, [-1, 1]],
+                  [0.69, [1.5, -1.5]],
+                  [-0.92, [-2, 2]],
+                  [1.15, [2.5, -2.5]]]
+        if top:
+            cause_y += coords[index][1][0]
+        else:
+            cause_y += coords[index][1][1]
+        cause_x -= coords[index][0]
+
+        ax.annotate(cause, xy=(cause_x, cause_y),
+                    horizontalalignment='center',
+                    xytext=cause_xytext,
+                    fontsize='9',
+                    xycoords='data',
+                    textcoords='offset fontsize',
+                    arrowprops=dict(arrowstyle="->",
+                                    facecolor='black'))
+
+
+def draw_body(data: dict):
+    """
+    Place each section in its correct place by changing
+    the coordinates on each loop.
+
+    Parameters
+    ----------
+    data : dict
+        The input data (can be list or tuple). ValueError is
+        raised if more than six arguments are passed.
+
+    Returns
+    -------
+    None.
+
+    """
+    second_sections = []
+    third_sections = []
+    # Resize diagram to automatically scale in response to the number
+    # of problems in the input data.
+    if len(data) == 1 or len(data) == 2:
+        spine_length = (-2.1, 2)
+        head_pos = (2, 0)
+        tail_pos = ((-2.8, 0.8), (-2.8, -0.8), (-2.0, -0.01))
+        first_section = [1.6, 0.8]
+    elif len(data) == 3 or len(data) == 4:
+        spine_length = (-3.1, 3)
+        head_pos = (3, 0)
+        tail_pos = ((-3.8, 0.8), (-3.8, -0.8), (-3.0, -0.01))
+        first_section = [2.6, 1.8]
+        second_sections = [-0.4, -1.2]
+    else:  # len(data) == 5 or 6
+        spine_length = (-4.1, 4)
+        head_pos = (4, 0)
+        tail_pos = ((-4.8, 0.8), (-4.8, -0.8), (-4.0, -0.01))
+        first_section = [3.5, 2.7]
+        second_sections = [1, 0.2]
+        third_sections = [-1.5, -2.3]
+
+    # Change the coordinates of the annotations on each loop.
+    for index, problem in enumerate(data.values()):
+        top_row = True
+        cause_arrow_y = 1.7
+        if index % 2 != 0:  # Plot problems below the spine.
+            top_row = False
+            y_prob_angle = -16
+            cause_arrow_y = -1.7
+        else:  # Plot problems above the spine.
+            y_prob_angle = 16
+        # Plot the 3 sections in pairs along the main spine.
+        if index in (0, 1):
+            prob_arrow_x = first_section[0]
+            cause_arrow_x = first_section[1]
+        elif index in (2, 3):
+            prob_arrow_x = second_sections[0]
+            cause_arrow_x = second_sections[1]
+        else:
+            prob_arrow_x = third_sections[0]
+            cause_arrow_x = third_sections[1]
+        if index > 5:
+            raise ValueError(f'Maximum number of problems is 6, you have entered '
+                             f'{len(data)}')
+
+        # draw main spine
+        ax.plot(spine_length, [0, 0], color='tab:blue', linewidth=2)
+        # draw fish head
+        ax.text(head_pos[0] + 0.1, head_pos[1] - 0.05, 'PROBLEM', fontsize=10,
+                weight='bold', color='white')
+        semicircle = Wedge(head_pos, 1, 270, 90, fc='tab:blue')
+        ax.add_patch(semicircle)
+        # draw fishtail
+        triangle = Polygon(tail_pos, fc='tab:blue')
+        ax.add_patch(triangle)
+        # Pass each category name to the problems function as a string on each loop.
+        problems(list(data.keys())[index], prob_arrow_x, 0, -12, y_prob_angle)
+        # Start the cause function with the first annotation being plotted at
+        # the cause_arrow_x, cause_arrow_y coordinates.
+        causes(problem, cause_arrow_x, cause_arrow_y, top=top_row)
+
+
+# Input data
+categories = {
+    'Method': ['Time consumption', 'Cost', 'Procedures', 'Inefficient process',
+               'Sampling'],
+    'Machine': ['Faulty equipment', 'Compatibility'],
+    'Material': ['Poor-quality input', 'Raw materials', 'Supplier',
+                 'Shortage'],
+    'Measurement': ['Calibration', 'Performance', 'Wrong measurements'],
+    'Environment': ['Bad conditions'],
+    'People': ['Lack of training', 'Managers', 'Labor shortage',
+               'Procedures', 'Sales strategy']
+}
+
+draw_body(categories)
+plt.show()