""" ================ 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. # [, [, ]] 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()