如何注释堆积条形图的每一段 [英] How to annotate each segment of a stacked bar chart

问题描述

我一直试图用其值来注释堆积条形图的每个子数量，如上图所示(值不准确，只是一个示例).

  df.iloc [1:].T.plot(种类='bar'，堆叠= True)plt.show()

我使用的数据框:

链接的帖子有点类似于我的问题，但是我不理解该答案中给出的代码，也没有给出任何解释.

注释资源 - 来自 matplotlib v3.4.2

• I've been trying to annotate each sub-amount of a stacked bar chart with its values like the picture shown above (values not accurate, just an example).

  df.iloc[1:].T.plot(kind='bar', stacked=True)
  plt.show()
  

  Data frame that I used:

  The linked post is somewhat similar to my question but I do not understand the code given in that answer nor were there any explanations given.

  Annotating Values in Stacked Bar Chart Matplotlib

  解决方案

  Imports and DataFrame

  import pandas as pd
  import matplotlib.pyplot as plt
  
  data = {'var': ['TR', 'AC', 'F&B'], '2019 1Q': [6600, 1256, 588], '2019 2Q': [6566, 1309, 586], '2019 3Q': [7383, 1525, 673]}
  df = pd.DataFrame(data)
  df.set_index('var', inplace=True)
  
  # display(df)
       2019 1Q  2019 2Q  2019 3Q
  var                           
  TR      6600     6566     7383
  AC      1256     1309     1525
  F&B      588      586      673
  

  Update as of matplotlib v3.4.2

  • Use matplotlib.pyplot.bar_label
  • See the matplotlib: Bar Label Demo page for additional formatting options.
  • Tested with pandas v1.2.4, which is using matplotlib as the plot engine.

  ax = df.T.plot.bar(stacked=True, figsize=(6, 5), rot=0)
  
  for c in ax.containers:
      ax.bar_label(c, label_type='center')
      
  ax.legend(title='Categories', bbox_to_anchor=(1.05, 1), loc='upper left')
  

  Annotation Resources - from matplotlib v3.4.2

  • Adding value labels on a matplotlib bar chart
  • Stacked Bar Chart with Centered Labels
  • How to plot and annotate multiple data columns in a seaborn barplot
  • How to annotate a seaborn barplot with the aggregated value
  • stack bar plot in matplotlib and add label to each section
  • How to add multiple annotations to a barplot
  • How to plot and annotate a grouped bar chart

  Original Answer - prior to matplotlib v3.4.2

  • Transpose the dataframe and then use pandas.DataFrame.plot.bar with stacked=True.
  • An ndarray is returned with one matplotlib.axes.Axes per column with subplots=True.
    • In the case of this figure, ax.patches contains 9 matplotlib.patches.Rectangle objects, one for each segment of each bar.
      • By using the associated methods for this object, the height, width, x, and y locations can be extracted, and used to annotate the rectangles.
  • The difference this question has from How to annotate a stacked bar chart with word count and column name? is the other question needs to extract and use alternate text for labels, and this dataframe needed to be transposed.

  ax = df.T.plot.bar(stacked=True)
  plt.legend(title='Categories', bbox_to_anchor=(1.05, 1), loc='upper left')
  
  for i, rect in enumerate(ax.patches):
      # Find where everything is located
      height = rect.get_height()
      width = rect.get_width()
      x = rect.get_x()
      y = rect.get_y()
  
      # The height of the bar is the count value and can used as the label
      label_text = f'{height:.0f}'
  
      label_x = x + width / 2
      label_y = y + height / 2
  
      # don't include label if it's equivalently 0
      if height > 0.001:
          ax.text(label_x, label_y, label_text, ha='center', va='center', fontsize=8)
  

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