如何在分组条形图上方显示百分比

问题描述

以下是 pandas 数据框和由此生成的条形图:

colors_list = ['#5cb85c','#5bc0de','#d9534f']result.plot(kind='bar',figsize=(15,4),width = 0.8,color = colors_list,edgecolor=None)plt.legend(labels=result.columns,fontsize=14)plt.title("受访者对数据科学领域感兴趣的百分比",fontsize= 16)plt.xticks(字体大小=14)对于 plt.gca().spines.values() 中的脊椎:脊柱.set_visible(假)plt.yticks([])

我需要在相应栏上方显示各个主题的每个兴趣类别的百分比.我可以创建一个包含百分比的列表，但我不明白如何将它添加到相应栏的顶部.

解决方案

尝试将以下 for 循环添加到您的代码中:

ax = result.plot(kind='bar', figsize=(15,4), width=0.8, color=colors_list, edgecolor=None)对于 ax.patches 中的 p:宽度 = p.get_width()高度 = p.get_height()x, y = p.get_xy()ax.annotate(f'{height}', (x + width/2, y + height*1.02), ha='center')

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说明

通常，您使用

The following are the pandas dataframe and the bar chart generated from it:

colors_list = ['#5cb85c','#5bc0de','#d9534f']
result.plot(kind='bar',figsize=(15,4),width = 0.8,color = colors_list,edgecolor=None)
plt.legend(labels=result.columns,fontsize= 14)
plt.title("Percentage of Respondents' Interest in Data Science Areas",fontsize= 16)

plt.xticks(fontsize=14)
for spine in plt.gca().spines.values():
    spine.set_visible(False)
plt.yticks([])

I need to display the percentages of each interest category for the respective subject above their corresponding bar. I can create a list with the percentages, but I don't understand how to add it on top of the corresponding bar.

解决方案

Try adding the following for loop to your code:

ax = result.plot(kind='bar', figsize=(15,4), width=0.8, color=colors_list, edgecolor=None)

for p in ax.patches:
    width = p.get_width()
    height = p.get_height()
    x, y = p.get_xy() 
    ax.annotate(f'{height}', (x + width/2, y + height*1.02), ha='center')

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Explanation

In general, you use Axes.annotate to add annotations to your plots.
This method takes the text value of the annotation and the xy coords on which to place the annotation.

In a barplot, each "bar" is represented by a patch.Rectangle and each of these rectangles has the attributes width, height and the xy coords of the lower left corner of the rectangle, all of which can be obtained with the methods patch.get_width, patch.get_height and patch.get_xy respectively.

Putting this all together, the solution is to loop through each patch in your Axes, and set the annotation text to be the height of that patch, with an appropriate xy position that's just above the centre of the patch - calculated from it's height, width and xy coords.

---

For your specific need to annotate with the percentages, I would first normalize your DataFrame and plot that instead.

colors_list = ['#5cb85c','#5bc0de','#d9534f']

# Normalize result
result_pct = result.div(result.sum(1), axis=0)

ax = result_pct.plot(kind='bar',figsize=(15,4),width = 0.8,color = colors_list,edgecolor=None)
plt.legend(labels=result.columns,fontsize= 14)
plt.title("Percentage of Respondents' Interest in Data Science Areas",fontsize= 16)

plt.xticks(fontsize=14)
for spine in plt.gca().spines.values():
    spine.set_visible(False)
plt.yticks([])

# Add this loop to add the annotations
for p in ax.patches:
    width = p.get_width()
    height = p.get_height()
    x, y = p.get_xy() 
    ax.annotate(f'{height:.0%}', (x + width/2, y + height*1.02), ha='center')