[Python Tutorial] Drawing a Waterfall Chart

Waterfall chart is a chart type originally created by McKinsey Consulting Company. It is called Waterfall Plot because it looks like a waterfall. This kind of chart uses a combination of absolute value and relative value, and is mostly suitable for expressing the quantitative relationship between multiple specific values. This article briefly introduces how to draw this graph using Python.

The command is as follows

1）导入程序包
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
from matplotlib.ticker import FuncFormatter
2）导入及清理数据
def money(x, pos):
return "${:,.0f}".format(x)
formatter = FuncFormatter(money)
index = ['sales','returns','credit fees','rebates','late charges','shipping']
data = {'amount': [350000,-30000,-7500,-25000,95000,-7000]}
trans = pd.DataFrame(data=data,index=index)
blank = trans.amount.cumsum().shift(1).fillna(0)
total = trans.sum().amount
trans.loc["net"]= total
blank.loc["net"] = total
step = blank.reset_index(drop=True).repeat(3).shift(-1)
step[1::3] = np.nan
blank.loc["net"] = 0
3）绘制图像
my_plot = trans.plot(kind='bar', stacked=True, bottom=blank,legend=None, figsize=(10, 5), title="2014 Sales Waterfall")
my_plot.plot(step.index, step.values,'k')
my_plot.set_xlabel("Transaction Types")
my_plot.yaxis.set_major_formatter(formatter)
y_height = trans.amount.cumsum().shift(1).fillna(0)
max = trans.max()
neg_offset = max / 25
pos_offset = max / 50
plot_offset = int(max / 15)
loop = 0
for index, row in trans.iterrows():
if row['amount'] == total:
y = y_height[loop]
else:
y = y_height[loop] + row['amount']
if row['amount'] > 0:
y += pos_offset
else:
y -= neg_offset
my_plot.annotate("{:,.0f}".format(row['amount']),(loop,y),ha="center")
loop+=1
my_plot.set_ylim(0,blank.max()+int(plot_offset))
my_plot.set_xticklabels(trans.index,rotation=0)
my_plot.get_figure().savefig("waterfall.png",dpi=200,bbox_inches='tight')

The output is as follows

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