为什么我的 Pandas 绘图功能会在彼此之上绘制独立的数据集？

Question

我有一个电话价格数据集，在列表中，我想使用 Pandas 和 plot 方法为每个模型绘制一个直方图。

当我尝试使用函数执行此操作时，直方图会被绘制在彼此之上。所以第一个图是正确的，但是下一个有两个直方图，然后下一个有所有 3 个模型图，依此类推。

import pandas as pd
import matplotlib.pyplot as plt

def printPlot(plotlist, model):

    d = pd.DataFrame(plotlist)

    d.columns = ['Model','GB','Condition','Price']

    lowestquantile = d["Price"].quantile(0.2)

    d = d[d["Price"] > lowestquantile]

    d.Price.plot(kind='hist')

    plotfile = model+".png"

    plt.savefig("./plots/"+plotfile)

    return

testplot = [[['iPhone 11', ' 64 GB', 'N/A', 5500], ['iPhone 11', ' 256 GB', 'Perfekt', 6500], ['iPhone 11', ' 64 GB', 'Perfekt', 5100], ['iPhone 11', ' 128 GB', 'Perfekt', 6200], ['iPhone 11', ' 64 GB', 'Perfekt', 5700], ['iPhone 11', ' 128 GB', 'Perfekt', 5750], ['iPhone 11', ' 128 GB', 'God', 1111], ['iPhone 11', ' 256 GB', 'Perfekt', 5700], ['iPhone 11', ' 64 GB', 'Perfekt', 5800], ['iPhone 11', ' 64 GB', 'Perfekt', 5200], ['iPhone 11', ' 8 GB', 'N/A', 10], ['iPhone 11', ' 256 GB', 'Perfekt', 4500], ['iPhone 11', ' 256 GB', 'Perfekt', 7000], ['iPhone 11', ' 64 GB', 'Perfekt', 5299], ['iPhone 11', ' 64 GB', 'Perfekt', 6000], ['iPhone 11', ' 256 GB', 'N/A', 50], ['iPhone 11', ' 64 GB', 'Perfekt', 250], ['iPhone 11', ' 128 GB', 'Perfekt', 200], ['iPhone 11', ' 128 GB', 'Perfekt', 6200], ['iPhone 11', ' 128 GB', 'N/A', 6350], ['iPhone 11', ' 64 GB', 'Perfekt', 69], ['iPhone 11', ' 512 GB', 'Perfekt', 100]],[['iPhone XS Max', ' 256 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6750], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5399], ['iPhone XS Max', ' 64 GB', 'God', 3300], ['iPhone XS Max', ' 64 GB', 'Perfekt', 4800], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6666], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6500], ['iPhone XS Max', ' 64 GB', 'N/A', 5500], ['iPhone XS Max', ' 256 GB', 'God', 4700], ['iPhone XS Max', ' 64 GB', 'God', 5500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6450], ['iPhone XS Max', ' 512 GB', 'N/A', 9000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5700], ['iPhone XS Max', ' 512 GB', 'Perfekt', 5345], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6999], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5500], ['iPhone XS Max', ' 512 GB', 'N/A', 5499], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6500], ['iPhone XS Max', ' 64 GB', 'Rimelig', 3000], ['iPhone XS Max', ' 256 GB', 'N/A', 4700], ['iPhone XS Max', ' 256 GB', 'N/A', 7500], ['iPhone XS Max', ' 256 GB', 'God', 5500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 4000], ['iPhone XS Max', ' 64 GB', 'N/A', 4499], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5000], ['iPhone XS Max', ' 64 GB', 'N/A', 4000], ['iPhone XS Max', ' 512 GB', 'Perfekt', 7000], ['iPhone XS Max', ' 64 GB', 'God', 200], ['iPhone XS Max', ' 256 GB', 'God', 5000], ['iPhone XS Max', ' 64 GB', 'Perfekt', 4400], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6500], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 64 GB', 'N/A', 5000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 512 GB', 'Perfekt', 5000], ['iPhone XS Max', ' 256 GB', 'God', 4500], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5000], ['iPhone XS Max', ' 512 GB', 'God', 6500], ['iPhone XS Max', ' 512 GB', 'N/A', 6500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6500], ['iPhone XS Max', ' 64 GB', 'God', 3799], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5399], ['iPhone XS Max', ' 64 GB', 'N/A', 4599], ['iPhone XS Max', ' 64 GB', 'God', 6000], ['iPhone XS Max', ' 8 GB', 'Perfekt', 130], ['iPhone XS Max', ' 8 GB', 'Perfekt', 130], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6499], ['iPhone XS Max', ' 64 GB', 'Perfekt', 4599], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5500], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 8 GB', 'Perfekt', 850], ['iPhone XS Max', ' 256 GB', 'God', 5000], ['iPhone XS Max', ' 256 GB', 'God', 6000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5500], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6499], ['iPhone XS Max', ' 512 GB', 'Perfekt', 5500], ['iPhone XS Max', ' 64 GB', 'God', 5000], ['iPhone XS Max', ' 64 GB', 'God', 4700], ['iPhone XS Max', ' 64 GB', 'God', 4900], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5000], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6200], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5500], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 4499], ['iPhone XS Max', ' 64 GB', 'God', 4500], ['iPhone XS Max', ' 64 GB', 'Perfekt', 250], ['iPhone XS Max', ' 256 GB', 'Perfekt', 7000], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5900], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 150], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6750], ['iPhone XS Max', ' 64 GB', 'God', 4000], ['iPhone XS Max', ' 256 GB', 'God', 6000], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 512 GB', 'N/A', 7000], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5000], ['iPhone XS Max', ' 64 GB', 'Perfekt', 4999], ['iPhone XS Max', ' 256 GB', 'God', 100], ['iPhone XS Max', ' 256 GB', 'God', 5000], ['iPhone XS Max', ' 256 GB', 'God', 5000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6199], ['iPhone XS Max', ' 512 GB', 'Perfekt', 7500], ['iPhone XS Max', ' 64 GB', 'N/A', 6000], ['iPhone XS Max', ' 64 GB', 'Perfekt', 4400], ['iPhone XS Max', ' 64 GB', 'Perfekt', 4500], ['iPhone XS Max', ' 512 GB', 'God', 6500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5400], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5000], ['iPhone XS Max', ' 64 GB', 'God', 4000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5800], ['iPhone XS Max', ' 64 GB', 'Perfekt', 4800], ['iPhone XS Max', ' 512 GB', 'N/A', 250], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 4700], ['iPhone XS Max', ' 512 GB', 'Perfekt', 5800], ['iPhone XS Max', ' 512 GB', 'Perfekt', 7999], ['iPhone XS Max', ' 64 GB', 'N/A', 5300], ['iPhone XS Max', ' 256 GB', 'Rimelig', 5500], ['iPhone XS Max', ' 64 GB', 'Perfekt', 4995], ['iPhone XS Max', ' 256 GB', 'God', 4800], ['iPhone XS Max', ' 64 GB', 'Perfekt', 4200], ['iPhone XS Max', ' 512 GB', 'Perfekt', 7000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6499], ['iPhone XS Max', ' 256 GB', 'Perfekt', 4999], ['iPhone XS Max', ' 64 GB', 'N/A', 4599], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5999], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6999], ['iPhone XS Max', ' 256 GB', 'God', 4200], ['iPhone XS Max', ' 64 GB', 'God', 4300], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6499], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6900], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 64 GB', 'Rimelig', 4500], ['iPhone XS Max', ' 64 GB', 'Perfekt', 5500], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6000], ['iPhone XS Max', ' 256 GB', 'God', 280], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6900], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5800], ['iPhone XS Max', ' 8 GB', 'Perfekt', 150], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6999], ['iPhone XS Max', ' 64 GB', 'Perfekt', 4800], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6999], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6250], ['iPhone XS Max', ' 256 GB', 'Perfekt', 7000], ['iPhone XS Max', ' 256 GB', 'God', 4999], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6999], ['iPhone XS Max', ' 256 GB', 'Perfekt', 6999], ['iPhone XS Max', ' 512 GB', 'Perfekt', 50], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5700], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5000], ['iPhone XS Max', ' 512 GB', 'Perfekt', 7000], ['iPhone XS Max', ' 64 GB', 'Perfekt', 6200], ['iPhone XS Max', ' 256 GB', 'Perfekt', 7000], ['iPhone XS Max', ' 512 GB', 'Perfekt', 7500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 7000], ['iPhone XS Max', ' 128 GB', 'Perfekt', 110], ['iPhone XS Max', ' 256 GB', 'Perfekt', 7100], ['iPhone XS Max', ' 256 GB', 'Perfekt', 99], ['iPhone XS Max', ' 256 GB', 'Perfekt', 7400], ['iPhone XS Max', ' 128 GB', 'Perfekt', 99], ['iPhone XS Max', ' 256 GB', 'Perfekt', 7300], ['iPhone XS Max', ' 512 GB', 'Perfekt', 6750], ['iPhone XS Max', ' 64 GB', 'God', 4500], ['iPhone XS Max', ' 256 GB', 'Perfekt', 5000]]]

for plotlist in testplot:

    printPlot(plotlist,plotlist[0][0])

Answer 1

为避免这种行为，只需在 printPlot() 函数中的 return 之前再添加一行 plt.clf()。代码将如下所示：

def printPlot(plotlist, model):
    d = pd.DataFrame(plotlist)
    d.columns = ['Model','GB','Condition','Price']
    lowestquantile = d["Price"].quantile(0.2)
    d = d[d["Price"] > lowestquantile]
    d.Price.plot(kind='hist')
    plotfile = model+".png"
    plt.savefig("./plots/" + plotfile)

    plt.clf() # <-- this row was missing (!)

    return