pandas 条形图结合折线图显示了从 1970 年开始的时间轴

问题描述

我正在尝试绘制股票市场图表

时间序列与收盘价以及时间序列与交易量.

不知何故，x 轴显示了 1970 年的时间

以下是图和代码

代码是:

将pandas导入为pd导入 matplotlib.pyplot 作为 plt导入 matplotlib.dates 作为 mdatespd_data = pd.DataFrame(data, columns=['id', 'symbol', 'volume', 'high', 'low', 'open', 'datetime','close','datetime_utc','created_at'])pd_data['DOB'] = pd.to_datetime(pd_data['datetime_utc']).dt.strftime('%Y-%m-%d')pd_data.set_index('DOB')打印(pd_data)打印(pd_data.dtypes)ax=pd_data.plot(x='DOB',y='close',kind = 'line')ax.set_ylabel(价格")#ax.pd_data['volume'].plot(secondary_y=True, kind='bar')ax1=pd_data.plot(y='volume',secondary_y=True, ax=ax,kind='bar')ax1.set_ylabel('卷')# 选择你的 xtick 格式字符串date_fmt = '%d-%m-%y'date_formatter = mdates.DateFormatter(date_fmt)ax1.xaxis.set_major_formatter(date_formatter)# 设置每月定位器ax1.xaxis.set_major_locator(mdates.MonthLocator(interval=1))# 设置日期刻度标签的字体和旋转plt.gcf().autofmt_xdate()plt.show()

也在没有ax=ax

的情况下独立试了两个图

ax=pd_data.plot(x='DOB',y='close',kind = 'line')ax.set_ylabel(价格")ax1=pd_data.plot(y='volume',secondary_y=True,kind='bar')ax1.set_ylabel('卷')

然后价格图正确显示年份，而体积图显示 1970 年

如果我交换它们

ax1=pd_data.plot(y='volume',secondary_y=True,kind='bar')ax1.set_ylabel('卷')ax=pd_data.plot(x='DOB',y='close',kind = 'line')ax.set_ylabel(价格")

现在成交量图正确显示年份，而价格图显示年份为 1970 年

我尝试删除secondary_y 并将bar 更改为line.但没有运气

不知何故，第一个图表后的熊猫数据正在改变年份.

解决方案

• 我不建议绘制包含如此多条形的条形图.
• 此答案解释了为什么 xtick 标签存在问题，以及如何解决该问题.
• 使用 pandas.DataFrame.plot 绘图，使用 .set_major_locator
没有问题
• 在 python 3.8.11、pandas 1.3.2、matplotlib 3.4.2

将pandas导入为pd导入 matplotlib.pyplot 作为 plt导入 matplotlib.dates 作为 mdatesimport pandas_datareader as web # conda install -c anaconda pandas-datareader 或 pip install pandas-datareader# 下载数据df = web.DataReader('amzn', data_source='yahoo', start='2015-02-21', end='2021-04-27')# 阴谋ax = df.plot(y='Close', color='magenta', ls='-.', figsize=(10, 6), ylabel='Price ($)')ax1 = df.plot(y='Volume', secondary_y=True, ax=ax, alpha=0.5, rot=0, lw=0.5)ax1.set(ylabel='音量')# 格式date_fmt = '%d-%m-%y'年 = mdates.YearLocator() # 每年yearsFmt = mdates.DateFormatter(date_fmt)ax.xaxis.set_major_locator(年)ax.xaxis.set_major_formatter(yearsFmt)plt.setp(ax.get_xticklabels(), ha=center")plt.show()

---

• 为什么 OP x-tick 标签是从 1970 年开始的?
• 条形图位置被 0 索引(使用熊猫)，0 对应于 1970
  • 请参阅
    • 使用 plt.bar，条形图位置根据日期时间编入索引

    ax = df.plot(y='Close', color='magenta', ls='-.', figsize=(10, 6), ylabel='价格($)', rot=0)plt.setp(ax.get_xticklabels(), ha=center")打印(ax.get_xticks())ax1 = ax.twinx()ax1.bar(df.index, df.Volume)打印(ax1.get_xticks())date_fmt = '%d-%m-%y'年 = mdates.YearLocator() # 每年yearsFmt = mdates.DateFormatter(date_fmt)ax.xaxis.set_major_locator(年)ax.xaxis.set_major_formatter(yearsFmt)[出去]:[16071.16436. 16801. 17167. 17532. 17897. 18262. 18628.][16071.16436. 16801. 17167. 17532. 17897. 18262. 18628.]

    • sns.barplot(x=df.index, y=df.Volume, ax=ax1) 的 xtick 位置为 [ 0 1 2 ... 1553 1554 1555]，所以条形图和线图没有对齐.

    I am trying to draw a stock market graph

    timeseries vs closing price and timeseries vs volume.

    Somehow the x-axis shows the time in 1970

    the following is the graph and the code

    The code is:

    import pandas as pd
    
    import matplotlib.pyplot as plt
    import matplotlib.dates as mdates
    
    
    pd_data = pd.DataFrame(data, columns=['id', 'symbol', 'volume', 'high', 'low', 'open', 'datetime','close','datetime_utc','created_at'])
    
    pd_data['DOB'] = pd.to_datetime(pd_data['datetime_utc']).dt.strftime('%Y-%m-%d')
    
    pd_data.set_index('DOB')
    
    print(pd_data)
    
    print(pd_data.dtypes)
    
    ax=pd_data.plot(x='DOB',y='close',kind = 'line')
    ax.set_ylabel("price")
    
    #ax.pd_data['volume'].plot(secondary_y=True,  kind='bar')
    ax1=pd_data.plot(y='volume',secondary_y=True, ax=ax,kind='bar')
    ax1.set_ylabel('Volumne')
    
    
    # Choose your xtick format string
    date_fmt = '%d-%m-%y'
    
    date_formatter = mdates.DateFormatter(date_fmt)
    ax1.xaxis.set_major_formatter(date_formatter)
    
    # set monthly locator
    ax1.xaxis.set_major_locator(mdates.MonthLocator(interval=1))
    
    # set font and rotation for date tick labels
    plt.gcf().autofmt_xdate()
    
    plt.show()
    

    Also tried the two graphs independently without ax=ax

    ax=pd_data.plot(x='DOB',y='close',kind = 'line')
    ax.set_ylabel("price")
    
    ax1=pd_data.plot(y='volume',secondary_y=True,kind='bar')
    ax1.set_ylabel('Volumne')
    

    then price graph shows years properly whereas volumen graph shows 1970

    And if i swap them

    ax1=pd_data.plot(y='volume',secondary_y=True,kind='bar')
    ax1.set_ylabel('Volumne')
    
    ax=pd_data.plot(x='DOB',y='close',kind = 'line')
    ax.set_ylabel("price")
    

    Now the volume graph shows years properly whereas the price graph shows the years as 1970

    I tried removing secondary_y and also changing bar to line. BUt no luck

    Somehow pandas Data after first graph is changing the year.

    解决方案
    • I do not advise plotting a bar plot with such a numerous amount of bars.
    • This answer explains why there is an issue with the xtick labels, and how to resolve the issue.
    • Plotting with pandas.DataFrame.plot works without issue with .set_major_locator
    • Tested in python 3.8.11, pandas 1.3.2, matplotlib 3.4.2

    import pandas as pd
    import matplotlib.pyplot as plt
    import matplotlib.dates as mdates
    import pandas_datareader as web  # conda install -c anaconda pandas-datareader or pip install pandas-datareader
    
    # download data
    df = web.DataReader('amzn', data_source='yahoo', start='2015-02-21', end='2021-04-27')
    
    # plot
    ax = df.plot(y='Close', color='magenta', ls='-.', figsize=(10, 6), ylabel='Price ($)')
    
    ax1 = df.plot(y='Volume', secondary_y=True, ax=ax, alpha=0.5, rot=0, lw=0.5)
    ax1.set(ylabel='Volume')
    
    # format
    date_fmt = '%d-%m-%y'
    years = mdates.YearLocator()   # every year
    yearsFmt = mdates.DateFormatter(date_fmt)
    
    ax.xaxis.set_major_locator(years)
    ax.xaxis.set_major_formatter(yearsFmt)
    
    plt.setp(ax.get_xticklabels(), ha="center")
    plt.show()
    

    ---

    • Why are the OP x-tick labels starting from 1970?
    • Bar plots locations are being 0 indexed (with pandas), and 0 corresponds to 1970
      • See Pandas bar plot changes date format
      • Most solutions with bar plots simply reformat the label to the appropriate datetime, however this is cosmetic and will not align the locations between the line plot and bar plot
      • Solution 2 of this answer shows how to change the tick locators, but is really not worth the extra code, when plt.bar can be used.

    print(pd.to_datetime(ax1.get_xticks()))
    
    DatetimeIndex([          '1970-01-01 00:00:00',
                   '1970-01-01 00:00:00.000000001',
                   '1970-01-01 00:00:00.000000002',
                   '1970-01-01 00:00:00.000000003',
                   ...
                   '1970-01-01 00:00:00.000001552',
                   '1970-01-01 00:00:00.000001553',
                   '1970-01-01 00:00:00.000001554',
                   '1970-01-01 00:00:00.000001555'],
                  dtype='datetime64[ns]', length=1556, freq=None)
    

    ax = df.plot(y='Close', color='magenta', ls='-.', figsize=(10, 6), ylabel='Price ($)')
    print(ax.get_xticks())
    ax1 = df.plot(y='Volume', secondary_y=True, ax=ax, kind='bar')
    print(ax1.get_xticks())
    ax1.set_xlim(0, 18628.)
    
    date_fmt = '%d-%m-%y'
    years = mdates.YearLocator()   # every year
    yearsFmt = mdates.DateFormatter(date_fmt)
    
    ax.xaxis.set_major_locator(years)
    ax.xaxis.set_major_formatter(yearsFmt)
    
    [out]:
    [16071. 16436. 16801. 17167. 17532. 17897. 18262. 18628.]  ← ax tick locations
    [   0    1    2 ... 1553 1554 1555]  ← ax1 tick locations
    

    • With plt.bar the bar plot locations are indexed based on the datetime

    ax = df.plot(y='Close', color='magenta', ls='-.', figsize=(10, 6), ylabel='Price ($)', rot=0)
    plt.setp(ax.get_xticklabels(), ha="center")
    print(ax.get_xticks())
    
    ax1 = ax.twinx()
    ax1.bar(df.index, df.Volume)
    print(ax1.get_xticks())
    
    date_fmt = '%d-%m-%y'
    years = mdates.YearLocator()   # every year
    yearsFmt = mdates.DateFormatter(date_fmt)
    
    ax.xaxis.set_major_locator(years)
    ax.xaxis.set_major_formatter(yearsFmt)
    
    [out]:
    [16071. 16436. 16801. 17167. 17532. 17897. 18262. 18628.]
    [16071. 16436. 16801. 17167. 17532. 17897. 18262. 18628.]
    

    • sns.barplot(x=df.index, y=df.Volume, ax=ax1) has xtick locations as [ 0 1 2 ... 1553 1554 1555], so the bar plot and line plot did not align.

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