使用Matplotlib在Python中跳过某些值

编程问答 2022-08-16

问题描述

我目前正在使用Alpha Vantage API处理日内股票图表。数据框包含从4:00到20:00的值。但是，在我的matplotlib.pyplot图表中，x轴还包含了晚上20:00到4:00之间的值。我不希望这样做，因为这会混淆美学和“体积”子图。

问：有什么方法可以跳过实际数据框中不存在的x轴值（从20:00到04:00的值）？

As you can see,the Data Frame clearly jumps from 20:00 to 04:00

However in the Matplotlib chart,the x-Axis contains the values from 20:00 to 4:00,messing with the chart

到目前为止的代码。我相信到目前为止一切都正确： 
import pandas as pd
import matplotlib.pyplot as plt
from alpha_vantage.timeseries import TimeSeries
import time
import datetime as dt
from datetime import timedelta as td 
from dateutil.relativedelta import relativedelta

#Accessing and Preparing API
ts = TimeSeries(key=api_key,output_format='pandas')

ticker_input = "TSLA"
interval_input = "15min"
df,Meta_data = ts.get_inTraday(symbol = ticker_input,interval = interval_input,outputsize = 'full')
slice_date = 16*4*5
df = df[0:slice_date]
df = df.iloc[::-1]
df["100ma"] = df["4. close"].rolling(window = 50,min_periods = 0).mean()
df["Close"] = df["4. close"]
df["Date"] = df.index

#Plotting all as 2 different subplots
ax1 = plt.subplot2grid((7,1),(0,0),rowspan = 5,colspan = 1)
ax1.plot(df["Date"],df['Close'])
ax1.plot(df["Date"],df["100ma"],linewidth = 0.5)
plt.xticks(rotation=45)
ax2 = plt.subplot2grid((6,(5,rowspan = 2,colspan = 2,sharex = ax1)
ax2.bar(df["Date"],df["5. volume"])
ax2.axes.xaxis.set_visible(False)
plt.tight_layout()
plt.show()

如果有人可以帮助，那就太好了。我仍然是一个完整的初学者，仅在2周前才开始使用Python。

解决方法

尽管数据获取方法不同，但我们从同一位置获得了数据。以15个单位将其提取后，我通过排除晚上8点之后和下午4点之前的数据来创建图表。我创建代码的前提是您的跳过会打开暂停。一旦设置了NaN，就会跳过您要跳过的内容。

import datetime
import pandas as pd
import numpy as np
import pandas_datareader.data as web
import mplfinance as mpf
# import matplotlib.pyplot as plt

with open('./alpha_vantage_api_key.txt') as f:
    api_key = f.read()

now_ = datetime.datetime.today()

start = datetime.datetime(2019,1,1)
end = datetime.datetime(now_.year,now_.month,now_.day - 1)

symbol = 'TSLA'
df = web.DataReader(symbol,'av-intraday',start,end,api_key=api_key)

df.columns = ['Open','High','Low','Close','Volume']
df.index = pd.to_datetime(df.index)
df["100ma"] = df["Close"].rolling(window = 50,min_periods = 0).mean()
df["Date"] = df.index
df_15 = df.asfreq('15min')
df_15 = df_15[(df_15.index.hour >= 4)&(df_15.index.hour <= 20) ]

import matplotlib.pyplot as plt
fig = plt.figure(figsize=(8,4.5),dpi=144)

#Plotting all as 2 different subplots
ax1 = plt.subplot2grid((7,1),(0,0),rowspan = 5,colspan = 1)
ax1.plot(df_15["Date"],df_15['Close'])
ax1.plot(df_15["Date"],df_15["100ma"],linewidth = 0.5)
plt.xticks(rotation=20)

ax2 = plt.subplot2grid((6,(5,rowspan = 2,colspan = 2,sharex = ax1)
ax2.bar(df_15["Date"],df_15["Volume"])
ax2.axes.xaxis.set_visible(False)
# plt.tight_layout()
plt.show()

enter image description here

,

我使用matplotlib.ticker.formatter修复了它。

我首先创建了一个类，并使用：

class MyFormatter(Formatter):
    def __init__(self,dates,fmt='%Y-%m-%d %H:%M'):
        self.dates = dates
        self.fmt = fmt

    def __call__(self,x,pos=0):
        'Return the label for time x at position pos'
        ind = int(np.round(x))
    if ind >= len(self.dates) or ind < 0:
        return ''
    return self.dates[ind].strftime(self.fmt)

formatter = MyFormatter(df.index)
ax1 = plt.subplot2grid((7,colspan = 1)
ax1.xaxis.set_major_formatter(formatter)
ax1.plot(np.arange(len(df)),df["Close"])
ax1.plot(np.arange(len(df)),df["100ma"],linewidth = 0.5)
ax1.xticks(rotation=45)
ax1.axis([xmin,xmax,ymin,ymax])
ax2 = plt.subplot2grid((6,sharex = ax1)
ax2.bar(np.arange(len(df)),df["5. volume"])

plt.show()

这给了我比以前更平滑的图形，同时也给了r-beginner建议的图形。 https://angular.io/guide/service-worker-config#navigationurls

我唯一的问题是，如果我放大x轴并没有真正改变。它始终具有年，月，日，时和分。显然，当我进一步放大时，我只需要小时和分钟。我还没有弄清楚该怎么做

axis-labelsmatplotlibpython