蜡烛线是股票分析中常用的一种技术指标，通过蜡烛线图可以直观地看出股票价格的变化情况。在Python中，我们可以使用matplotlib库来实现画蜡烛线。

import matplotlib.pyplot as plt
from matplotlib.dates import DateFormatter, WeekdayLocator, DayLocator, MONDAY
from mpl_finance import candlestick_ohlc
import pandas as pd
# 读入数据，这里我们使用Google的股票数据
goog = pd.read_csv('https://www.alphavantage.co/query?function=TIME_SERIES_DAILY&symbol=GOOG&apikey=demo&datatype=csv')
# 处理日期数据，转化为数字
goog['date'] = pd.to_datetime(goog['timestamp'])
goog['date'] = goog['date'].apply(lambda x: DateFormatter('%Y-%m-%d')(x))
goog['date'] = pd.to_datetime(goog['date'])
goog['date'] = goog['date'].apply(lambda x: x.toordinal())
# 绘制蜡烛图
mondays = WeekdayLocator(MONDAY)
alldays = DayLocator()
weekFormatter = DateFormatter('%b %d')
dayFormatter = DateFormatter('%d')
fig, ax = plt.subplots()
fig.subplots_adjust(bottom=0.2)
ax.xaxis.set_major_locator(mondays)
ax.xaxis.set_minor_locator(alldays)
ax.xaxis.set_major_formatter(weekFormatter)
candlestick_ohlc(ax, zip(goog['date'], goog['open'], goog['high'], goog['low'], goog['close']), width=0.6)
ax.xaxis_date()
ax.autoscale_view()
plt.setp(plt.gca().get_xticklabels(), rotation=45, ha='right')
plt.show()

代码中使用了pandas库来读取和处理数据，然后使用matplotlib的candlestick_ohlc()函数绘制蜡烛图。其中，我们将日期转化为数字，并使用WeekdayLocator和DayLocator设置X轴的坐标。最后使用plt.show()函数显示图形。