matplotlib烛台图错误xy =（t-OFFSET，更低），TypeError：-：'datetime.date'和'float'的不受支持的操作数类型 [英] matplotlib candlestick chart error xy = (t-OFFSET, lower), TypeError: unsupported operand type(s) for -: 'datetime.date' and 'float'

问题描述

我正在尝试使用matplotplib绘制烛台图。我已经查询了数据库，返回了相关数据，并以所需的格式（日期，打开，关闭，高，低）将其附加到名为CandleAr的问题中。

I am trying to plot a candlestick chart using matplotplib. I have queried my database, returned the relevant data and appended in to an anrray named candleAr, in the required format (date,open,close,high,low)

My代码如下：

import matplotlib.pyplot as plt
import numpy as np
import matplotlib.ticker as mticker
import matplotlib.dates as mdates
from matplotlib.finance import candlestick


candleAr=[]

cursor = conx.cursor()
query= 'SELECT ticker,date,time,open,low,high,close FROM eurusd WHERE date > "2013-02-28"'
cursor.execute(query)
for line in cursor:
    #appendLine in correct format for candlesticks - date,open,close,high,low
    appendLine = line[1],line[3],line[6],line[5],line[4]
    candleAr.append(appendLine)


fig = plt.figure()
ax1 = plt.subplot(1,1,1)
candlestick(ax1, candleAr, width=1, colorup='g', colordown='r')

ax1.grid(True)


plt.xlabel('Date')
plt.ylabel('Price')
plt.show()

但是我收到以下错误消息：

However I am getting the following error message:

Traceback (most recent call last):
  File "C:\Users\Stuart\Desktop\Python Programming\Apache\Liclipse\Andres-Apache\FX\fx2.py", line 53, in <module>
candlestick(ax1, candleAr, width=1, colorup='g', colordown='r')
  File "C:\Users\Stuart\AppData\Local\Enthought\Canopy32\User\lib\site-packages\matplotlib\finance.py", line 359, in candlestick
xy    = (t-OFFSET, lower),
TypeError: unsupported operand type(s) for -: 'datetime.date' and 'float'

当我打印出我的CandleAr，我得到以下信息（我仅包括一个示例的前几个结果）：

When I print out my candleAr, I get the following (I have just included the first couple of results for an example):

[(datetime.date(2013, 3, 1), 1.306, 1.305, 1.306, 1.305), (datetime.date(2013, 3, 1), 1.305, 1.306, 1.306, 1.305)

所以毫无疑问，存在与错误消息相关的日期时间和浮点数，但是从matplotlib导入的烛台肯定可以处理日期时间和浮点数-我的意思是传递给它以建立与价格和日期有关的图表，如果没有日期/日期时间和浮动的话！??

So there are the datetime and floats relating to the error message no doubt, but surely the candlestick import from matplotlib can handle datetimes and floats - I mean what else can be passed to it to build a chart related to prices and dates, if not dates/datetimes and floats!??

任何人都可以指出我在做什么

Would anyone be able to point out what i am doing wrong?

推荐答案

Matplotlib使用浮点数表示序数（从0001-01-01算起的天数），用小数点表示

Matplotlib uses floating point numbers representing ordinals (counting days from 0001-01-01), with decimals representing fractions of a day.

这记录在 烛台文档字符串：

This is documented in the candlestick docstring:

时间必须采用 float 天的格式-请参见 date2num

time must be in float days format - see date2num

matplotlib.dates 模块为您提供了将 datetime 对象转换为此类数字的工具：

The matplotlib.dates module gives you tools to convert datetime objects to such numbers:

>>> from datetime import date
>>> from matplotlib.dates import date2num
>>> date2num(date(2013, 3, 1))
734928.0

对于您的代码看起来像这样：

For your code that looks like:

from matplotlib.dates import date2num

appendLine = date2num(line[1]), line[3], line[6], line[5], line[4]

对于 datetime.date（）基本上可以归结为 datetime.date.toordinal（）作为浮点数而不是整数。

For datetime.date() this basically comes down to datetime.date.toordinal() as a float instead of an integer.

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