Question

我有一个这样的数据框df：

        datetime          duration
0   2018-10-08 13:30:00    03:00
1   2018-10-08 16:40:00    00:11
2   2018-10-08 21:30:00    03:19
3   2018-10-09 03:21:00    04:27
4   2018-10-09 07:49:00    02:11

两列的两种类型均为pandas.core.series.Series：

In[20]:  type(df_sleep['datetime'])
Out[20]: pandas.core.series.Series

In[21]:  type(df_sleep['duration'])
Out[20]: pandas.core.series.Series

我想使用以下内容转换数据：

import matplotlib.dates as dates
dates.date2num(df_sleep['datetime'])
dates.date2num(df_sleep['duration'])

“日期时间”列有效时，“持续时间”列显示以下错误：

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-22-3720cbfdbdfa> in <module>()
----> 1 dates.date2num(df_sleep['duration'])

/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/matplotlib/dates.py in date2num(d)
    450         if not d.size:
    451             return d
--> 452         return _to_ordinalf_np_vectorized(d)
    453 
    454 

/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/numpy/lib/function_base.py in __call__(self, *args, **kwargs)
   2753             vargs.extend([kwargs[_n] for _n in names])
   2754 
-> 2755         return self._vectorize_call(func=func, args=vargs)
   2756 
   2757     def _get_ufunc_and_otypes(self, func, args):

/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/numpy/lib/function_base.py in _vectorize_call(self, func, args)
   2823             res = func()
   2824         else:
-> 2825             ufunc, otypes = self._get_ufunc_and_otypes(func=func, args=args)
   2826 
   2827             # Convert args to object arrays first

/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/numpy/lib/function_base.py in _get_ufunc_and_otypes(self, func, args)
   2783 
   2784             inputs = [arg.flat[0] for arg in args]
-> 2785             outputs = func(*inputs)
   2786 
   2787             # Performance note: profiling indicates that -- for simple

/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/matplotlib/dates.py in _to_ordinalf(dt)
    253         tzi = UTC
    254 
--> 255     base = float(dt.toordinal())
    256 
    257     # If it's sufficiently datetime-like, it will have a `date()` method

AttributeError: 'str' object has no attribute 'toordinal'

有人知道吗？我的最终目标是使用Matplotlib在“ datetime”（x轴）-“ duration”（y轴）中绘制数据。我想这是因为df ['duration']列仅包含时间，而没有日期，并且无法做转换？我应该怎么做？

非常感谢您的任何建议！

Answer 1

猜猜您的持续时间格式为％H：％M。首先，将列格式更改为datetime。

import pandas as pd
import matplotlib.pyplot as plt
from matplotlib.dates import DateFormatter, date2num

df['datetime'] = pd.to_datetime(df.datetime)
df["duration"] = pd.to_datetime(df["duration"],format="%H:%M")

fig, ax = plt.subplots()

myFmt = DateFormatter("%H:%M:%S")
ax.yaxis.set_major_formatter(myFmt)

ax.plot(df['datetime'], df['duration'])

plt.gcf().autofmt_xdate()

plt.show()

使用date2num（）将时间（无日期）转换为Matplotlib num

1 个答案: