pandas 绘制数据帧会引发序数值的误差必须 >= 1
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Plotting dataframe raises error of ordinal value must be >= 1
提问by David Michael Gang
I follow the tutorial at http://nbviewer.ipython.org/github/jvns/pandas-cookbook/blob/v0.1/cookbook/Chapter%205%20-%20Combining%20dataframes%20and%20scraping%20Canadian%20weather%20data.ipynb
我按照http://nbviewer.ipython.org/github/jvns/pandas-cookbook/blob/v0.1/cookbook/Chapter%205%20-%20Combining%20dataframes%20and%20scraping%20Canadian%20weather% 上的教程进行操作20data.ipynb
I have a pandas dataframe
我有一个Pandas数据框
weather_mar2012['Temp (?°C)']
weather_mar2012['Temp (?°C)']
Out[30]:
Date/Time
2012-03-01 00:00:00 -5.5
2012-03-01 01:00:00 -5.7
2012-03-01 02:00:00 -5.4
When trying to plot it i get an error
尝试绘制时出现错误
weather_mar2012['Temp (?°C)'].plot(figsize=(15, 5))
---------------------------------------------------------------------------
ValueError Traceback (most recent call last) <ipython-input-31-21c79ba7d5ef> in <module>()
----> 1 weather_mar2012['Temp (?°C)'].plot(figsize=(15, 5))
/home/vagrant/anaconda3/lib/python3.4/site-packages/pandas/tools/plotting.py in plot_series(data, kind, ax, figsize, use_index, title, grid, legend, style, logx, logy, loglog, xticks, yticks, xlim, ylim, rot, fontsize, colormap, table, yerr, xerr, label, secondary_y, **kwds) 2486 yerr=yerr, xerr=xerr, 2487 label=label, secondary_y=secondary_y,
-> 2488 **kwds) 2489 2490
/home/vagrant/anaconda3/lib/python3.4/site-packages/pandas/tools/plotting.py in _plot(data, x, y, subplots, ax, kind, **kwds) 2292 plot_obj = klass(data, subplots=subplots, ax=ax, kind=kind, **kwds) 2293
-> 2294 plot_obj.generate() 2295 plot_obj.draw() 2296 return plot_obj.result
/home/vagrant/anaconda3/lib/python3.4/site-packages/pandas/tools/plotting.py in generate(self)
922 self._make_legend()
923 self._post_plot_logic()
--> 924 self._adorn_subplots()
925
926 def _args_adjust(self):
/home/vagrant/anaconda3/lib/python3.4/site-packages/pandas/tools/plotting.py in _adorn_subplots(self) 1052 ax.set_xticklabels(xticklabels) 1053 self._apply_axis_properties(ax.xaxis, rot=self.rot,
-> 1054 fontsize=self.fontsize) 1055 elif self.orientation == 'horizontal': 1056 if self._need_to_set_index:
/home/vagrant/anaconda3/lib/python3.4/site-packages/pandas/tools/plotting.py in _apply_axis_properties(self, axis, rot, fontsize) 1061 1062 def _apply_axis_properties(self, axis, rot=None, fontsize=None):
-> 1063 labels = axis.get_majorticklabels() + axis.get_minorticklabels() 1064 for label in labels: 1065 if rot is not None:
/home/vagrant/anaconda3/lib/python3.4/site-packages/matplotlib/axis.py in get_majorticklabels(self) 1155 def get_majorticklabels(self): 1156 'Return a list of Text instances for the major ticklabels'
-> 1157 ticks = self.get_major_ticks() 1158 labels1 = [tick.label1 for tick in ticks if tick.label1On] 1159 labels2 = [tick.label2 for tick in ticks if tick.label2On]
/home/vagrant/anaconda3/lib/python3.4/site-packages/matplotlib/axis.py in get_major_ticks(self, numticks) 1284 'get the tick instances; grow as necessary' 1285 if numticks is None:
-> 1286 numticks = len(self.get_major_locator()()) 1287 if len(self.majorTicks) < numticks: 1288 # update the new tick label properties from the old
/home/vagrant/anaconda3/lib/python3.4/site-packages/matplotlib/dates.py in __call__(self)
863 def __call__(self):
864 'Return the locations of the ticks'
--> 865 self.refresh()
866 return self._locator()
867
/home/vagrant/anaconda3/lib/python3.4/site-packages/matplotlib/dates.py in refresh(self)
880 def refresh(self):
881 'Refresh internal information based on current limits.'
--> 882 dmin, dmax = self.viewlim_to_dt()
883 self._locator = self.get_locator(dmin, dmax)
884
/home/vagrant/anaconda3/lib/python3.4/site-packages/matplotlib/dates.py in viewlim_to_dt(self)
624 def viewlim_to_dt(self):
625 vmin, vmax = self.axis.get_view_interval()
--> 626 return num2date(vmin, self.tz), num2date(vmax, self.tz)
627
628 def _get_unit(self):
/home/vagrant/anaconda3/lib/python3.4/site-packages/matplotlib/dates.py in num2date(x, tz)
343 tz = _get_rc_timezone()
344 if not cbook.iterable(x):
--> 345 return _from_ordinalf(x, tz)
346 else:
347 x = np.asarray(x)
/home/vagrant/anaconda3/lib/python3.4/site-packages/matplotlib/dates.py in _from_ordinalf(x, tz)
223 tz = _get_rc_timezone()
224 ix = int(x)
--> 225 dt = datetime.datetime.fromordinal(ix)
226 remainder = float(x) - ix
227 hour, remainder = divmod(24 * remainder, 1)
ValueError: ordinal must be >= 1
What does it mean?
这是什么意思？
How can i fix this?
我怎样才能解决这个问题？
回答by Mat
I was getting this error in ipython even with current pandas 0.20.3
即使使用当前的 Pandas 0.20.3，我也在 ipython 中收到此错误
Traced it down to having run a script beforehand which saved a figure with a different index, but hadn't done plt.show()as the figure had been saved and I didn't need to see it.
追溯到之前运行了一个脚本，该脚本保存了一个具有不同索引的图形，但没有这样做，plt.show()因为图形已被保存，我不需要看到它。
So as @naught101 hinted, forcing plt.close('all')before showing the next figure fixes the issue. Probably good practice at the end of scripts anyway.
正如@naught101 暗示的那样，plt.close('all')在显示下一个图之前强制解决了这个问题。无论如何，在脚本结束时可能是很好的做法。
回答by citynorman
This was a bug in pandas: 0.18.1 and fixed in 0.19.2, eg run conda upgrade pandas
这是 Pandas 中的一个错误：0.18.1 并在 0.19.2 中修复，例如运行 conda upgrade pandas
