我有一个带有dtf列的DataFrame Data ...
print(dft.Date)
print(type(dft))
print(type(dft.iloc[0]["Date"]))
1340 2018-01-04 00:06:58
1341 2018-01-04 00:17:18
1342 2018-01-04 00:27:38
1343 2018-01-04 00:37:59
1344 2018-01-04 00:48:19
1345 2018-01-04 00:58:41
1346 2018-01-04 01:09:01
1347 2018-01-04 01:19:21
1348 2018-01-04 01:29:41
1349 2018-01-04 01:40:02
Name: Date, dtype: object
<class 'pandas.core.frame.DataFrame'>
<class 'pandas._libs.tslib.Timestamp'>
...以及一列值X有时带有许多np.NaN值。即使列np.NaN中只有X，我也想保持灵活性并绘制图形（不包含任何内容）。当存在至少个不等于np.NaN的值时，一切工作正常：
dft["X"] = np.array([1] + [np.NaN for i in range(9)])
plt.plot(dft.Date, dft.X) # works as expected
但是只要出现仅 np.NaN，我就会尝试绘制：
dft["X"] = np.array([np.NaN for i in range(10)])
plt.plot(dft.Date, dft.X)
..我收到以下错误消息：
[<matplotlib.lines.Line2D at 0x1ba20c7f128>]
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
C:\ProgramData\Anaconda3\lib\site-packages\IPython\core\formatters.py in __call__(self, obj)
339 pass
340 else:
--> 341 return printer(obj)
342 # Finally look for special method names
343 method = get_real_method(obj, self.print_method)
C:\ProgramData\Anaconda3\lib\site-packages\IPython\core\pylabtools.py in <lambda>(fig)
236
237 if 'png' in formats:
--> 238 png_formatter.for_type(Figure, lambda fig: print_figure(fig, 'png', **kwargs))
239 if 'retina' in formats or 'png2x' in formats:
240 png_formatter.for_type(Figure, lambda fig: retina_figure(fig, **kwargs))
C:\ProgramData\Anaconda3\lib\site-packages\IPython\core\pylabtools.py in print_figure(fig, fmt, bbox_inches, **kwargs)
120
121 bytes_io = BytesIO()
--> 122 fig.canvas.print_figure(bytes_io, **kw)
123 data = bytes_io.getvalue()
124 if fmt == 'svg':
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\backend_bases.py in print_figure(self, filename, dpi, facecolor, edgecolor, orientation, format, **kwargs)
2214 orientation=orientation,
2215 dryrun=True,
-> 2216 **kwargs)
2217 renderer = self.figure._cachedRenderer
2218 bbox_inches = self.figure.get_tightbbox(renderer)
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\backends\backend_agg.py in print_png(self, filename_or_obj, *args, **kwargs)
505
506 def print_png(self, filename_or_obj, *args, **kwargs):
--> 507 FigureCanvasAgg.draw(self)
508 renderer = self.get_renderer()
509 original_dpi = renderer.dpi
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\backends\backend_agg.py in draw(self)
428 # if toolbar:
429 # toolbar.set_cursor(cursors.WAIT)
--> 430 self.figure.draw(self.renderer)
431 finally:
432 # if toolbar:
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\artist.py in draw_wrapper(artist, renderer, *args, **kwargs)
53 renderer.start_filter()
54
---> 55 return draw(artist, renderer, *args, **kwargs)
56 finally:
57 if artist.get_agg_filter() is not None:
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\figure.py in draw(self, renderer)
1297
1298 mimage._draw_list_compositing_images(
-> 1299 renderer, self, artists, self.suppressComposite)
1300
1301 renderer.close_group('figure')
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\image.py in _draw_list_compositing_images(renderer, parent, artists, suppress_composite)
136 if not_composite or not has_images:
137 for a in artists:
--> 138 a.draw(renderer)
139 else:
140 # Composite any adjacent images together
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\artist.py in draw_wrapper(artist, renderer, *args, **kwargs)
53 renderer.start_filter()
54
---> 55 return draw(artist, renderer, *args, **kwargs)
56 finally:
57 if artist.get_agg_filter() is not None:
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\axes\_base.py in draw(self, renderer, inframe)
2435 renderer.stop_rasterizing()
2436
-> 2437 mimage._draw_list_compositing_images(renderer, self, artists)
2438
2439 renderer.close_group('axes')
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\image.py in _draw_list_compositing_images(renderer, parent, artists, suppress_composite)
136 if not_composite or not has_images:
137 for a in artists:
--> 138 a.draw(renderer)
139 else:
140 # Composite any adjacent images together
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\artist.py in draw_wrapper(artist, renderer, *args, **kwargs)
53 renderer.start_filter()
54
---> 55 return draw(artist, renderer, *args, **kwargs)
56 finally:
57 if artist.get_agg_filter() is not None:
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\axis.py in draw(self, renderer, *args, **kwargs)
1131 renderer.open_group(__name__)
1132
-> 1133 ticks_to_draw = self._update_ticks(renderer)
1134 ticklabelBoxes, ticklabelBoxes2 = self._get_tick_bboxes(ticks_to_draw,
1135 renderer)
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\axis.py in _update_ticks(self, renderer)
972
973 interval = self.get_view_interval()
--> 974 tick_tups = list(self.iter_ticks())
975 if self._smart_bounds and tick_tups:
976 # handle inverted limits
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\axis.py in iter_ticks(self)
915 Iterate through all of the major and minor ticks.
916 """
--> 917 majorLocs = self.major.locator()
918 majorTicks = self.get_major_ticks(len(majorLocs))
919 self.major.formatter.set_locs(majorLocs)
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\dates.py in __call__(self)
1095 def __call__(self):
1096 'Return the locations of the ticks'
-> 1097 self.refresh()
1098 return self._locator()
1099
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\dates.py in refresh(self)
1115 def refresh(self):
1116 'Refresh internal information based on current limits.'
-> 1117 dmin, dmax = self.viewlim_to_dt()
1118 self._locator = self.get_locator(dmin, dmax)
1119
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\dates.py in viewlim_to_dt(self)
873 vmin, vmax = vmax, vmin
874
--> 875 return num2date(vmin, self.tz), num2date(vmax, self.tz)
876
877 def _get_unit(self):
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\dates.py in num2date(x, tz)
464 tz = _get_rc_timezone()
465 if not cbook.iterable(x):
--> 466 return _from_ordinalf(x, tz)
467 else:
468 x = np.asarray(x)
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\dates.py in _from_ordinalf(x, tz)
277
278 ix = int(x)
--> 279 dt = datetime.datetime.fromordinal(ix).replace(tzinfo=UTC)
280
281 remainder = float(x) - ix
ValueError: ordinal must be >= 1
<matplotlib.figure.Figure at 0x1ba20c5c630>
我已经尝试根据this post转换Date列，并使用Date和许多其他变通方法来转换dft.Date.astype('O')。什么都没用。
我不想丢弃或填充NaN。