Plot numpy datetime64 with matplotlib

Question

I have two numpy arrays 1D, one is time of measurement in datetime64 format, for example:

array([2011-11-15 01:08:11, 2011-11-16 02:08:04, ..., 2012-07-07 11:08:00], dtype=datetime64[us]) 

and other array of same length and dimension with integer data.
I'd like to make a plot in matplotlib time vs data. If I put the data directly, this is what I get:

plot(timeSeries, data) 

Is there a way to get time in more natural units? For example in this case months/year would be fine.

EDIT:
I have tried Gustav Larsson's suggestion however I get an error:

Out[128]: [<matplotlib.lines.Line2D at 0x419aad0>] --------------------------------------------------------------------------- OverflowError                             Traceback (most recent call last) /usr/lib/python2.7/dist-packages/IPython/zmq/pylab/backend_inline.pyc in show(close)     100     try:     101         for figure_manager in Gcf.get_all_fig_managers(): --> 102             send_figure(figure_manager.canvas.figure)     103     finally:     104         show._to_draw = []  /usr/lib/python2.7/dist-packages/IPython/zmq/pylab/backend_inline.pyc in send_figure(fig)     209     """     210     fmt = InlineBackend.instance().figure_format --> 211     data = print_figure(fig, fmt)     212     # print_figure will return None if there's nothing to draw:     213     if data is None:  /usr/lib/python2.7/dist-packages/IPython/core/pylabtools.pyc in print_figure(fig, fmt)     102     try:     103         bytes_io = BytesIO() --> 104         fig.canvas.print_figure(bytes_io, format=fmt, bbox_inches='tight')     105         data = bytes_io.getvalue()     106     finally:  /usr/lib/pymodules/python2.7/matplotlib/backend_bases.pyc in print_figure(self, filename, dpi, facecolor, edgecolor, orientation, format, **kwargs)    1981                     orientation=orientation,    1982                     dryrun=True, -> 1983                     **kwargs)    1984                 renderer = self.figure._cachedRenderer    1985                 bbox_inches = self.figure.get_tightbbox(renderer)  /usr/lib/pymodules/python2.7/matplotlib/backends/backend_agg.pyc in print_png(self, filename_or_obj, *args, **kwargs)     467      468     def print_png(self, filename_or_obj, *args, **kwargs): --> 469         FigureCanvasAgg.draw(self)     470         renderer = self.get_renderer()     471         original_dpi = renderer.dpi  /usr/lib/pymodules/python2.7/matplotlib/backends/backend_agg.pyc in draw(self)     419      420         try: --> 421             self.figure.draw(self.renderer)     422         finally:     423             RendererAgg.lock.release()  /usr/lib/pymodules/python2.7/matplotlib/artist.pyc in draw_wrapper(artist, renderer, *args, **kwargs)      53     def draw_wrapper(artist, renderer, *args, **kwargs):      54         before(artist, renderer) ---> 55         draw(artist, renderer, *args, **kwargs)      56         after(artist, renderer)      57   /usr/lib/pymodules/python2.7/matplotlib/figure.pyc in draw(self, renderer)     896         dsu.sort(key=itemgetter(0))     897         for zorder, a, func, args in dsu: --> 898             func(*args)     899      900         renderer.close_group('figure')  /usr/lib/pymodules/python2.7/matplotlib/artist.pyc in draw_wrapper(artist, renderer, *args, **kwargs)      53     def draw_wrapper(artist, renderer, *args, **kwargs):      54         before(artist, renderer) ---> 55         draw(artist, renderer, *args, **kwargs)      56         after(artist, renderer)      57   /usr/lib/pymodules/python2.7/matplotlib/axes.pyc in draw(self, renderer, inframe)    1995     1996         for zorder, a in dsu: -> 1997             a.draw(renderer)    1998     1999         renderer.close_group('axes')  /usr/lib/pymodules/python2.7/matplotlib/artist.pyc in draw_wrapper(artist, renderer, *args, **kwargs)      53     def draw_wrapper(artist, renderer, *args, **kwargs):      54         before(artist, renderer) ---> 55         draw(artist, renderer, *args, **kwargs)      56         after(artist, renderer)      57   /usr/lib/pymodules/python2.7/matplotlib/axis.pyc in draw(self, renderer, *args, **kwargs)    1039         renderer.open_group(__name__)    1040  -> 1041         ticks_to_draw = self._update_ticks(renderer)    1042         ticklabelBoxes, ticklabelBoxes2 = self._get_tick_bboxes(ticks_to_draw, renderer)    1043   /usr/lib/pymodules/python2.7/matplotlib/axis.pyc in _update_ticks(self, renderer)     929      930         interval = self.get_view_interval() --> 931         tick_tups = [ t for t in self.iter_ticks()]     932         if self._smart_bounds:     933             # handle inverted limits  /usr/lib/pymodules/python2.7/matplotlib/axis.pyc in iter_ticks(self)     876         Iterate through all of the major and minor ticks.     877         """ --> 878         majorLocs = self.major.locator()     879         majorTicks = self.get_major_ticks(len(majorLocs))     880         self.major.formatter.set_locs(majorLocs)  /usr/lib/pymodules/python2.7/matplotlib/dates.pyc in __call__(self)     747     def __call__(self):     748         'Return the locations of the ticks' --> 749         self.refresh()     750         return self._locator()     751   /usr/lib/pymodules/python2.7/matplotlib/dates.pyc in refresh(self)     756     def refresh(self):     757         'Refresh internal information based on current limits.' --> 758         dmin, dmax = self.viewlim_to_dt()     759         self._locator = self.get_locator(dmin, dmax)     760   /usr/lib/pymodules/python2.7/matplotlib/dates.pyc in viewlim_to_dt(self)     528     def viewlim_to_dt(self):     529         vmin, vmax = self.axis.get_view_interval() --> 530         return num2date(vmin, self.tz), num2date(vmax, self.tz)     531      532     def _get_unit(self):  /usr/lib/pymodules/python2.7/matplotlib/dates.pyc in num2date(x, tz)     287     """     288     if tz is None: tz = _get_rc_timezone() --> 289     if not cbook.iterable(x): return _from_ordinalf(x, tz)     290     else: return [_from_ordinalf(val, tz) for val in x]     291   /usr/lib/pymodules/python2.7/matplotlib/dates.pyc in _from_ordinalf(x, tz)     201     if tz is None: tz = _get_rc_timezone()     202     ix = int(x) --> 203     dt = datetime.datetime.fromordinal(ix)     204     remainder = float(x) - ix     205     hour, remainder = divmod(24*remainder, 1)  OverflowError: signed integer is greater than maximum 

Could this be an bug? Or am I missing something. I also tried something simple:

import matplotlib.pyplot as plt import numpy as np dates=np.array(["2011-11-13", "2011-11-14", "2011-11-15", "2011-11-16", "2011-11-19"], dtype='datetime64[us]') data=np.array([1, 2, 3, 4, 5]) plt.plot_date(dates, data) plt.show() 

I still get this error:

OverflowError: signed integer is greater than maximum 

I don't understand what am I doing wrong. ipython 0.13, matplotlib 1.1, Ubuntu 12.04 x64.

FINAL EDIT:
It seems that matplotlib doesn't support dtype=datetime64, so I needed to convert the timeSeries to ordinary datetime.datetime from datetime.

Answer 1

from datetime import datetime a=np.datetime64('2002-06-28').astype(datetime) plot_date(a,2) 

Answer 2

You might want to try this:

plot_date(timeSeries, data) 

By default, the x axis will be considered a date axis, and y a regular one. This can be customized.