---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-23-ba47ee7767bc> in <module>()
1 plt.plot(alphas, val, 'k-', linewidth=.75 ,alpha=1.)
2 plt.plot(alphas, -val, 'r-', linewidth=.75 ,alpha=1.)
----> 3 plt.loglog()
4 plt.xlabel(r"$\alpha$")
5 plt.ylabel("covariance")
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/pyplot.pyc in loglog(*args, **kwargs)
2977 ax.hold(hold)
2978 try:
-> 2979 ret = ax.loglog(*args, **kwargs)
2980 draw_if_interactive()
2981 finally:
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/axes/_axes.pyc in loglog(self, *args, **kwargs)
1502 }
1503
-> 1504 self.set_xscale('log', **dx)
1505 self.set_yscale('log', **dy)
1506
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/axes/_base.pyc in set_xscale(self, value, **kwargs)
2605 kwargs['nonposx'] = 'clip'
2606 self.xaxis._set_scale(value, **kwargs)
-> 2607 self.autoscale_view(scaley=False)
2608 self._update_transScale()
2609
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/axes/_base.pyc in autoscale_view(self, tight, scalex, scaley)
1958 x1 += delta
1959 if not _tight:
-> 1960 x0, x1 = xlocator.view_limits(x0, x1)
1961 self.set_xbound(x0, x1)
1962
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/ticker.pyc in view_limits(self, vmin, vmax)
1523 if minpos <= 0 or not np.isfinite(minpos):
1524 raise ValueError(
-> 1525 "Data has no positive values, and therefore can not be "
1526 "log-scaled.")
1527
ValueError: Data has no positive values, and therefore can not be log-scaled.
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/formatters.pyc in __call__(self, obj)
328 pass
329 else:
--> 330 return printer(obj)
331 # Finally look for special method names
332 method = _safe_get_formatter_method(obj, self.print_method)
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/pylabtools.pyc in <lambda>(fig)
205
206 if 'png' in formats:
--> 207 png_formatter.for_type(Figure, lambda fig: print_figure(fig, 'png', **kwargs))
208 if 'retina' in formats or 'png2x' in formats:
209 png_formatter.for_type(Figure, lambda fig: retina_figure(fig, **kwargs))
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/pylabtools.pyc in print_figure(fig, fmt, bbox_inches, **kwargs)
115
116 bytes_io = BytesIO()
--> 117 fig.canvas.print_figure(bytes_io, **kw)
118 data = bytes_io.getvalue()
119 if fmt == 'svg':
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backend_bases.pyc in print_figure(self, filename, dpi, facecolor, edgecolor, orientation, format, **kwargs)
2156 orientation=orientation,
2157 dryrun=True,
-> 2158 **kwargs)
2159 renderer = self.figure._cachedRenderer
2160 bbox_inches = self.figure.get_tightbbox(renderer)
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/backend_agg.pyc in print_png(self, filename_or_obj, *args, **kwargs)
519
520 def print_png(self, filename_or_obj, *args, **kwargs):
--> 521 FigureCanvasAgg.draw(self)
522 renderer = self.get_renderer()
523 original_dpi = renderer.dpi
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/backend_agg.pyc in draw(self)
467
468 try:
--> 469 self.figure.draw(self.renderer)
470 finally:
471 RendererAgg.lock.release()
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/artist.pyc in draw_wrapper(artist, renderer, *args, **kwargs)
57 def draw_wrapper(artist, renderer, *args, **kwargs):
58 before(artist, renderer)
---> 59 draw(artist, renderer, *args, **kwargs)
60 after(artist, renderer)
61
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/figure.pyc in draw(self, renderer)
1083 dsu.sort(key=itemgetter(0))
1084 for zorder, a, func, args in dsu:
-> 1085 func(*args)
1086
1087 renderer.close_group('figure')
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/artist.pyc in draw_wrapper(artist, renderer, *args, **kwargs)
57 def draw_wrapper(artist, renderer, *args, **kwargs):
58 before(artist, renderer)
---> 59 draw(artist, renderer, *args, **kwargs)
60 after(artist, renderer)
61
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/axes/_base.pyc in draw(self, renderer, inframe)
2108
2109 for zorder, a in dsu:
-> 2110 a.draw(renderer)
2111
2112 renderer.close_group('axes')
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/artist.pyc in draw_wrapper(artist, renderer, *args, **kwargs)
57 def draw_wrapper(artist, renderer, *args, **kwargs):
58 before(artist, renderer)
---> 59 draw(artist, renderer, *args, **kwargs)
60 after(artist, renderer)
61
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/axis.pyc in draw(self, renderer, *args, **kwargs)
1112 renderer.open_group(__name__)
1113
-> 1114 ticks_to_draw = self._update_ticks(renderer)
1115 ticklabelBoxes, ticklabelBoxes2 = self._get_tick_bboxes(ticks_to_draw,
1116 renderer)
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/axis.pyc in _update_ticks(self, renderer)
955
956 interval = self.get_view_interval()
--> 957 tick_tups = [t for t in self.iter_ticks()]
958 if self._smart_bounds:
959 # handle inverted limits
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/axis.pyc in iter_ticks(self)
899 Iterate through all of the major and minor ticks.
900 """
--> 901 majorLocs = self.major.locator()
902 majorTicks = self.get_major_ticks(len(majorLocs))
903 self.major.formatter.set_locs(majorLocs)
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/ticker.pyc in __call__(self)
1448 'Return the locations of the ticks'
1449 vmin, vmax = self.axis.get_view_interval()
-> 1450 return self.tick_values(vmin, vmax)
1451
1452 def tick_values(self, vmin, vmax):
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/ticker.pyc in tick_values(self, vmin, vmax)
1466 if vmin <= 0.0 or not np.isfinite(vmin):
1467 raise ValueError(
-> 1468 "Data has no positive values, and therefore can not be "
1469 "log-scaled.")
1470
ValueError: Data has no positive values, and therefore can not be log-scaled.
<matplotlib.figure.Figure at 0x1150272d0>