I think you either need to escape the \ as \\ or use a raw string .i.e do
r'$\alpha$' otherwise \a gets interpreted as control character.
try entering '\alpha' in a regular python prompt and you will se what
happens.
Best
Jens
tir. 28. jul. 2015 kl. 16.01 skrev Joao Quinta da Fonseca <
joao.fons...@manchester.ac.uk>:
> I am trying to use LaTeX on the ylabel of a plot using:
>
> plt.ylabel("$\alpha$”)
>
> and I am seeing very inconsistent behaviour. If I use $\alpha$ I get an
> error (see below), but \gamma is fine. $\tau does not give an error but
> plots a strange character.
>
> Can you help? thanks
>
> Joao
>
>
> Using $\alpha$ like above gives a long error message:
>
> ---------------------------------------------------------------------------
> ValueError
> Traceback (most recent call last)
>
> /Users/joao/anaconda/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)
>
>
>
> /Users/joao/anaconda/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))
>
>
>
> /Users/joao/anaconda/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':
>
>
>
> /Users/joao/anaconda/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)
>
>
>
> /Users/joao/anaconda/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
>
>
>
> /Users/joao/anaconda/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()
>
>
>
> /Users/joao/anaconda/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
>
>
>
> /Users/joao/anaconda/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')
>
>
>
> /Users/joao/anaconda/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
>
>
>
> /Users/joao/anaconda/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')
>
>
>
> /Users/joao/anaconda/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
>
>
>
> /Users/joao/anaconda/lib/python2.7/site-packages/matplotlib/axis.pyc in
> draw(self, renderer, *args, **kwargs)
> 1126 self._update_label_position(ticklabelBoxes,
> ticklabelBoxes2)
> 1127
> -> 1128 self.label.draw(renderer)
> 1129
> 1130 self._update_offset_text_position(ticklabelBoxes,
> ticklabelBoxes2)
>
>
>
> /Users/joao/anaconda/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
>
>
>
> /Users/joao/anaconda/lib/python2.7/site-packages/matplotlib/text.pyc in
> draw(self, renderer)
> 593 renderer.open_group('text', self.get_gid())
> 594
> --> 595 bbox, info, descent = self._get_layout(renderer)
> 596 trans = self.get_transform()
> 597
>
>
>
> /Users/joao/anaconda/lib/python2.7/site-packages/matplotlib/text.pyc in
> _get_layout(self, renderer)
> 318
> w, h, d =
> renderer.get_text_width_height_descent(clean_line,
>
> 319
> self._fontproperties,
> --> 320
> ismath=ismath)
>
> 321 else:
> 322 w, h, d = 0, 0, 0
>
>
>
> /Users/joao/anaconda/lib/python2.7/site-packages/matplotlib/backends/backend_agg.pyc
> in get_text_width_height_descent(self, s, prop, ismath)
> 226 if ismath:
> 227 ox, oy, width, height, descent, fonts, used_characters
> = \
> --> 228 self.mathtext_parser.parse(s, self.dpi, prop)
> 229 return width, height, descent
> 230
>
>
>
> /Users/joao/anaconda/lib/python2.7/site-packages/matplotlib/mathtext.pyc
> in parse(self, s, dpi, prop)
> 3003 self.__class__._parser = Parser()
> 3004
> -> 3005 box = self._parser.parse(s, font_output, fontsize, dpi)
> 3006 font_output.set_canvas_size(box.width, box.height,
> box.depth)
> 3007 result = font_output.get_results(box)
>
>
>
> /Users/joao/anaconda/lib/python2.7/site-packages/matplotlib/mathtext.pyc
> in parse(self, s, fonts_object, fontsize, dpi)
> 2337 err.line,
> 2338 " " * (err.column - 1) + "^",
> -> 2339
> six.text_type(err)]))
>
> 2340 self._state_stack = None
> 2341 self._em_width_cache = {}
>
>
>
> ValueError
> :
> $ lpha$
> ^
> Expected end of text (at char 0), (line:1, col:1)
>
>
>
>
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