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) > > > > > ------------------------------------------------------------------------------ > _______________________________________________ > Matplotlib-users mailing list > 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