"ValueError: Invalid RGBA argument: None" when plotting via matplotlib ax.bar() for creating a windrose using custom colormaps

"ValueError: Invalid RGBA argument: None" when plotting via matplotlib ax.bar() for creating a windrose using custom colormaps

我们的目标是创建一个如下图所示的风向玫瑰:

错误本身发生在通过 fig.savefig() 保存绘图时,但到目前为止我意识到错误在于所使用的颜色映射(例如考虑到 )。

尝试将条形图添加到 WindroseAxes() - 轴 - 实例,该实例以前工作得很好。 这可以通过 from windrose import WindroseAxes 实现。 我在这里提到它是否在问题中起作用。

# * Instantiate windrose-axis related to the global figure and the just created rectangle
# NOTE on passing theta-labels: need to be passed, otherwise an error will be thrown like 'keyword "theta_labels" does not exist'
# --> from windrose.py: self.theta_labels = kwargs.pop("theta_labels") or ["E", "N-E", "N", "N-W", "W", "S-W", "S", "S-E"]
ax = WindroseAxes(fig, rect, theta_labels=theta_labels)
fig.add_axes(ax)

使用的数据框的细节

sub_df.info()
None
<class 'pandas.core.frame.DataFrame'>
DatetimeIndex: 7130 entries, 2018-07-01 00:05:00+02:00 to 2018-07-31 23:55:00+02:00
Data columns (total 8 columns):
 #   Column                          Non-Null Count  Dtype  
---  ------                          --------------  -----  
 0   Atm. pressure mean              7130 non-null   float64
 1   Daily cumulative precipitation  7130 non-null   float64
 2   Precipitation                   7130 non-null   float64
 3   RH_mean                         7130 non-null   float64
 4   T_mean                          7130 non-null   float64
 5   Wind direction mean             7130 non-null   float64
 6   Wind speed max                  7130 non-null   float64
 7   Wind speed mean                 7130 non-null   float64
dtypes: float64(8)
memory usage: 821.3 KB

在接下来的内容中,我将描述 ax.bar() - 函数(意图绘制风玫瑰) 和相关的颜色条 是如何绘制的:

# * Define colormap
# Colormap increases the contrast from 0 to 1 in blue (or the color of choice)
# NOTE on type: <matplotlib.colors.LinearSegmentedColormap object at 0x7fd8b7d3d850>
cmap = plt.cm.Blues  # pylint: disable=no-member


## * Get bins for colormap used for all subplots equally * ##
# i) Get maximum value
# Use .max() instead of max(), otherwise NaN could be considered the maximum
real_max_val = df[var_name].max()
# Maximum value here: 11 (m/s)
max_val = real_max_val.round()
# NOTE on scope: when rounded down, add 1 to make it greater than the actual maximum value
if max_val < real_max_val:
    max_val += 1

# ii) Set the bins linearly (not logarithmically as often seen)
# NOTE: units are assumed in meters per second (m/s)
# NOTE on bins: divides each wind-bar into e.g. 6 bins == stepnumber in linspace (default)
# NOTE on minimum value: the lowest possible is 0 m/s
bins_bar_plot = np.linspace(0, max_val, num_of_bins)  # (start, end, stepnumber)
cmap_norm = mpl.colors.Normalize(vmin=0, vmax=max_val)


# * Create plot based on the current sub-df
ax.bar(sub_df['Wind direction mean'],
        sub_df['Wind speed mean'],
        normed=True,
        facecolor=(0.03137254901960784, 0.18823529411764706, 0.4196078431372549, 1.0),
        bins=array([ 0. ,  2.2,  4.4,  6.6,  8.8, 11. ]),
        cmap=cmap,
        alpha=1.0,
        opening=1.0,
        "grey"="grey",
        linewidth=0.1)

涉及到的colorbar是这样实现的:

fig.subplots_adjust(right=0.8)
# [x_coord start, y_coord start, total width, total height] - all in percent of the figure dimensions
cbar_ax = fig.add_axes([0.95, 0.15, 0.025, 0.7])
cbar = mpl.colorbar.ColorbarBase(cbar_ax,
                                    cmap=cmap,
                                    norm=cmap_norm,
                                    spacing='proportional',
                                    alpha=1.0)
cbar.set_label("{} {}".format('Wind speed mean', tools.units("Wind speed")),
                color=None,
                weight=None,
                fontsize=None)
# NOTE: vertically oriented colorbar: y-label
# Length of ticklabels here: 6
new_yticklabels = np.linspace(0, max_val,
                                len(list(cbar.ax.get_yticklabels())))
new_yticklabels = np.around(new_yticklabels, decimals=1)

# New ticklabels here: array([ 0. ,  2.2,  4.4,  6.6,  8.8, 11. ])
cbar.ax.set_yticklabels(new_yticklabels,
                        color=None,
                        weight=None,
                        fontsize=None)

控制台打印的整个错误回溯是:

   ValueError                                Traceback (most recent call last)
    ~/Desktop/Programming/Python/Scripts/General/Plotting/windrose_plotting.py in <module>
        184             textcolor="blue")
        185         # * Carry out plot of the current sub-df
    --> 186         plot.windrose_subplot(
        187             df=df_plot.loc[m_loc],
        188             desired_years=desired_years,

~/Dokumente/Allgemeines_material/Sonstiges/Programming/Python/Scripts/General/Plotting/plotting.py in windrose_subplot(df, figsize, groupby_freq, desired_years, desired_months, theta_labels, max_cols_per_row, ax_title_pos, cmap, y_coord_suptitle_dict, title_font_size, savepath, plot_file_extensions, normed, opening_bar_plot, num_of_bins, edgecolor, edge_linewidth, meteo_loc, add_info, transparent, alpha, label_color, font_weight, special_textfont_size, save_plotting_data_to_plain_text_AS_WELL, save_plotting_data_to_plain_text_ONLY)
   6957 
   6958     # * Finally, either show or save the current plot
-> 6959     aux_plot.show_or_save_plot(path=savepath,
   6960                                basename=titlestr,
   6961                                transparent=transparent,

~/Dokumente/Allgemeines_material/Sonstiges/Programming/Python/Scripts/General/Plotting/auxiliary_plotting_functions.py in show_or_save_plot(fig, path, basename, file_extensions, dpi, legend, bbox_inches, transparent, legend_is_inside, remove_surrounding_whitespace, use_plotly, plotly_show_renderer, plotly_default_template, plotly_axlabel_size, plotly_title_label_size, plotly_font_family, plotly_font_color, linux_dir_sep, save_plotting_data_to_plain_text_AS_WELL, save_plotting_data_to_plain_text_ONLY)
   3549 
   3550         # Carry out the saving procedure building up on the save-fig function
-> 3551         save_figs(path,
   3552                   fig=fig,
   3553                   file_extensions=file_extensions,

~/Dokumente/Allgemeines_material/Sonstiges/Programming/Python/Scripts/General/Plotting/auxiliary_plotting_functions.py in save_figs(filename, fig, file_extensions, dpi, standard_dpi, legend, bbox_inches, transparent, remove_surrounding_whitespace, legend_is_inside, linux_dir_sep, use_plotly, plotly_default_template, plotly_axlabel_size, plotly_title_label_size, plotly_font_family, plotly_font_color, save_plotting_data_to_plain_text_AS_WELL, save_plotting_data_to_plain_text_ONLY)
   2395                     if not remove_surrounding_whitespace:
   2396                         # Call savefig-method pertaining to a pyplot-fig-object with its provided kwargs
-> 2397                         fig.savefig(filename + t,
   2398                                     dpi=dpi,
   2399                                     bbox_inches=bbox_inches,

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/figure.py in savefig(self, fname, transparent, **kwargs)
   2309                 patch.set_edgecolor('none')
   2310 
-> 2311         self.canvas.print_figure(fname, **kwargs)
   2312 
   2313         if transparent:

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/backend_bases.py in print_figure(self, filename, dpi, facecolor, edgecolor, orientation, format, bbox_inches, pad_inches, bbox_extra_artists, backend, **kwargs)
   2191                            else suppress())
   2192                     with ctx:
-> 2193                         self.figure.draw(renderer)
   2194 
   2195                     bbox_inches = self.figure.get_tightbbox(

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/artist.py in draw_wrapper(artist, renderer, *args, **kwargs)
     39                 renderer.start_filter()
     40 
---> 41             return draw(artist, renderer, *args, **kwargs)
     42         finally:
     43             if artist.get_agg_filter() is not None:

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/figure.py in draw(self, renderer)
   1861 
   1862             self.patch.draw(renderer)
-> 1863             mimage._draw_list_compositing_images(
   1864                 renderer, self, artists, self.suppressComposite)
   1865 

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/image.py in _draw_list_compositing_images(renderer, parent, artists, suppress_composite)
    130     if not_composite or not has_images:
    131         for a in artists:
--> 132             a.draw(renderer)
    133     else:
    134         # Composite any adjacent images together

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/cbook/deprecation.py in wrapper(*inner_args, **inner_kwargs)
    409                          else deprecation_addendum,
    410                 **kwargs)
--> 411         return func(*inner_args, **inner_kwargs)
    412 
    413     return wrapper

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/cbook/deprecation.py in wrapper(*inner_args, **inner_kwargs)
    409                          else deprecation_addendum,
    410                 **kwargs)
--> 411         return func(*inner_args, **inner_kwargs)
    412 
    413     return wrapper

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/projections/polar.py in draw(self, renderer, *args, **kwargs)
    993             self.yaxis.set_clip_path(self.patch)
    994 
--> 995         Axes.draw(self, renderer, *args, **kwargs)
    996 
    997     def _gen_axes_patch(self):

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/artist.py in draw_wrapper(artist, renderer, *args, **kwargs)
     39                 renderer.start_filter()
     40 
---> 41             return draw(artist, renderer, *args, **kwargs)
     42         finally:
     43             if artist.get_agg_filter() is not None:

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/cbook/deprecation.py in wrapper(*inner_args, **inner_kwargs)
    409                          else deprecation_addendum,
    410                 **kwargs)
--> 411         return func(*inner_args, **inner_kwargs)
    412 
    413     return wrapper

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/axes/_base.py in draw(self, renderer, inframe)
   2746             renderer.stop_rasterizing()
   2747 
-> 2748         mimage._draw_list_compositing_images(renderer, self, artists)
   2749 
   2750         renderer.close_group('axes')

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/image.py in _draw_list_compositing_images(renderer, parent, artists, suppress_composite)
    130     if not_composite or not has_images:
    131         for a in artists:
--> 132             a.draw(renderer)
    133     else:
    134         # Composite any adjacent images together

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/artist.py in draw_wrapper(artist, renderer, *args, **kwargs)
     39                 renderer.start_filter()
     40 
---> 41             return draw(artist, renderer, *args, **kwargs)
     42         finally:
     43             if artist.get_agg_filter() is not None:

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/axis.py in draw(self, renderer, *args, **kwargs)
   1167 
   1168         for tick in ticks_to_draw:
-> 1169             tick.draw(renderer)
   1170 
   1171         # scale up the axis label box to also find the neighbors, not

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/artist.py in draw_wrapper(artist, renderer, *args, **kwargs)
     39                 renderer.start_filter()
     40 
---> 41             return draw(artist, renderer, *args, **kwargs)
     42         finally:
     43             if artist.get_agg_filter() is not None:

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/axis.py in draw(self, renderer)
    289         for artist in [self.gridline, self.tick1line, self.tick2line,
    290                        self.label1, self.label2]:
--> 291             artist.draw(renderer)
    292         renderer.close_group(self.__name__)
    293         self.stale = False

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/artist.py in draw_wrapper(artist, renderer, *args, **kwargs)
     39                 renderer.start_filter()
     40 
---> 41             return draw(artist, renderer, *args, **kwargs)
     42         finally:
     43             if artist.get_agg_filter() is not None:

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/text.py in draw(self, renderer)
    695 
    696             gc = renderer.new_gc()
--> 697             gc.set_foreground(textobj.get_color())
    698             gc.set_alpha(textobj.get_alpha())
    699             gc.set_url(textobj._url)

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/backend_bases.py in set_foreground(self, fg, isRGBA)
    953             self._rgb = fg
    954         else:
--> 955             self._rgb = colors.to_rgba(fg)
    956 
    957     def set_joinstyle(self, js):

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/colors.py in to_rgba(c, alpha)
    187         rgba = None
    188     if rgba is None:  # Suppress exception chaining of cache lookup failure.
--> 189         rgba = _to_rgba_no_colorcycle(c, alpha)
    190         try:
    191             _colors_full_map.cache[c, alpha] = rgba

/home/linuxbrew/.linuxbrew/lib/python3.8/site-packages/matplotlib/colors.py in _to_rgba_no_colorcycle(c, alpha)
    261     # tuple color.
    262     if not np.iterable(c):
--> 263         raise ValueError(f"Invalid RGBA argument: {orig_c!r}")
    264     if len(c) not in [3, 4]:
    265         raise ValueError("RGBA sequence should have length 3 or 4")

ValueError: Invalid RGBA argument: None

正如@JohanC 指出的那样,将 None 传递给 set_yticklabelscolor-kwarg 导致了 违反直觉的错误消息 我的问题。

避免 None 成功了,现在有效了。

为了安全起见,我编写了一个函数,避免将 None 传递给所涉及的任何 key-value 个参数(“kwargs”),可以在下面找到。

这是为了自动化一切,避免在每个需要彩色标签的绘图函数中编码过多。 该功能包括标记坐标轴、标题和颜色条的情况。

def set_ticklabels_or_title_of_current_ax(ax_or_cbar=None,
                                          labels=None,
                                          label_type=None,
                                          ax_title_pos=(0.5, 0.985),
                                          label_color=None,
                                          font_weight=None,
                                          special_textfont_size=None):
    """Function docs:\n
    Avoid too much code in the main plotting function.

    # NOTE on scope: not all of them are accepted as None since they could override the initial value
    # Docs: https://whosebug.com/questions/63245556/valueerror-invalid-rgba-argument-none-when-plotting-via-matplotlib-ax-bar?noredirect=1#comment111839077_63245556
    """

    # Check tick type passed
    if label_type is None:
        raise Exception("The user must pass a tick type (x or y).")

    # Check whether an axis has been passed by the user
    if ax_or_cbar is None and label_type.lower() in [
            "x", "x-axis", "y", "y-axis", "title"
    ]:
        ax_or_cbar = plt.gca()

    # In the case that all variables were passed as None, return the axis unchanged
# NOTE: the function used here "check_if_any_or_all_of_the_passed_vars_are_None()" is a custom function, not included here: can be ignored
    if tools.check_if_any_or_all_of_the_passed_vars_are_None(
        [label_color, font_weight, special_textfont_size],
            raise_error_within_function=False,
            any_is_None=False):
        # Return the ax unchanged
        return ax_or_cbar

    # * Check if labels were passed * #
    if labels is None:
        if label_type.lower() in ["x", "x-axis"]:
            labels = [elem.get_text() for elem in list(ax_or_cbar.get_xticklabels())]
        elif label_type.lower() in ["y", "y-axis"]:
            labels = [elem.get_text() for elem in list(ax_or_cbar.get_yticklabels())]
        elif label_type.lower() in ["title", "cbar title"]:
            raise Exception("No title label has been passed.")
        elif label_type.lower() in [
                "cbar yticklabels", "cbar yticks", "cbar y"
        ]:
            labels = list(ax_or_cbar.ax.get_yticklabels())

    # * Check which variables were passed as None * #
    if label_color is not None and font_weight is not None and special_textfont_size is not None:
        if label_type.lower() in ["x", "x-axis"]:
            ax_or_cbar.set_xticklabels(labels,
                                       color=label_color,
                                       weight=font_weight,
                                       fontsize=special_textfont_size)
        elif label_type.lower() in ["y", "y-axis"]:
            ax_or_cbar.set_yticklabels(labels,
                                       color=label_color,
                                       weight=font_weight,
                                       fontsize=special_textfont_size)
        elif label_type.lower() == "title":
            ax_or_cbar.set_title(labels,
                                 position=ax_title_pos,
                                 color=label_color,
                                 weight=font_weight,
                                 fontsize=special_textfont_size)
        elif label_type.lower() == "cbar title":
            ax_or_cbar.set_label(labels,
                           color=label_color,
                           weight=font_weight,
                           fontsize=special_textfont_size)
        elif label_type.lower() in [
                "cbar yticklabels", "cbar yticks", "cbar y"
        ]:
            ax_or_cbar.ax.set_yticklabels(labels,
                                          color=label_color,
                                          weight=font_weight,
                                          fontsize=special_textfont_size)

    elif label_color is not None and font_weight is not None and special_textfont_size is None:
        if label_type.lower() in ["x", "x-axis"]:
            ax_or_cbar.set_xticklabels(labels,
                                       color=label_color,
                                       weight=font_weight)
        elif label_type.lower() in ["y", "y-axis"]:
            ax_or_cbar.set_yticklabels(labels,
                                       color=label_color,
                                       weight=font_weight)
        elif label_type.lower() == "title":
            ax_or_cbar.set_title(labels,
                                 position=ax_title_pos,
                                 color=label_color,
                                 weight=font_weight)
        elif label_type.lower() == "cbar title":
            ax_or_cbar.set_label(labels, color=label_color, weight=font_weight)
        elif label_type.lower() in [
                "cbar yticklabels", "cbar yticks", "cbar y"
        ]:
            ax_or_cbar.ax.set_yticklabels(labels,
                                          color=label_color,
                                          weight=font_weight)

    elif label_color is not None and font_weight is None and special_textfont_size is not None:
        if label_type.lower() in ["x", "x-axis"]:
            ax_or_cbar.set_xticklabels(labels,
                                       color=label_color,
                                       fontsize=special_textfont_size)
        elif label_type.lower() in ["y", "y-axis"]:
            ax_or_cbar.set_yticklabels(labels,
                                       color=label_color,
                                       fontsize=special_textfont_size)
        elif label_type.lower() == "title":
            ax_or_cbar.set_title(labels,
                                 position=ax_title_pos,
                                 color=label_color,
                                 fontsize=special_textfont_size)
        elif label_type.lower() == "cbar title":
            ax_or_cbar.set_label(labels,
                           color=label_color,
                           fontsize=special_textfont_size)
        elif label_type.lower() in [
                "cbar yticklabels", "cbar yticks", "cbar y"
        ]:
            ax_or_cbar.ax.set_yticklabels(labels,
                                          color=label_color,
                                          fontsize=special_textfont_size)

    elif label_color is None and font_weight is not None and special_textfont_size is not None:
        if label_type.lower() in ["x", "x-axis"]:
            ax_or_cbar.set_xticklabels(labels,
                                       weight=font_weight,
                                       fontsize=special_textfont_size)
        elif label_type.lower() in ["y", "y-axis"]:
            ax_or_cbar.set_yticklabels(labels,
                                       weight=font_weight,
                                       fontsize=special_textfont_size)
        elif label_type.lower() == "title":
            ax_or_cbar.set_title(labels,
                                 position=ax_title_pos,
                                 weight=font_weight,
                                 fontsize=special_textfont_size)
        elif label_type.lower() == "cbar title":
            ax_or_cbar.set_label(labels,
                           weight=font_weight,
                           fontsize=special_textfont_size)
        elif label_type.lower() in [
                "cbar yticklabels", "cbar yticks", "cbar y"
        ]:
            ax_or_cbar.ax.set_yticklabels(labels,
                                          weight=font_weight,
                                          fontsize=special_textfont_size)

    elif label_color is None and font_weight is None and special_textfont_size is not None:
        if label_type.lower() in ["x", "x-axis"]:
            ax_or_cbar.set_xticklabels(labels, fontsize=special_textfont_size)
        elif label_type.lower() in ["y", "y-axis"]:
            ax_or_cbar.set_yticklabels(labels, fontsize=special_textfont_size)
        elif label_type.lower() == "title":
            ax_or_cbar.set_title(labels,
                                 position=ax_title_pos,
                                 fontsize=special_textfont_size)
        elif label_type.lower() == "cbar title":
            ax_or_cbar.set_label(labels, fontsize=special_textfont_size)
        elif label_type.lower() in [
                "cbar yticklabels", "cbar yticks", "cbar y"
        ]:
            ax_or_cbar.ax.set_yticklabels(labels,
                                          fontsize=special_textfont_size)

    elif label_color is None and font_weight is not None and special_textfont_size is None:
        if label_type.lower() in ["x", "x-axis"]:
            ax_or_cbar.set_xticklabels(labels, weight=font_weight)
        elif label_type.lower() in ["y", "y-axis"]:
            ax_or_cbar.set_yticklabels(labels, weight=font_weight)
        elif label_type.lower() == "title":
            ax_or_cbar.set_title(labels,
                                 position=ax_title_pos,
                                 weight=font_weight)
        elif label_type.lower() == "cbar title":
            ax_or_cbar.set_label(labels, weight=font_weight)
        elif label_type.lower() in [
                "cbar yticklabels", "cbar yticks", "cbar y"
        ]:
            ax_or_cbar.ax.set_yticklabels(labels, weight=font_weight)

    elif label_color is not None and font_weight is None and special_textfont_size is None:
        if label_type.lower() in ["x", "x-axis"]:
            ax_or_cbar.set_xticklabels(labels, color=label_color)
        elif label_type.lower() in ["y", "y-axis"]:
            ax_or_cbar.set_yticklabels(labels, color=label_color)
        elif label_type.lower() == "title":
            ax_or_cbar.set_title(labels,
                                 position=ax_title_pos,
                                 color=label_color)
        elif label_type.lower() == "cbar title":
            ax_or_cbar.set_label(labels, color=label_color)
        elif label_type.lower() in [
                "cbar yticklabels", "cbar yticks", "cbar y"
        ]:
            ax_or_cbar.ax.set_yticklabels(labels, color=label_color)

    # Return updated axis to user
    return ax_or_cbar