René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"ValueError: cannot convert float NaN to integer","articleBody":"### Bug report\r\n\r\n**Bug summary**\r\n\r\n\u003c!--A short 1-2 sentences that succinctly describes the bug--\u003e\r\n\r\n**Code for reproduction**\r\n\r\n```python\r\nimport matplotlib\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\n\r\nplt.rcParams['figure.figsize'] = 10,10\r\n\r\nclass MidpointNormalize(matplotlib.colors.Normalize):\r\n    def __init__(self, vmin=None, vmax=None, midpoint=None, clip=False):\r\n        self.midpoint = midpoint\r\n        matplotlib.colors.Normalize.__init__(self, vmin, vmax, clip)\r\n\r\n    def __call__(self, value, clip=None):\r\n        # Note that I'm ignoring clipping and other edge cases here.\r\n        result, is_scalar = self.process_value(value)\r\n        x, y = [self.vmin, self.midpoint, self.vmax], [0, 0.5, 1]\r\n        return np.ma.array(np.interp(value, x, y), mask=result.mask, copy=False)\r\n\r\n# make these smaller to increase the resolution\r\ndx, dy = 0.15, 0.05\r\n\r\n# generate 2 2d grids for the x \u0026 y bounds\r\ny, x = np.mgrid[slice(-3, 3 + dy, dy),\r\n                slice(-3, 3 + dx, dx)]\r\nz = (1 - x / 2. + x ** 5 + y ** 3) * np.exp(-x ** 2 - y ** 2)\r\n\r\nz = z[:-1, :-1]\r\nz_min, z_max = -np.abs(z).max(), np.abs(z).max()\r\nz [0:2,0:2] = np.nan\r\n\r\nplt.pcolormesh(x, y, z, cmap='seismic',norm=MidpointNormalize(midpoint=0.,vmin=-3,vmax=3))\r\nplt.title('pcolormesh')\r\nplt.axis([x.min(), x.max(), y.min(), y.max()])\r\nplt.colorbar(extend='min')\r\n\r\nplt.tight_layout(w_pad=0.1, h_pad=1)\r\nplt.savefig('test.png', dpi = 720)\r\n```\r\n\r\n**Actual outcome**\r\n\r\n\u003c!--The output produced by the above code, which may be a screenshot, console output, etc.--\u003e\r\n\r\n```\r\nE:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\colorbar.py:1042: RuntimeWarning: invalid value encountered in true_divide\r\n  z = np.take(y, i0) + (xn - np.take(b, i0)) * dy / db\r\nE:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\transforms.py:402: RuntimeWarning: invalid value encountered in double_scalars\r\n  return points[1, 0] - points[0, 0]\r\nTraceback (most recent call last):\r\n  File \"C:\\Users\\Xin\\Desktop\\test_extend.py\", line 37, in \u003cmodule\u003e\r\n    plt.savefig('test.png', dpi = 720)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\pyplot.py\", line 689, in savefig\r\n    res = fig.savefig(*args, **kwargs)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\figure.py\", line 2094, in savefig\r\n    self.canvas.print_figure(fname, **kwargs)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\backend_bases.py\", line 2075, in print_figure\r\n    **kwargs)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\backends\\backend_agg.py\", line 510, in print_png\r\n    FigureCanvasAgg.draw(self)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\backends\\backend_agg.py\", line 402, in draw\r\n    self.figure.draw(self.renderer)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\artist.py\", line 50, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\figure.py\", line 1649, in draw\r\n    renderer, self, artists, self.suppressComposite)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\image.py\", line 138, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\artist.py\", line 50, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\axes\\_base.py\", line 2628, in draw\r\n    mimage._draw_list_compositing_images(renderer, self, artists)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\image.py\", line 138, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\artist.py\", line 50, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\axis.py\", line 1185, in draw\r\n    ticks_to_draw = self._update_ticks(renderer)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\axis.py\", line 1023, in _update_ticks\r\n    tick_tups = list(self.iter_ticks())  # iter_ticks calls the locator\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\axis.py\", line 967, in iter_ticks\r\n    majorLocs = self.major.locator()\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\ticker.py\", line 1985, in __call__\r\n    return self.tick_values(vmin, vmax)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\ticker.py\", line 1993, in tick_values\r\n    locs = self._raw_ticks(vmin, vmax)\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\ticker.py\", line 1932, in _raw_ticks\r\n    nbins = np.clip(self.axis.get_tick_space(),\r\n  File \"E:\\miniconda3\\envs\\satpy\\lib\\site-packages\\matplotlib\\axis.py\", line 2159, in get_tick_space\r\n    return int(np.floor(length / size))\r\nValueError: cannot convert float NaN to integer\r\n```\r\n\r\n**Expected outcome**\r\n\r\n![image](https://user-images.githubusercontent.com/30388627/63422517-1243e780-c43d-11e9-8577-095ff914b576.png)\r\n\r\n**Tmp solution**\r\nAdd the min and max of z to `vmin` and `vmax`:\r\n```\r\nplt.pcolormesh(x, y, z, vmin=z_min, vmax=z_max, cmap='seismic',norm=MidpointNormalize(midpoint=0.,vmin=-3,vmax=3))\r\n```\r\n\r\nHowever, it doesn't work if the vmin or vmax is beyond that:\r\n```\r\nplt.pcolormesh(x, y, z, vmin=-2, vmax=z_max, cmap='seismic',norm=MidpointNormalize(midpoint=0.,vmin=-3,vmax=3))\r\n```\r\n\r\n**Matplotlib version**\r\n\u003c!--Please specify your platform and versions of the relevant libraries you are using:--\u003e\r\n  * Operating system: Win 10\r\n  * Matplotlib version: 3.0.3 (conda-forge)\r\n  * Matplotlib backend: TkAgg\r\n  * Python version: 3.6.7","author":{"url":"https://github.com/zxdawn","@type":"Person","name":"zxdawn"},"datePublished":"2019-08-21T10:01:29.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/15093/matplotlib/issues/15093"}