[08] make plot compatible with new matplotlib version

plt.hist() not working with plt.annotate() using arrow dicts
with newest matplotlib version

Author: thempel

notebooks/08-common-problems.ipynb

@@ -79,8 +79,10 @@
     "    if ax is None:\n",
     "        fig, ax = plt.subplots()\n",
     "    for n, _traj in enumerate(data):\n",
-    "        ax.hist(_traj, bins=30, alpha=.33, density=True, color='C{}'.format(n));\n",
-    "    ylims = ax.get_ylim()\n",
+    "        h, e = np.histogram(_traj, bins=30, density=True)\n",
+    "        ax.fill_between(e[1:], h, step='pre', alpha=.33, color='C{}'.format(n))\n",
+    "    \n",
+    "    ylims = (0, ax.get_ylim()[1])\n",
     "    xlims = ax.get_xlim()\n",
     "    for n, _traj in enumerate(data):\n",
     "        ax.plot(\n",
@@ -98,6 +100,7 @@
     "    ax.text(0.86 * xlims[1], 0.5 * ylims[1], '$x(time)$', ha='left', va='center', rotation=90)\n",
     "    ax.set_xlabel('TICA coordinate')\n",
     "    ax.set_ylabel('histogram counts & trajectory time')\n",
+    "    ax.set_ylim(0, ax.get_ylim()[1])  # fill_between resets lower ylim < 0\n",
     "    ax.legend(loc=2)"
    ]
   },
@@ -905,7 +908,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.5"
+   "version": "3.6.6"
   },
   "toc": {
    "base_numbering": 1,