Fix errors in Bayesian Optimization Colab notebook

bayesian-optimization/bayesian_optimization.ipynb

@@ -16,13 +16,14 @@
     "try:\n",
     "    # Check if notebook is running in Google Colab\n",
     "    import google.colab\n",
+    "    !pip install matplotlib==3.1.3\n",
     "    # Get additional files from Github\n",
     "    !wget https://raw.githubusercontent.com/krasserm/bayesian-machine-learning/dev/bayesian-optimization/bayesian_optimization_util.py\n",
     "    # Install additional dependencies\n",
-    "    !pip install scikit-optimize==0.5.2\n",
-    "    !pip install GPy==1.9.8\n",
-    "    !pip install GPyOpt==1.2.1\n",
-    "    !pip install xgboost==0.90\n",
+    "    !pip install scikit-optimize==0.9.0\n",
+    "    !pip install GPy==1.10.0\n",
+    "    !pip install GPyOpt==1.2.6\n",
+    "    !pip install xgboost==1.7.2\n",
     "except:\n",
     "    pass"
    ]
@@ -245,7 +246,7 @@
     "    \n",
     "    def min_obj(X):\n",
     "        # Minimization objective is the negative acquisition function\n",
-    "        return -acquisition(X.reshape(-1, dim), X_sample, Y_sample, gpr)\n",
+    "        return -acquisition(X.reshape(-1, dim), X_sample, Y_sample, gpr).flatten()\n",
     "    \n",
     "    # Find the best optimum by starting from n_restart different random points.\n",
     "    for x0 in np.random.uniform(bounds[:, 0], bounds[:, 1], size=(n_restarts, dim)):\n",
@@ -695,4 +696,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 2
-}
+}