Modified the MA plot task slightly

Author: merenlin

bio-visualization-lab.ipynb

@@ -127,8 +127,10 @@
    "metadata": {},
    "source": [
     "There are many different methods of computing the average expression level(A) between the two observations and\n",
-    "the mean variation(M). To keep things simple, for this example we will just compare the sum on the x-axis vs the minus on the y-axis.\n",
-    "Our data is already normalized and preprocessed, so this will be enough to find the clear outliers. \n"
+    "the mean variation(M). To keep things simple, for this example we will just compare the mean avg on the x-axis vs the minus on the y-axis.\n",
+    "Our data is already normalized and preprocessed, so this will be enough to find the clear outliers. \n",
+    "\n",
+    "Don't forget to plot on the log scales on both axis."
    ]
   },
   {
@@ -142,8 +144,9 @@
     "import matplotlib.pyplot as plt\n",
     "%matplotlib inline\n",
     "\n",
-    "#A = df_MA['...'] + df_MA['...']\n",
-    "#M = df_MA['...'] - df_MA['...']\n",
+    "#A = x + y/2\n",
+    "#M = x - y\n",
+    "\n",
     "\n",
     "#Plot a scatter plot of M vs A"
    ]