add some code created during last night demo

teuben · Jul 20, 2016 · 365ef38 · 365ef38
1 parent b62f020
commit 365ef38
Showing 1 changed file with 83 additions and 19 deletions.
diff --git a/notebooks/python-basic.ipynb b/notebooks/python-basic.ipynb
@@ -7,7 +7,7 @@
     "# Some Very Basic Python\n",
     "\n",
     "\n",
-    "Showing some very basic python: variables, printing, control structures, lists and arrays, math and plotting:\n",
+    "Showing some very basic ppython: variables, printing, control structures, lists and arrays, math and plotting:\n",
     "\n",
     "### Variables and printing them\n"
    ]
@@ -23,9 +23,11 @@
     "#  setting a variable in python uses dynamic typing\n",
     "a = 1.23\n",
     "\n",
+    "# in this cell, several python commands can be given. Execute this cell with \"SHIFT-ENTER\"\n",
+    "\n",
     "#  although just writing the variable will show it's value, but this is not the recommended\n",
     "#  way, because per cell only the last one will be printed and stored in the out[]\n",
-    "#  list that the notebook maintains\n",
+    "#  list that the notebook maintains, use the print() function for this, which we will see below.\n",
     "\n",
     "a\n",
     "a+1"
@@ -71,6 +73,7 @@
    "outputs": [],
    "source": [
     "\n",
+    "a=111\n",
     "a=\"1.23\"\n",
     "print(a,type(a))"
    ]
@@ -94,7 +97,7 @@
    },
    "outputs": [],
    "source": [
-    "# checking the value of the variable\n",
+    "# checking the value of the variable again\n",
     "a\n"
    ]
   },
@@ -130,7 +133,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Now we can **print(pi)** in python2.  The old style would be **print pi**"
+    "Now we can **print(pi)** in python2.  The old style would be **print pi**, which does not work in python3!"
    ]
   },
   {
@@ -161,7 +164,7 @@
    },
    "outputs": [],
    "source": [
-    "# for reference, here is the old style of printing in python2 \n",
+    "# for reference, here is the old style of printing in python2 if you want to uncomment this and try it out\n",
     "# print \"pi=\",pi"
    ]
   },
@@ -171,13 +174,13 @@
    "source": [
     "## Python Control structures\n",
     "\n",
-    "Most programming languages have a way to control the flow of the program. The common ones are\n",
+    "Most programming languages have a few common ways to control the flow of the program. The common ones in python are\n",
     "\n",
     "* if/then/else\n",
     "* for-loop\n",
     "* while-loop\n",
     "\n",
-    "While you are looking at this code, note that white-space (indentation) controls the extent of the code, and unlike other language, there is no special symbol or **end** type statement. This is probably the single most confusing thing about those new to the python language."
+    "While you are looking at this code, note that white-space (indentation) controls the extent of the code, and unlike other languages, there is no special **{}** symbol or **end** type statement. This forced indention is probably the single most confusing thing about those new to the python language."
    ]
   },
   {
@@ -234,10 +237,14 @@
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
-    "collapsed": true
+    "collapsed": false
    },
    "outputs": [],
-   "source": []
+   "source": [
+    "a=[1,2,3]\n",
+    "a[1]=22\n",
+    "print(a)\n"
+   ]
   },
   {
    "cell_type": "code",
@@ -262,10 +269,13 @@
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
-    "collapsed": true
+    "collapsed": false
    },
    "outputs": [],
-   "source": []
+   "source": [
+    "tuple(range(3))\n",
+    "\n"
+   ]
   },
   {
    "cell_type": "code",
@@ -275,9 +285,11 @@
    },
    "outputs": [],
    "source": [
-    "a1=range(3)\n",
-    "a2=range(1,4)\n",
-    "print(a1,a2)"
+    "a1=list(range(3))\n",
+    "a2=list(range(3,6))\n",
+    "print(a1,a2)\n",
+    "#a1=[0,1,2]\n",
+    "#a2=[3,4,5]"
    ]
   },
   {
@@ -291,6 +303,29 @@
     "a1+a2"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Python lists have some interesting slicing operators that allow you to take sub-lists. See if you can figure it out from the following examples:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "a=range(10)\n",
+    "print(a[2])\n",
+    "print(list(a[2:4]))\n",
+    "print(list(a[-2:]))\n",
+    "print(list(a[2:]))\n",
+    "print(list(a[:2]))"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -340,7 +375,8 @@
    },
    "outputs": [],
    "source": [
-    "a=np.arange(0,1,0.2)"
+    "a=np.arange(0,1,0.2)\n",
+    "a"
    ]
   },
   {
@@ -353,9 +389,20 @@
    "source": [
     "b = a*a\n",
     "c = np.sqrt(a)\n",
-    "print(a,b,c)"
+    "print(a)\n",
+    "print(b)\n",
+    "print(c)"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": []
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -364,9 +411,16 @@
    },
    "outputs": [],
    "source": [
-    "## now for some plotting, using matplotlib, neatly integrated with numpy arrays\n",
+    "# now for some plotting, using matplotlib, neatly integrated with numpy arrays\n",
+    "# we are going to plot the arrays we just created\n",
+    "\n",
+    "# these next two lines are optional, if you want a different backend\n",
+    "import matplotlib\n",
+    "matplotlib.use('agg')\n",
     "\n",
-    "# %matplotlib inline\n",
+    "# any command starting with % is special to ipython notebooks, it tells to produce plots inline,\n",
+    "# and not externally in a different graph (although that's fun too)\n",
+    "%matplotlib inline\n",
     "import matplotlib.pyplot as plt"
    ]
   },
@@ -404,6 +458,7 @@
    },
    "outputs": [],
    "source": [
+    "# plt.show() is only needed to finally plot on screen, in the case an external plot was to be produced\n",
     "plt.show()\n"
    ]
   },
@@ -447,7 +502,7 @@
    "source": [
     "# The bottom line\n",
     "\n",
-    "The python **out[]** list contains all the results from each cell. That may come in handy."
+    "The python **out[]** list contains all the results from each cell. That may come in handy. See what your notebook has produced so far!"
    ]
   },
   {
@@ -460,6 +515,15 @@
    "source": [
     "print(Out)"
    ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": []
   }
  ],
  "metadata": {