Solutions to class exercise

eth-vaw-glaciology · Sep 22, 2023 · 156464a · 156464a
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diff --git a/slide-notebooks/deploy_notebooks.jl b/slide-notebooks/deploy_notebooks.jl
@@ -2,7 +2,7 @@ using Literate
 ## include Literate scripts starting with following 3 letters in the deploy
 incl = "l1_"
 ## Set `sol=true` to produce output with solutions contained and hints stripts. Otherwise the other way around.
-sol = false
+sol = true
 ##
 
 function replace_string(str)

diff --git a/slide-notebooks/l1_3-julia-intro.jl b/slide-notebooks/l1_3-julia-intro.jl
@@ -215,7 +215,7 @@ Furthermore, documentation can be gotten with `?xyz`
 #src #########################################################################
 #nb # %% A slide [markdown] {"slideshow": {"slide_type": "slide"}}
 md"""
-## Variables, assignments, and types
+## Variables, assignments, and types [5min]
 [https://docs.julialang.org/en/v1/manual/variables/](https://docs.julialang.org/en/v1/manual/variables/)
 """
 
@@ -284,7 +284,7 @@ Dict("a"=>1, "b"=>cos)
 #src #########################################################################
 #nb # %% A slide [markdown] {"slideshow": {"slide_type": "slide"}}
 md"""
-### Array exercises
+## Array exercises [15min]
 
 We will use arrays extensively in this course.
 
@@ -501,7 +501,7 @@ The rest about Arrays you will learn-by-doing.
 #src #########################################################################
 #nb # %% A slide [markdown] {"slideshow": {"slide_type": "slide"}}
 md"""
-## Control flow
+## Control flow [10min]
 
 Julia provides a variety of [control flow constructs](https://docs.julialang.org/en/v1/manual/control-flow/), of which we look at:
 
@@ -604,14 +604,14 @@ end
 #src #########################################################################
 #nb # %% A slide [markdown] {"slideshow": {"slide_type": "slide"}}
 md"""
-## Functions
+## Functions [15min]
 
 Functions can be defined in Julia in a number of ways.  In particular there is one variant
 more suited to longer definitions, and one for one-liners:
 
 ```
 function f(a, b)
-   a * b
+   return a * b
 end
 f(a, b) = a * b
 ```
@@ -789,7 +789,7 @@ This is a key characteristic of the Julia package ecosystem.
 #src #########################################################################
 #nb # %% A slide [markdown] {"slideshow": {"slide_type": "slide"}}
 md"""
-## Modules and packages
+## Modules and packages [5min]
 
 Modules can be used to structure code into larger entities, and be used to divide it into
 different name spaces.  We will not make much use of those, but if interested see

diff --git a/slide-notebooks/notebooks/l1_3-julia-intro.ipynb b/slide-notebooks/notebooks/l1_3-julia-intro.ipynb
@@ -341,7 +341,7 @@
   {
    "cell_type": "markdown",
    "source": [
-    "## Variables, assignments, and types\n",
+    "## Variables, assignments, and types [5min]\n",
     "[https://docs.julialang.org/en/v1/manual/variables/](https://docs.julialang.org/en/v1/manual/variables/)"
    ],
    "metadata": {
@@ -478,7 +478,7 @@
   {
    "cell_type": "markdown",
    "source": [
-    "### Array exercises\n",
+    "## Array exercises [15min]\n",
     "\n",
     "We will use arrays extensively in this course.\n",
     "\n",
@@ -506,8 +506,8 @@
    "cell_type": "code",
    "source": [
     "a = [2, 3]\n",
-    "b = ...\n",
-    "[ ; ]"
+    "b = [4, 5]\n",
+    "[a ; b]"
    ],
    "metadata": {},
    "execution_count": null
@@ -523,7 +523,8 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "push!(b, 1)\n",
+    "push!(b, 3, 4)"
    ],
    "metadata": {},
    "execution_count": null
@@ -546,7 +547,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "[  ;  ]"
+    "[1:10; [4,5]]"
    ],
    "metadata": {},
    "execution_count": null
@@ -562,7 +563,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "a = rand(3,3)"
    ],
    "metadata": {},
    "execution_count": null
@@ -585,7 +586,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "a[ ... ], a[ ... ]"
+    "a[1,2], a[2,1]"
    ],
    "metadata": {},
    "execution_count": null
@@ -601,7 +602,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "[ a[1,2], a[2,1] ]"
    ],
    "metadata": {},
    "execution_count": null
@@ -635,8 +636,8 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "a[...]\n",
-    "a[..., ...]"
+    "a[end]\n",
+    "a[end, end]"
    ],
    "metadata": {},
    "execution_count": null
@@ -659,7 +660,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "a[... , ...]"
+    "a[end, 1:end]"
    ],
    "metadata": {},
    "execution_count": null
@@ -675,7 +676,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "a[ ]"
+    "a[1:2, 1:2]"
    ],
    "metadata": {},
    "execution_count": null
@@ -799,7 +800,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "@assert ..."
+    "@assert a[1] == 99"
    ],
    "metadata": {},
    "execution_count": null
@@ -858,7 +859,10 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "a = Int[]\n",
+    "push!(a, 1) ## works\n",
+    "push!(a, 1.0) ## works\n",
+    "push!(a, 1.5) ## errors as 1.5 cannot be converted to an Int"
    ],
    "metadata": {},
    "execution_count": null
@@ -875,7 +879,9 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "a = []\n",
+    "push!(a, 5)\n",
+    "push!(a, \"a\")"
    ],
    "metadata": {},
    "execution_count": null
@@ -891,7 +897,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "[1][1] = 1.5 ## errors"
    ],
    "metadata": {},
    "execution_count": null
@@ -915,7 +921,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "a = Array{Any}(undef, 3, 3)"
    ],
    "metadata": {},
    "execution_count": null
@@ -931,7 +937,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "size(a)"
    ],
    "metadata": {},
    "execution_count": null
@@ -953,7 +959,7 @@
   {
    "cell_type": "markdown",
    "source": [
-    "## Control flow\n",
+    "## Control flow [10min]\n",
     "\n",
     "Julia provides a variety of [control flow constructs](https://docs.julialang.org/en/v1/manual/control-flow/), of which we look at:\n",
     "\n",
@@ -999,7 +1005,14 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "a = \"Where are the flowers\"\n",
+    "if startswith(a, \"Wh\")\n",
+    "  b = \"Likely a question\"\n",
+    "elseif startswith(a, \"The\")\n",
+    "  b = \"Likely a noun\"\n",
+    "else\n",
+    "  b = \"no idea\"\n",
+    "end"
    ],
    "metadata": {},
    "execution_count": null
@@ -1031,7 +1044,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "a > 5 ? \"really big\" : \"not so big\""
    ],
    "metadata": {},
    "execution_count": null
@@ -1063,6 +1076,14 @@
    ],
    "metadata": {}
   },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "If `a < 0` evaluates to `true` then the bit after the `&&` is evaluated too,\n",
+    "i.e. an error is thrown.  Otherwise, only `a < 0` is evaluated and no error is thrown."
+   ],
+   "metadata": {}
+  },
   {
    "cell_type": "markdown",
    "source": [
@@ -1101,14 +1122,14 @@
   {
    "cell_type": "markdown",
    "source": [
-    "## Functions\n",
+    "## Functions [15min]\n",
     "\n",
     "Functions can be defined in Julia in a number of ways.  In particular there is one variant\n",
     "more suited to longer definitions, and one for one-liners:\n",
     "\n",
     "```\n",
     "function f(a, b)\n",
-    "   a * b\n",
+    "   return a * b\n",
     "end\n",
     "f(a, b) = a * b\n",
     "```\n",
@@ -1143,7 +1164,13 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "function fn(a, b)\n",
+    "  if a> b\n",
+    "    return a\n",
+    "  else\n",
+    "    return b\n",
+    "  end\n",
+    "end"
    ],
    "metadata": {},
    "execution_count": null
@@ -1169,7 +1196,8 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "mymap(fn, a) = [fn(aa) for aa in a]\n",
+    "mymap(sin, 1:10)"
    ],
    "metadata": {},
    "execution_count": null
@@ -1195,7 +1223,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "sin.(1:10)"
    ],
    "metadata": {},
    "execution_count": null
@@ -1212,7 +1240,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "(1:10) .+ (1:10)'"
    ],
    "metadata": {},
    "execution_count": null
@@ -1236,7 +1264,8 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "x,y = 0:0.1:pi, -pi:0.1:pi\n",
+    "sin.(x) .+ cos.(y')"
    ],
    "metadata": {},
    "execution_count": null
@@ -1264,7 +1293,7 @@
    "outputs": [],
    "cell_type": "code",
    "source": [
-    "#"
+    "map(x -> sin(x) + cos(x), 1:10)"
    ],
    "metadata": {},
    "execution_count": null
@@ -1406,7 +1435,7 @@
   {
    "cell_type": "markdown",
    "source": [
-    "## Modules and packages\n",
+    "## Modules and packages [5min]\n",
     "\n",
     "Modules can be used to structure code into larger entities, and be used to divide it into\n",
     "different name spaces.  We will not make much use of those, but if interested see\n",