Add several exercises for the list comprehensions.

1 files changed, 164 insertions, 0 deletions

diff --git a/advanced_python/17_list_comprehensions.ipyml b/advanced_python/17_list_comprehensions.ipyml
index a300331..cb5434f 100644
--- a/advanced_python/17_list_comprehensions.ipyml
+++ b/advanced_python/17_list_comprehensions.ipyml
@@ -202,7 +202,171 @@ cells:
     slideshow:
       slide_type: slide
 
+- markdown: |
+    ## Exercise: even number list comprehension
+
+    Write a simple list comprehension that generates the first 5 even
+    numbers as a list.
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- code: |
+    [2*i for i in range(1, 6)]
+
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- markdown: |
+    ## Exercise: positive `sin` values
+
+    Write a list comprehension that generates only positive values of the
+    `math.sin` when applied to the first 10 values between $0$ to $2 \pi$.
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- code: |
+    from math import sin, pi
+    [sin(i*2*pi) for i in range(0, 10) if sin(i*2*pi) > 0]
+
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- code: |
+    # or
+    r = [sin(i*2*pi) for i in range(0, 10)]
+    [x for x in r if x > 0]
+
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- markdown: |
+    ## Exercise: two letter permutations of 'hello'
+
+    Using a list comprehension, write all possible 2 letter permutations of
+    the word 'hello', do not worry about repetitions.
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- code: |
+    word = 'hello'
+    [x + y for x in word for y in word]
+
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- markdown: |
+    ## Exercise: unique two letter permutations of 'hello'
+
+    Write all possible 2 letter permutations of the word 'hello', this time
+    show only the unique ones.
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- code: |
+    word = 'hello'
+    set([x + y for x in word for y in word])
+
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- code: |
+    # Or better to use a generator expression
+    set(x + y for x in word for y in word)
+
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- markdown: |
+    ## Exercise: list of tuples
+
+    Using a list comprehension, create a list of tuples of the form `(x, x*x,
+    x*x*x)` for the first 5 integers starting at 1.
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- code: |
+    [(x, x*x, x*x*x) for x in range(1, 6)]
+
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- markdown: |
+    ## Exercise: simple dictionary comprehension
+
+    Create a dictionary with the keys being the lowercase characters of the
+    English alphabet and the value being an empty list.
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- code: |
+    {x: [] for x in 'abcdefghijklmnopqrstuvwxyz'}
+
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- markdown: |
+    ## Exercise: another simple dict comprehension
+
+    Create a dictionary with the keys being the lowercase words (only the
+    first three characters) denoting the day of the week and the value being
+    an integer corresponding to each with 0 being 'mon' and 6 'sun'.
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- code: |
+    {x: i for i, x in enumerate('mon', 'tue', 'wed', 'thu', 'fri', 'sat', 'sun') }
+
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- code: |
+    # Or
+    {x: i for i, x in enumerate('mon tue wed thu fri sat sun'.split()) }
+
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- markdown: |
+    ## Exercise: max `sin` generator expression
+
+    Using a generator expression find the maximum value of `math.sin` when
+    applied to the first 100 values between $0$ to $2 \pi$.
 
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- code: |
+    from math import sin, pi
+    max(sin(i*2*pi) for i in range(0, 100))
+
+  metadata:
+    slideshow:
+      slide_type: fragment
 
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