Voluntary homework
The following exercises – except Exercise 0, see below – are voluntary. They cover the content of the first and second part of this course. Depending on our progress in part I, please try to solve only those exercises of the chapters we have discussed so far. Feel free to solve all exercises in the Spyder editor in separate scripts or in a Jupyter notebook.
If not already done during the course, please do Exercise 0 as we need the additional Python in part II.
Exercise 0 (Anaconda package management)
Please, install the pingouin package as well as all other packages listed in Chapter 2 via the Anaconda package manager (if not already done). Hint: Make sure that you have added the conda-forge channel.
Exercise 1 (“starter”)
As a “starter”, please play around with the following operators in the Spyder console. Apply the operators to numbers directly, but also work with variables.
Operator | Description |
---|---|
+ , - , * , / |
addition, subtraction, multiplication, division |
// |
integer division |
% |
modulo (“rest” of a division) |
-x , +x |
sign |
** |
exponentiation |
Operator | Description |
---|---|
< , > , <= , >= |
comparison operators is smaller/equal? bigger/equal? |
== |
comparison operator is equal? |
!= |
comparison operator is not equal? |
or , and , not |
boolean comparison operators |
in |
is element of? |
Exercise 2 (lists)
- Create two lists
A
andB
, withA
containing the numbers 7, 8, 9, andB
containing the numbers 17, 18, 19. - Apply to the second element of
A
and the third element ofB
some of the operators listed above. - Use the built-in Python command
sum()
to calculate and print the sum ofA
andB
, respectively.
# example solution output:
sum of A: 24
sum of B: 54
Toggle solution
Exercise 3 (using the script)
In this exercise we recap Chapter 7: for loops and train the scripting with the Spyder editor.
- In the Spyder editor, create a new Python script, e.g., called
for_loops.py
. - Transfer your or the given solution of Exercise 1 into that script. Put the solution into its own cell.
- Do the same for Exercise 2 and the “Example with enumerate command” of Section 3 The enumerate function.
- Run your script at once and each cell individually.
Exercise 4 (dictionaries)
- Create a new script in the Spyder editor.
- Define the dictionary
mouse
as presented in Chapter 4 Variables. - Expand
mouse
by the new key “owner”. Set as value your name.
Note: You don’t have to redefine the entire dictionary. You can add any new entry bymouse["new key"]=value
. - Add another entry “blood pressure” with values 80, 75, 95, 180.
- Instead of printing out the value of each key manually, write a for-loop, that iterates over all keys and prints out the corresponding value.
Hint: Withmouse.keys()
you get an iterable list of all keys (=sequence). - Create a
mouse2
dictionary by performing the same steps as in 1. This time, set the age to 38, the ID to 38979 and the weight to 37. Calculate the average age of both mice.
# example solution output:
SOLUTION 4.2-4.3:
{'ID': 45768,
'MWM_scores': [59, 50, 40, 27, 14, 11],
'age': 42,
'owner': 'My Name is Fabrizio',
'sex': 'male',
'weight': 36}
SOLUTION 4.4:
{'ID': 45768,
'MWM_scores': [59, 50, 40, 27, 14, 11],
'age': 42,
'blood pressure': [80, 75, 95, 180],
'owner': 'My Name is Fabrizio',
'sex': 'male',
'weight': 36}
SOLUTION 4.5:
ID: 45768
age: 42
sex: male
weight: 36
MWM_scores: [59, 50, 40, 27, 14, 11]
owner: My Name is Fabrizio
blood pressure: [80, 75, 95, 180]
SOLUTION 4.6:
40.0
Toggle solution
Exercise 5 (for-loops and if-statements)
Given the list agents=["James Bond (007)", "Austin Powers (007)", "Hubert Bonisseur, (117)"]
, write a for-loop, that iterates over each of its elements and checks, if the current agent has a 007-license. Again, create a new Spyder script with an appropriate name for your solution.
# example solution output:
James Bond (007)
match! James Bond (007) has a 007 license.
Austin Powers (007)
match! Austin Powers (007) has a 007 license.
Hubert Bonisseur, (117)
warning! Hubert Bonisseur, (117) has no 007 license!
Toggle solution
Exercise 6 (for-loops and the enumerate
function)
Chapter 5 for loops contains a section about creating a for-loop via the enumerate
function.
- Please, read this section.
- Create a new script in the Spyder editor.
- Create a number list
number_list
that ranges from 3 to 13 in the step-size of 1.
Hint: Use therange()
andlist()
command. - Write a for-loop, that iterates over
number_list
and prints out each element entry-by-entry and its accoriding index, by using theenumerate
function.
# example solution output:
number_list: [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
the length of number_list: 10
index 0 has the value 3
index 1 has the value 4
index 2 has the value 5
index 3 has the value 6
index 4 has the value 7
index 5 has the value 8
index 6 has the value 9
index 7 has the value 10
index 8 has the value 11
index 9 has the value 12
Toggle solution
Exercise 7 (for-loops and lists)
- Create a new script in the Spyder editor.
- Define the two lists:
A = [101, 102, 103, 104] B = [ 10, 12, 13, 14]
- Write a for-loop that iterates over the range of the length of one of the two lists. Inside the loop, print out the iterative result of the element-by-element multiplication of
A
andB
.
# example solution output:
i=0: A_i*B_i = 1010
i=1: A_i*B_i = 1224
i=2: A_i*B_i = 1339
i=3: A_i*B_i = 1456
Toggle solution
Exercise 8 (for-loops)
Given the list number_list_1=[4, 8, 12, 16, 20, 24, 28, 32]
, write in new Spyder script that prints out only elements of number_list_1
at even index positions.
# example solution output:
index: 0 (even) --> number 4
index: 2 (even) --> number 12
index: 4 (even) --> number 20
index: 6 (even) --> number 28
Toggle solution
Exercise 9 (functions)
Write a function print_name
, that prints out a given input name.
# example solution output:
The input name is: Fabrizio.
Toggle solution
Exercise 10 (functions)
Given the list number_list_0=[4, 8, 3, 9]
, write a function my_average(input_list)
(again, in a new script), that calculates and prints its average
with $x_i$ the individual elements of number_list_0
.
Hints:
- Use the
len()
command to determine the number of elements ($N$); - To calculate the sum, use a for-loop; within the for-loop, update a dummy sum variable (e.g.,
sum_runner
) for every iteration (e.g.,sum_runner = sum_runner + "new_value"
); if you want to use this approach, you have to pre-initializesum_runner = 0
before the loop.
# example solution output:
mean: 6.0
Toggle solution
Exercise 11 (functions)
Write a function product
, that multiplies all numbers of a given number list. Apply your function to the list list1=[4, 8, 12, 16, 20, 32, 28, 24, -1]
.
# example solution output:
2642411520
Toggle solution
Exercise 12 (functions)
Write a function calc_max
, that finds the maximum value and it index of a given list. Apply your function to the list defined in Exercise 11.
# example solution output:
the maximum of [4, 8, 12, 16, 20, 32, 28, -24, -1] is 32 at index 5
Toggle solution
Exercise 13 (deep vs. shallow copy)
- Given the list
A = [9, 27, 1, 8, 77]
. Create a copy ofA
into a new variable calledB
. Change the 3rd entry ofA
to-80
and print out both,A
andB
. What do you notice? - Please read the chapter about deep vs. shallow copy and apply appropriate changes to your script, so that a change of an element of
A
will no longer affect the entries inB
. Verify your adjustments by, again, changing the 3rd entry ofA
to-80
and printing outB
(that now should still show the initial defintion ofA
).
# example solution output:
initial A: [9, 27, 1, 8, 77]
created B: [9, 27, 1, 8, 77]
A after modifying A: [9, 27, -80, 8, 77]
B after modifying A: [9, 27, -80, 8, 77]
After applying appropriate changes:
initial A: [9, 27, 1, 8, 77]
created B: [9, 27, 1, 8, 77]
A after modifying A: [9, 27, -80, 8, 77]
B after modifying A: [9, 27, 1, 8, 77]
Toggle solution
The following exercises cover the content of part 2 of this course and can be voluntarily solved after the course’ end.
Exercise 14 (data I/O)
- Please visit this cheat sheet on Python Data I/O function and read the section about Built-in Python I/O functions.
- Write a script, that generates a new text file in write mode (
w
). - Iterate over the number 0 to 10 and write them line-by-line into the newly created file.
Hint: Use thestr()
command to convert an integer (or float) number into a string (if necessary). Also, use\n
within theprint()
command to force a line break after each entry input. - Save your results appropriately by closing the newly generate text file.
- Re-open the text file in read mode (
r
). - Write a for loop, that iterates over each line within the text file and prints out each individual entry.
- Don’t forget to close your file at the end.
# example solution output:
0
1
2
3
4
5
6
7
8
9
10
Toggle solution
Exercise 15 (NumPy)
Given the NumPy array A
,
A = np.array([np.arange(0,3,1)]*5,dtype='float16'),
write a script that
- prints out its shape,
- prints out all entries of column 1 and 2, separately and at once,
- overwrites the values of column 1 by the sum of the values of columns 2 and 3,
- replaces the entry of row 1, column 3 with its exponentiation with the factor 2,
Hint:x**2
. - replaces the entry of row 2, column 3 with the square root of the entry of row 2, column 0,
Hint: Please find the NumPy function for calculating the square root in the Useful NumPy functions list of Chapter 10: NumPy - Our data container. - prints out all entries with even index values of column 3, and
- calculates the average and standard deviation of all entries of column 3.
Hint: Again, please find the appropriate NumPy functions in the Useful NumPy functions list.
# example solution output:
SOLUTION 15.1:
A:
[[0. 1. 2.]
[0. 1. 2.]
[0. 1. 2.]
[0. 1. 2.]
[0. 1. 2.]]
A.shape: (5, 3)
SOLUTION 15.2:
[0. 0. 0. 0. 0.]
[1. 1. 1. 1. 1.]
[[0. 1.]
[0. 1.]
[0. 1.]
[0. 1.]
[0. 1.]]
SOLUTION 15.3:
[[3. 1. 2.]
[3. 1. 2.]
[3. 1. 2.]
[3. 1. 2.]
[3. 1. 2.]]
SOLUTION 15.4 and 15.5:
4.0
1.732
[[3. 1. 4. ]
[3. 1. 1.732]
[3. 1. 2. ]
[3. 1. 2. ]
[3. 1. 2. ]]
SOLUTION 15.6:
[4. 2. 2.]
SOLUTION 15.7:
the result: 2.345703125 +/- 0.83349609375