00_solutions.py

# -*- coding: utf-8 -*-
"""00_solutions.py

Author -- Michael Widrich
Contact -- widrich@ml.jku.at
Date -- 01.10.2019

Add tasks 6, 7 by Van Quoc Phuong Huynh -- WS2020


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The following copyright statement applies to all code within this file.

Copyright statement:
This material, no matter whether in printed or electronic form, may be used for
personal and non-commercial educational use only. Any reproduction of this
manuscript, no matter whether as a whole or in parts, no matter whether in
printed or in electronic form, requires explicit prior acceptance of the
authors.

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Example solutions for tasks in file 00_tasks.py.

"""

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# 00 Variables
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#
# Task 1
#

# Create a variable 'a' with the content 1 and a variable 'b' with the
# content False.

# Your code here #
a = 1
b = False


#
# Task 2
#

# Convert the following variable 'a' into an integer. Take a look at the
# variable in the debugger. What will happen to the floating point number if
# it is converted to an integer?
a = 5.356

# Your code here #
a = int(a)
# Conversion from float to int means we lose the information after the
# floating point!


#
# Task 3
#

# Create a variable 'a' with content "test" and a variable 'b' that points
# to the same content as 'a'. Afterwards let 'a' point to 2 and delete 'b'.
# What will happen to the string "test" after deleting variable 'b'?

# Your code here #
a = "test"
b = a
a = 2
del b
# The garbage collector will at some point remove the string "test"
# because no variable is pointing to it anymore.


#
# Task 4
#

# Create a variable 'a' with content 123 and create a variable 'b'
# pointing to a string that consists of the sentence
# "this is a test " followed by the contents of variable 'a'.
# Finally, create a variable 'c' that repeats this sentence 3 times.

# Your code here #
a = 123
b = f"this is a test {a}"
c = b * 3


#
# Task 5
#

# Take a look at the following lines of code. Why does variable 'a' have a
# different value than variable 'b'?
# And which of the two version should be used if you need the precise value?

a = 123456789123456789
b = int(123456789123456789.0)
print(f"value a: {a}")
print(f"value b: {b}")

# For variable 'a', an integer is used, which is precise. Since Python3
# uses variable-length integers, we will not run out of bits to encode the
# value.
# For variable 'b' a float is used and then converted to an integer. However,
# the float 123456789123456789.0 can not be stored in the 64bit Python3
# float, so we lose precision and effectively end up with a different value.
# If you want the precise value, you should use the integer version.


#
# Task 6
#

# What are the data types of values referenced by variables 'a' and 'b'?
# What is the role of '_' among the digits
# Examine the syntax of formatting print for the content of 'a' and 'b'

a = 123_456_789.123_456_789
b = 123_456_789
print(f"a: {a}, formatted a: {a:,.4f}")
print(f"b: {b}, formatted b: {b:,d}")

# The data types of values referenced by variables 'a' and 'b' are float and integer, respectively.
# '_' underscores are just to make the numbers easier to read, they do not change the values.
# To print big numbers in a easy-to-read way, use following syntax in a formatted string (f""):
# {variable:,.<int number>f} for float numbers; Note: without space character after the comma
# {variable:,d} for integer number; Note: without space character after the comma


#
# Task 7
#

# You are given the time period of 1234567.789 seconds. Print this value with the format below as string:
# Time period: <int number> Days, <int number> Hours, <int number> Minutes, <float with 2 digits after point> Seconds

# Hint: You can solve this task by looking at remainders of divisions

# Your code here #
total_seconds = 1_234_567.789
seconds = total_seconds % 60  # get the remainder of a division with modulo operation
total_minutes = total_seconds // 60  # get the floor value of a division
minutes = total_minutes % 60
total_hours = total_minutes // 60
hours = total_hours % 24
total_days = total_hours // 24
print(f'Time period: {int(total_days)} Days, {int(hours)} Hours, {int(minutes)} Minutes, {seconds:,.2f} Seconds')