2-more_exercises

2-more_exercises October 3, 2023 1 Python review: More exercises This notebook continues the review of Python basics. A key concept is that of a nested data struc- ture. For example, the first code cell will define a 2-D "array" as a list of lists. In [1]: % load_ext autoreload % autoreload 2 Consider the following dataset of exam grades, organized as a 2-D table and stored in Python as a "list of lists" under the variable name, grades . In [2]: grades = [ # First line is descriptive header. Subsequent lines hold data [ ' Student ' , ' Exam 1 ' , ' Exam 2 ' , ' Exam 3 ' ], [ ' Thorny ' , ' 100 ' , ' 90 ' , ' 80 ' ], [ ' Mac ' , ' 88 ' , ' 99 ' , ' 111 ' ], [ ' Farva ' , ' 45 ' , ' 56 ' , ' 67 ' ], [ ' Rabbit ' , ' 59 ' , ' 61 ' , ' 67 ' ], [ ' Ursula ' , ' 73 ' , ' 79 ' , ' 83 ' ], [ ' Foster ' , ' 89 ' , ' 97 ' , ' 101 ' ] ] grades Out[2]: [[ ' Student ' , ' Exam 1 ' , ' Exam 2 ' , ' Exam 3 ' ], [ ' Thorny ' , ' 100 ' , ' 90 ' , ' 80 ' ], [ ' Mac ' , ' 88 ' , ' 99 ' , ' 111 ' ], [ ' Farva ' , ' 45 ' , ' 56 ' , ' 67 ' ], [ ' Rabbit ' , ' 59 ' , ' 61 ' , ' 67 ' ], [ ' Ursula ' , ' 73 ' , ' 79 ' , ' 83 ' ], [ ' Foster ' , ' 89 ' , ' 97 ' , ' 101 ' ]] Exercise 0 ( students_test : 1 point). Complete the function get_students which takes a nested list grades as a parameter and reutrns a new list, students , which holds the names of the students as they from "top to bottom" in the table. - Note : the parameter grades will be similar to the table above in structure, but the data will be different. 1

In [3]: def get_students (grades): ### ### YOUR CODE HERE ### students = [item[ 0 ] for item in grades] del students[ 0 ] new_list = students return new_list The demo cell below should display [ ' Thorny ' , ' Mac ' , ' Farva ' , ' Rabbit ' , ' Ursula ' , ' Foster ' ] . In [4]: students = get_students(grades) students Out[4]: [ ' Thorny ' , ' Mac ' , ' Farva ' , ' Rabbit ' , ' Ursula ' , ' Foster ' ] The test cell below will check your solution against several randomly generated test cases. If your solution does not pass the test (or if you’re just curious), you can look at the variables used in the latest test run. They are automatically imported for you as part of the test. • input_vars - Dictionary containing all of the inputs to your function. Keys are the parameter names. • original_input_vars - Dictionary containing a copy of all the inputs to your function. This is useful for debugging failures related to your solution modifying the input. Keys are the parameter names. • returned_output_vars - Dictionary containing the outputs your function generated. If there are multiple outputs, the keys will match the names mentioned in the exercrise in- structions. • true_output_vars - Dictionary containing the outputs your function should have gener- ated. If there are multiple outputs, the keys will match the names mentioned in the exercrise instructions. All of the test cells in this notebook will use the same format, and you can expect a similar format on your exams as well. In [5]: # ` students_test ` : Test cell import nb_1_2_tester tester = nb_1_2_tester . Tester_1_2_0() for _ in range ( 20 ): try : tester . run_test(get_students) (input_vars, original_input_vars, returned_output_vars, true_output_vars) = tes except : (input_vars, original_input_vars, returned_output_vars, true_output_vars) = tes raise print ( ' Passed. Please submit! ' ) Passed. Please submit! 2

The demo cell below should display { ' Thorny ' : [100, 90, 80], ' Mac ' : [88, 99, 111], ' Farva ' : [45, 56, 67], ' Rabbit ' : [59, 61, 67], ' Ursula ' : [73, 79, 83], ' Foster ' : [89, 97, 101]} In [10]: grade_lists = build_grade_lists(grades) grade_lists Out[10]: { ' Thorny ' : [100, 90, 80], ' Mac ' : [88, 99, 111], ' Farva ' : [45, 56, 67], ' Rabbit ' : [59, 61, 67], ' Ursula ' : [73, 79, 83], ' Foster ' : [89, 97, 101]} In [11]: import nb_1_2_tester tester = nb_1_2_tester . Tester_1_2_2() for _ in range ( 20 ): try : tester . run_test(build_grade_lists) (input_vars, original_input_vars, returned_output_vars, true_output_vars) = te except : (input_vars, original_input_vars, returned_output_vars, true_output_vars) = te raise print ( ' Passed. Please submit! ' ) Passed. Please submit! Exercise 3 ( grade_dicts_test : 2 points). Complete the function build_grade_dicts , again taking grades as a parameter and returning new dictionary, grade_dicts , that maps names of students to dictionaries containing their scores. Each entry of this scores dictionary should be keyed on assignment name and hold the corresponding grade as an integer. For instance, grade_dicts[ ' Thorny ' ][ ' Exam 1 ' ] == 100 . You may find solutions to earlier exercises useful for completing this one. Feel free to use them! In [12]: def build_grade_dicts (grades): ### ### YOUR CODE HERE ### assignments = get_assignments(grades) grade_dicts = {} for L in grades[ 1 :]: grade_dicts[L[ 0 ]] = dict ( zip (assignments, [ int (g) for g in L[ 1 :]])) return grade_dicts 4

The demo cell below should display { ' Thorny ' : { ' Exam 1 ' : 100, ' Exam 2 ' : 90, ' Exam 3 ' : 80}, ' Mac ' : { ' Exam 1 ' : 88, ' Exam 2 ' : 99, ' Exam 3 ' : 111}, ' Farva ' : { ' Exam 1 ' : 45, ' Exam 2 ' : 56, ' Exam 3 ' : 67}, ' Rabbit ' : { ' Exam 1 ' : 59, ' Exam 2 ' : 61, ' Exam 3 ' : 67}, ' Ursula ' : { ' Exam 1 ' : 73, ' Exam 2 ' : 79, ' Exam 3 ' : 83}, ' Foster ' : { ' Exam 1 ' : 89, ' Exam 2 ' : 97, ' Exam 3 ' : 101}} In [13]: grade_dicts = build_grade_dicts(grades) grade_dicts Out[13]: { ' Thorny ' : { ' Exam 1 ' : 100, ' Exam 2 ' : 90, ' Exam 3 ' : 80}, ' Mac ' : { ' Exam 1 ' : 88, ' Exam 2 ' : 99, ' Exam 3 ' : 111}, ' Farva ' : { ' Exam 1 ' : 45, ' Exam 2 ' : 56, ' Exam 3 ' : 67}, ' Rabbit ' : { ' Exam 1 ' : 59, ' Exam 2 ' : 61, ' Exam 3 ' : 67}, ' Ursula ' : { ' Exam 1 ' : 73, ' Exam 2 ' : 79, ' Exam 3 ' : 83}, ' Foster ' : { ' Exam 1 ' : 89, ' Exam 2 ' : 97, ' Exam 3 ' : 101}} In [14]: import nb_1_2_tester tester = nb_1_2_tester . Tester_1_2_3() for _ in range ( 20 ): try : tester . run_test(build_grade_dicts) (input_vars, original_input_vars, returned_output_vars, true_output_vars) = te except : (input_vars, original_input_vars, returned_output_vars, true_output_vars) = te raise print ( ' Passed. Please submit! ' ) Passed. Please submit! Exercise 4 ( avg_grades_by_student_test : 1 point). Complete the function build_avg_by_student , taking grades as a parameter and returning a dictionary named avg_by_student that maps each student to his or her average exam score. For instance, avg_grades_by_student[ ' Thorny ' ] == 90 . You may find solutions to earlier exercises useful for completing this one. Feel free to use them! Hint. The statistics module of Python has at least one helpful function. In [15]: # Create a dict mapping names to grade averages. def build_avg_by_student (grades): ### ### YOUR CODE HERE ### grade_lists = build_grade_lists(grades) from statistics import mean return {n: mean(G) for n, G in grade_lists . items()} The demo cell below should display 5

{ ' Exam 1 ' : [100, 88, 45, 59, 73, 89], ' Exam 2 ' : [90, 99, 56, 61, 79, 97], ' Exam 3 ' : [80, 111, 67, 67, 83, 101]} In [19]: grades_by_assignment = build_grade_by_asn(grades) grades_by_assignment Out[19]: { ' Exam 1 ' : [100, 88, 45, 59, 73, 89], ' Exam 2 ' : [90, 99, 56, 61, 79, 97], ' Exam 3 ' : [80, 111, 67, 67, 83, 101]} In [20]: import nb_1_2_tester tester = nb_1_2_tester . Tester_1_2_5() for _ in range ( 20 ): try : tester . run_test(build_grade_by_asn) (input_vars, original_input_vars, returned_output_vars, true_output_vars) = te except : (input_vars, original_input_vars, returned_output_vars, true_output_vars) = te raise print ( ' Passed. Please submit! ' ) Passed. Please submit! Exercise 6 ( avg_grades_by_assignment_test : 1 point). Complete the function build_avg_by_asn , which takes grades as a parameter and returns a dictionary, avg_by_asn , which maps each exam to its average score. You may find solutions to earlier exercises useful for completing this one. Feel free to use them! In [21]: # Create a dict mapping items to average for that item across all students. def build_avg_by_asn (grades): ### ### YOUR CODE HERE ### from statistics import mean grades_by_assignment = build_grade_by_asn(grades) return {n: mean(G) for n, G in grades_by_assignment . items()} The demo cell below should display { ' Exam 1 ' : 75.66666666666667, ' Exam 2 ' : 80.33333333333333, ' Exam 3 ' : 84.83333333333333} In [22]: avg_grades_by_assignment = build_avg_by_asn(grades) avg_grades_by_assignment Out[22]: { ' Exam 1 ' : 75.66666666666667, ' Exam 2 ' : 80.33333333333333, ' Exam 3 ' : 84.83333333333333} 7

In [23]: import nb_1_2_tester tester = nb_1_2_tester . Tester_1_2_6() for _ in range ( 20 ): try : tester . run_test(build_avg_by_asn) (input_vars, original_input_vars, returned_output_vars, true_output_vars) = te except : (input_vars, original_input_vars, returned_output_vars, true_output_vars) = te raise print ( ' Passed. Please submit! ' ) Passed. Please submit! Exercise 7 ( rank_test : 2 points). Complete the function get_ranked_students which takes grades as an argument and returns a new list, ranked_students , which contains the names of students in order by decreasing score. That is, ranked_students[0] should contain the name of the top student (highest average exam score), and ranked_students[-1] should have the name of the bottom student (lowest average exam score). You may find solutions to earlier exercises useful for completing this one. Feel free to use them! In [24]: def get_ranked_students (grades): ### ### YOUR CODE HERE ### rank = [name for name in sorted (avg_grades_by_student, key = avg_grades_by_student . g return list (rank) The demo cell below shuould display [ ' Mac ' , ' Foster ' , ' Thorny ' , ' Ursula ' , ' Rabbit ' , ' Farva ' ] In [25]: rank = get_ranked_students(grades) rank Out[25]: [ ' Mac ' , ' Foster ' , ' Thorny ' , ' Ursula ' , ' Rabbit ' , ' Farva ' ] In [26]: import nb_1_2_tester tester = nb_1_2_tester . Tester_1_2_7() for i in range ( 5 ): try : tester . run_test(get_ranked_students) (input_vars, original_input_vars, returned_output_vars, true_output_vars) = te except : (input_vars, original_input_vars, returned_output_vars, true_output_vars) = te raise print ( ' Passed. Please submit! ' ) --------------------------------------------------------------------------- 8