Page - 94 - in Programming for Computations – Python - A Gentle Introduction to Numerical Simulations with Python 3.6, Volume Second Edition

94 4 FunctionsandtheWritingofCode i = 7 : 1*8 = i = 8 : 1*9 = i = 9 : 1*10 = i = 10 : 2*1 = i = 11 : 2*2 = ... ... < longer printout... author’s comment > ... i = 97 : 10*8 = i = 98 : 10*9 = i = 99 : 10*10 = Thus, from the 100 values of i, we can uniquely derive the two factors in all the 100products(!),as theprintoutconfirms.With thesequenceof ivalues just shown, however,weget thesystematicorderingof thequestionsused inour2ndversionof theprogram.So, toget thequestions in randomorder,we needsomethingmore. The second observation, is that the function shuffle (Sect.2.4) from numpy can be used to randomize the numbers 0 to 99, and thereby give us a randomized orderingof the products. Now, based on these two observations, we are ready to write down the 3rd version of our program (times_tables_3.py), in which the functionsask_user andpointsare unchangedcomparedto the 2ndversion: import numpy as np def ask_user(a, b): """get answer from user: a*b = ?""" question = ’{:d} * {:d} = ’.format(a, b) answer = int(input(question)) return answer def points(a, b, answer_given): """Check answer. Correct: 1 point, else 0""" true_answer = a*b if answer_given == true_answer: print(’Correct!’) return 1 else: print(’Sorry! Correct answer was: {:d}’.format(true_answer)) return 0 print(’\n*** Welcome to the times tables test! ***\ \n (To stop: ctrl-c)’) N = 10 NN = N*N score = 0 index = list(range(0, NN, 1)) np.random.shuffle(index) # randomize order of integers in index for i in range(0, NN, 1): a = (index[i]//N) + 1 b = index[i]%N + 1 user_answer = ask_user(a, b)