Skills Quiz - Python Edition Solutions

Transcription

1 'XNH8QLYHUVLW\ (GPXQG73UDWW-U6FKRRORI(QJLQHHULQJ EGR 103L Fall 2016 Skills Quiz - Python Edition Solutions Rebecca A. Simmons and & Michael R. Gustafson II Name (please print): NetID (please print): In keeping with the Community Standard, I have neither provided nor received any assistance on this test. I understand if it is later determined that I gave or received assistance, I will be brought before the Undergraduate Conduct Board and, if found responsible for academic dishonesty or academic contempt, fail the class. I also understand that I am not allowed to speak to anyone except the instructor about any aspect of this test until the instructor announces it is allowed. I understand if it is later determined that I did speak to another person about the test before the instructor said it was allowed, I will be brought before the Undergraduate Conduct Board and, if found responsible for academic dishonesty or academic contempt, fail the class. Signature: Notes You will be turning in each problem in a separate pile. Most of these problems will require working on additional pieces of paper - Make sure that you do not put work for more than any one problem on any one piece of paper. For this test, you will be turning in four different sets of work. Again, Please do not work on multiple problems on the same sheet of paper. Also - please do not put work for one problem on the back of another problem. Be sure your name and NetID show up on every page of the test. If you are including work on extra sheets of paper, put your name and NetID on each and be sure to staple them to the appropriate problem. Problems without names will incur at least a 25% penalty for the problem. Work must be down in dark ink and on only one side of the page. This first page should have your name, NetID, and signature on it. It should be stapled on top of and turned in with your submission for Problem I. Every other pile should have your test page on top followed by any previously blank paper used for that problem. You will not need and can not use a calculator on this test. You will be asked to write several lines of code on this test. Make sure what you write is Python code and not mathematics. Be very careful with any symbols you use. You do not need to put the honor code statement in your codes. The honor code statement on this page and your NetID on each problem stands in for that. You may assume that the following have been run for any code you write: import math as m import numpy as np import matplotlib. pyplot as plt If you specifically want to import things in a different way, you need to show that explicitly on each code.

2 Name (please print): Community Standard (print NetID): Problem I: [30 its.] Investigation See CS 101 tests, specifically first problems, for similar code.

3 Name (please print): Community Standard (print NetID): Problem II: [25 its.] Flyin A drone has sensors on board in order to register the drone s location and temperature as it flies. It stores the data set in a rectangular array of text that can be downloaded from the drone and saved as a text file. The data files i called TempData.dat and has six columns of information: the reading number, the time (in seconds), the x and y and z coordinates measured relative to some fixed point on the ground (in meters), and the temperature measured at that time at that location (in Kelvin). The drone takes measurements approximately every two seconds. The start of the data table might resemble: 1.00e e e e e e e e e e e e e e e e e e e e e e e e+02 <etc> but there are potentially more than 4 lines. Write Python code that will perform all the following tasks: (1) Load the data set into an array called temp_data. (2) Copy the reading times into an array called times. (3) Copy the x locations into an array called x. (4) Copy the y locations into an array called y. (5) Copy the z locations into an array called z. (6) Copy the temperatures into an array called temps. (7) Make a plot of the temperatures as a function of time using black squares at each reading. The squares should not be connected to each other. Add a proper title, axis labels, and grid. Save this first plot to a color Encapsulated Postscript file called temp_plot.eps. (8) Make a plot of the distance from the origin as a function of time using red diamonds at each reading. The diamonds should not be connected to each other. Add a proper title, axis labels, and grid. Save this first plot to a color Encapsulated Postscript file called dist_plot.eps. Note that: ρ = x 2 + y 2 + z 2 where ρ is measuring the distance from a point (x,y,z) to the origin. (9) Determine the highest recorded temperature and then report back all the times and locations at which it occurred. You should print the information to the screen using the following as a template: High temp: 2.966e+02 Time: 2.01e+00 Loc: (-2.38e e e-01) Time: 1.42e+01 Loc: (-1.24e e e+00) Time: 1.97e+01 Loc: (-1.92e e e+00) Note that the highest temperature may occur at more than one reading.

4 1 # %% Imports 2 import numpy as np 3 import matplotlib.pyplot as plt 4 5 # %% (1) 6 temp_data = np.loadtxt( ³TempData.dat ³) 7 8 # %% (2) - (6) 9 times = temp_data[:, 1].copy() 10 x = temp_data[:, 2].copy() 11 y = temp_data[:, 3].copy() 12 z = temp_data[:, 4].copy() 13 temps = temp_data[:, 5].copy() # %% (7) 16 plt.figure(1) 17 plt.clf() 18 plt.plot(times, temps, ³ks ³) 19 plt.title( ³Temperature vs. Time ³) 20 plt.xlabel( ³Time, s ³); plt.ylabel( ³Temp, K ³); plt.grid() 21 plt.savefig( ³temp_plot.eps ³) # %% (8) 24 rho = np.sqrt(x**2 + y**2 + z**2) 25 plt.figure(2) 26 plt.clf() 27 plt.plot(times, rho, ³rd ³) 28 plt.title( ³Distance vs. Time ³) 29 plt.xlabel( ³Time, s ³); plt.ylabel( ³Distance, m ³); plt.grid(1) 30 plt.savefig( ³dist_plot.eps ³) # %% (9) 33 max_temp = max(temps) 34 print( ³High temp: {:0.3e} ³.format(max_temp)) 35 # Several ways to do this next part: 36 # Get indices where temps==max_temps - pick one of the following 37 idx_1 = np.where(temps == max_temp)[0] # array -- note [0] is required! 38 idx_2 = [m for m in range(len(temps)) if temps[m] == max_temp] # list # a: loop through locations where temps==max_temp 41 for k in idx_1: # or idx_2 42 print( ³Time: {:0.2e} Loc: ({:+0.2e} {:+0.2e} {:+0.2e}) ³.format( 43 times[k], x[k], y[k], z[k])) # b: find how often temps==max_temp and loop that many times 46 for k in range(len(idx_1)): # or idx_2 47 print( ³Time: {:0.2e} Loc: ({:+0.2e} {:+0.2e} {:+0.2e}) ³.format( 48 times[idx_1[k]], x[idx_1[k]], y[idx_1[k]], z[idx_1[k]])) # c: slice values corresponding to where temps==max_temp and 51 # loop through those 52 times_max = times[idx_1] # in all cases, or idx_2 53 x_max = x[idx_1] 54 y_max = y[idx_1] 55 z_max = z[idx_1] for k in range(len(times_max)): 58 print( ³Time: {:0.2e} Loc: ({:+0.2e} {:+0.2e} {:+0.2e}) ³.format( 59 times_max[k], x_max[k], y_max[k], z_max[k]))

5 Name (please print): Community Standard (print NetID): Problem III: [25 its.] Functions (1) Write a function called just_add_red.m that takes a string as an input - the string will be a paint color. The returned variable will contain a string that indicates what color paint you get if you combine that paint with red paint. You will only be required to have your function identify the following combinations: Input Output blue purple yellow orange For any other inputs, your program should print Unknown color! and return None. You may assume the user has given you an all-lowercase string as an input. Here are some sample runs: In [1]: just_add_red(³blue ³) Out[2]: ³purple ³ In [2]: just_add_red(³green ³) Unknown color! (2) Write a function called bump that takes two arguments - a period T and a list of locations x - and returns the following expression for a single T value and a list of x values: 0 x < T/4 bump(t,x) = cos ( 2π T x) T/4 x T/4 0 x > T/4 (3) Write a function file called int_times that will take two inputs and returns an output. Your program needs to make sure that each input is a single integer value (no lists, tuples, or strings). If the rules are broken, your function should print an appropriate complaint and return None. Otherwise, the output should merely be the product of your two inputs. Here are some example runs: In [1]: int_times(1.2, 3.4) Function requires two single integer inputs! In [2]: int_times([1, 2], 3) Function requires two single integer inputs! In [3]: int_times(3, 4.5) Function requires two single integer inputs! In [4]: int_times(3.4, 5) Function requires two single integer inputs! In [5]: int_times(4, 5) Out[5]: 20

6 1 def just_add_red(orig): 2 if orig == ³blue ³: 3 return ³purple ³ 4 elif orig == ³yellow ³: 5 return ³orange ³ 6 else: 7 print( ³Unknown color! ³) 8 return None 1 # %% Imports 2 import math as m 3 import numpy as np 4 import matplotlib.pyplot as plt 5 6 def bump(t, x): # using a loop; appending values each time 7 out = [] 8 for k in range(len(x)): 9 if (-T / 4) <= x[k] <= T / 4: 10 out += [m.cos(2 * m.pi * x[k] / T)] 11 else: 12 out += [0] 13 return out def bump2(t, x): # using logical masks 16 xa = np.array(x) 17 return ((-T / 4 <= xa) & (xa <= T / 4)) * np.cos(2 * m.pi * xa / T) def bump3(t, x): # list comprehensions; initial list of 0s 20 out = [0] * len(x) 21 for k in [m for m in range(len(x)) if -T / 4 < x[m] < T / 4]: 22 out[k] = m.cos(2 * m.pi * x[k] / T) 23 return out if name == ³ main ³: 26 # %% shows usage; not part of test 27 t = np.linspace(-1, 1, 100) 28 plt.figure(1) 29 plt.clf() 30 plt.plot(t, bump(1, t), ³k-³) 1 def int_times(val_1, val_2): 2 # Check number of arguments first, then sizes, then if integers 3 if not isinstance(val_1, int) or not isinstance(val_2, int): 4 print( ³Function requires two single integer inputs! ³) 5 return None 6 else: 7 return val_1 * val_2

7 Name (please print): Community Standard (print NetID): Problem IV: [20 its.] Loops (1) Determine the values of A, B, and C at the end of the following code: B = [0] C = 0; for A in range(1,6,2): B += [A] C += A (2) Write a script called stay_odd.m which asks the user for odd integers. The script should store the odd values in a list called keepers and keep running until the users inputs a number that is not an odd integer. You may assume that the user only enters single integers. After the user inputs the non-odd value, your script should report how many numbers were entered and how many of them were positive. Here is an example run: Odd number: 1 Odd number: 5 Odd number: -3 Odd number: -9 Odd number: 21 Odd number: 6 5 odd value(s) 3 positive odd value(s) In [2]: print(keepers) [1, 5, -3, -9, 21]

8 In [1]: A Out[1]: 5 In [2]: B Out[2]: [0, 1, 3, 5] In [3]: C Out[3]: 9 1 # %% Get first value 2 x = int(input( ³Odd number: ³)) 3 count = 0 4 pos_count = 0 5 keepers = [] 6 7 # %% Run loop as long as entries are odd 8 while x % 2 == 1: 9 # if you are here, store, addto the count; check if it is positive 10 keepers += [x] 11 count += 1 12 if x > 0: 13 pos_count += 1 14 # get the next value 15 x = int(input( ³Odd number: ³)) # %% Print information 18 print( ³{:d} odd value(s) ³.format(count)) 19 print( ³{:d} positive odd value(s) ³.format(pos_count)) # could delete count and use: 22 # len(keepers) 23 # in first print statement #could delete pos_count and use: 26 # len([m for m in keepers if m>0]) 27 # in second print statement