Description
- Arithmetic, Strings, Lists, Loops, and Formatting (100 points)
- Create a new, empty Python code file named hw1.1.py.You may use IDLE, Spyder, or some other Python Integrated Development Environment (IDE). In the lecture, we saw how to compute a Fahrenheit-to-Celsius temperature conversion, and how to display output like:
80 degrees Fahrenheit is 26.666666666666668 Celsius
Add code in hw1.1.py to perform this computation and display the same kind of
output for Fahrenheit temperatures 0, 32, 45, 60, 70, 95, and 212. (Remember
that when you make changes to a Python code file in IDLE, you must save the
file first [which you can do in Windows by pressing Ctrl-S] before you can run
the modified program [which you can do in Windows by pressing F5].)
- Add code to hw1.1.py to perform Celsius-to-Fahrenheit temperature conversion, and display output for Celsius temperatures 0, 10, 15, 20, 25, 30, and 100.
- Here is a table of predicted high temperature (Fahrenheit), low temperature, and percent humidity in Pittsburgh for 15 days, starting on Aug. 30, 2018:
Date Hi(F) Lo(F) %Hum
AUG 30 79 64 60
AUG 31 82 66 20
SEP 1 85 68 20
SEP 2 85 68 30
SEP 3 87 69 30
SEP 4 87 69 20
SEP 5 87 69 20
SEP 6 85 67 20
SEP 7 81 63 30
SEP 8 79 61 20
SEP 9 77 61 20
SEP 10 77 59 20
SEP 11 77 59 20
SEP 12 77 59 20
SEP 13 77 59 50
You can copy-and-paste this table into your hw1.1.py file. Since this table is not valid Python code, you can “comment it out” by enclosing the entire table within triple quotes:
“””
Date Hi(F) Lo(F) %Hum
…
SEP 13 77 59 50
“””
After you have copied-and-pasted the table and “commented it out” by using the
triple quotes, save and run your program to make sure the commented-out table
does not cause an error.
- Define a list named dt containing the dates as strings (str):
dt = [‘AUG 30’, …, ‘SEP 13’]
(At this point, we are not going to try to create dt directly out of the triple-quoted
string containing the table. Just define dt manually, as illustrated above.)
Define a list named hi containing the high temperatures, a list named lo
containing the low temperatures, and a list named hm containing the humidities.
Then, use a for loop to display a copy of the table to the user’s screen, like this:
print(‘Date Hi(F) Lo(F) %Hum’)
num_days = len(dt)
for i in range(num_days):
print(dt[i], hi[i], lo[i], hm[i])
Save and test. Does the displayed table look exactly like the original table?
- You can add spaces between fields of output in a print() function call by displaying strings of spaces! For example, change the print() function call to:
print(dt[i], ‘ ‘, hi[i], lo[i], hm[i])
You will see that this adds three spaces between the end of dt[i] and the beginning of hi[i]. (Why three spaces? Because the string contains two spaces, and the comma after the string causes another space to be displayed.)
Revise your print() function call so that the displayed columns line up exactly as in the original table. Save and test.
- You can compute the sum of the values in a list of numbers using a loop, like this:
m = [1, 2, 3, 5]
tot = 0
for val in m:
tot += val
print(‘Sum of values in’, m, ‘is’, tot)
Output:
Sum of values in [1, 2, 3, 5] is 11
Or, you can use Python’s built-in sum() function:
m = [1, 2, 3, 5]
tot = sum(m)
print(‘Sum of values in’, m, ‘is’, tot)
Output:
Sum of values in [1, 2, 3, 5] is 11
After the display of the table, add code to compute and display the mean, median, and sample standard deviation of high temperatures, low temperatures, and humidities for the 15 dates in the table. Hint: How can you put the values of a list in ascending order, so that the middle value is the median? You will not want to do this on the original lists of temperatures or humidities: make a copy of a list, and then modify the copy:
hi_copy = hi.copy()
Now you can safely modify hi_copy without modifying hi.
Recall that the sample standard deviation for N observations of some value xi is:
- In part (e), making your displayed table look like the original table by using strings of spaces between the data, high temp, low temp, and humidity really works because of luck: the temperature and humidity values were all 2 digits wide. What if some were 3 digits wide and some were just 1 digit wide? Consider these (made up) 15 days in Death Valley, California:
Date Hi(F) Lo(F) %Hum
AUG 30 1077815
AUG 31 10980 8
SEP 1 1047912
SEP 2 1017813
SEP 3 9977 9
SEP 4 9878 8
SEP 5 9578 8
SEP 6 987810
SEP 7 987710
SEP 8 1028010
SEP 9 1048112
SEP 10 10180 8
SEP 11 997815
SEP 12 967715
SEP 13 997812
Now we will need a more precise way of formatting.
Python 3.7 provides several generations of string formatting facilities. Here we will work with the str type’s format() method, which allows us to control field widths, left-, center-, and right-justification, digits of precision displayed for floating-point numbers, and so forth.
Read the very nice introduction to the format() method at:
https://www.digitalocean.com/community/tutorials/how-to-use-string-formatters-in-python-3
and try the examples given there. If we had our Death Valley table’s columns stored in lists dt2, hi2, lo2, and hm2, we could reproduce the table using format() as follows:
print(‘{:<6s}{:>7s}{:>7s}{:>6s}’.format(
‘Date’, ‘Hi(F)’, ‘Lo(F)’, ‘%Hum’))
num_days = len(dt2)
for i in range(num_days):
print(‘{:<6s}{:>7d}{:>7d}{:>6d}’.format(
dt2[i], hi2[i], lo2[i], hm2[i]))
Create the lists dt2, hi2, lo2, and hm2 from the Death Valley data, and confirm
that the above code works for accurately reproducing the table.
- Now, use the Fahrenheit-to-Celsius conversion formula to produce the table in Celsius rather than Fahrenheit. Display 2 digits after the decimal point in the Celcius temperatures. For example,
print(‘[{:>7.2f}]’.format(26.666666666666668))
will display:
[ 26.67]
You will need to widen the field widths for the second and third columns. The first couple of lines of the Celsius table should look like:
Date Hi(C) Lo(C) %Hum
AUG 30 41.6725.56 15
- In the Python 3.7 documentation:
https://docs.python.org/3.7/library/string.html#formatstrings
read section Format Specification Mini-Language and try out the examples in theFormat Examples section that follows. (You do not need to include these Format Examples in your homework code file.)
- You can use nestedfor loops, that is, one for loop within another, like this:
for var1 in iterable1:
for var2 in iterable2:
stmt
…
Create a nicely formatted table with 20 rows of 5 columns, where the rows are for the integer values 0 through 19, and the columns are the cube root, square root, integer value, square, and cube of each integer values. Not all of the cube roots or square roots will be integers, of course, so display all of these as floating point values with a precision of 6 digits after the decimal place. Arrange for all five columns to be of equal width.
REMEMBER to put all authors’ names into your source code file.Upload your hw1.1.py file to Canvas for this assignment.
