Deck 5: Bigger Data: File Io: the While Loop, String Formatting, Reading Online Data in CSV and Json Formats

Question 1

What command is used to open a file named rainfall.txt for reading?

A) r.open("rainfall.txt")
B) rainfall.txt.open();
C) open("rainfall.txt", "w")
D) open("rainfall.txt", "r")

Answer 1

D

Question 2

How is the newline character represented in Python?

A) \n
B) /n
C) "n"
D) NL

Answer 2

A

Question 3

How would you use a for loop to read the text from a file named myFile?

A) for line in myFile:
B) for myFile read line:
C) read line myFile for:
D) for myFile : line

Answer 3

A

Question 4

What statement is used to close a file?

A) exit()
B) stop()
C) close()
D) quit()

Question 5

What string method is used to format values in a string?

A) modulo
B) format
C) close
D) file

Question 6

When using the format method with a string, the ____ character formats a value as an integer.

A) d
B) e
C) f
D) s

Question 7

Case Study 1:
1. >>> item = 'A dozen eggs'
2. >>> itemPrice = 2.4
3. >>> print("{0} costs ${1:.2f}".format(item, itemPrice))
4. ???
5. >>> myDict = {'name':'candy bar', 'price':95}
6. >>> print("The {name} costs {price} cents".format(**myDict))
7. ???
-Refer to the session in the accompanying Case Study 1. What is printed on line 4?

A) A dozen eggs costs $2.4
B) A dozen eggs costs $2.40
C) {0} costs $2.4f
D) The {item} costs {itemPrice} cents

Question 8

Case Study 1:
1. >>> item = 'A dozen eggs'
2. >>> itemPrice = 2.4
3. >>> print("{0} costs ${1:.2f}".format(item, itemPrice))
4. ???
5. >>> myDict = {'name':'candy bar', 'price':95}
6. >>> print("The {name} costs {price} cents".format(**myDict))
7. ???
-Refer to the session in the accompanying Case Study 2. What is printed on line 7?

A) The candy bar costs 95 cents
B) The candy bar costs .95 cents
C) The {name} costs {price} cents
D) The 'name:candy bar' costs 'price:95' cents

Question 9

The ____ method returns the contents of the entire file as a list of strings, where each item in the list represents one line of the file.

A) read
B) readline
C) readall
D) readlines

Question 10

What Python module is used to get online data?

A) Uniform Resource Locator
B) urlliB)request
C) url.request
D) get.url

Question 11

Use the ____ function to connect to an address on the Internet.

A) urlopen()
B) open()
C) request()
D) get()

Question 12

The data embedded in a file that describes the data is called:

A) superdata.
B) titledata.
C) metadata.
D) html.

Question 13

The ____ loop continues to perform the statements in the body of the loop as long as the condition remains true.

A) for
B) while
C) priming
D) infinite

Question 14

If the condition in a while loop never becomes False, (a/an) _____________ loop results.

A) finite
B) infinite
C) complimentary
D) empty

Question 15

Using JSON, data is formatted most like which Python collection?

A) Tuple
B) String
C) List
D) Dictionary

Question 16

Once a file has been opened, it becomes a Python object just like all other data.

Question 17

The string format method is used to create formatted strings in Python.

Question 18

The read(n) method will read and return a string of n characters, or zero characters if n is not provided.

Question 19

It is possible to read online data using Python.

Question 20

You must have more than one for loop in a list comprehension.

Question 21

1. Match each of the descriptions with the appropriate formatting option for strings.
-Put the value in a field 20 characters wide, centered.

A) {0:^20d}
B) {0:>20d}
C) {0:&It;20d}
D) {0:20.2f}

Question 22

1. Match each of the descriptions with the appropriate formatting option for strings.
-Put the value in a field 20 characters wide, right-justified.

A) {0:^20d}
B) {0:>20d}
C) {0:&It;20d}
D) {0:20.2f}

Question 23

1. Match each of the descriptions with the appropriate formatting option for strings.
-Put the value in a field 20 characters wide, left-justified.

A) {0:^20d}
B) {0:>20d}
C) {0:&It;20d}
D) {0:20.2f}

Question 24

1. Match each of the descriptions with the appropriate formatting option for strings.
-Put the value in a field 20 characters wide with two characters to the right of the decimal point.

A) {0:^20d}
B) {0:>20d}
C) {0:&It;20d}
D) {0:20.2f}

Question 25

Describe the functionality of the string format method in Python.

Question 26

Case Study 2:
>>> with open("rainfall.txt", "r") as inFile:
aLine = inFile.readline()
>>> aLine
'Akron 25.81\n'
>>> with open("rainfall.txt", "r") as inFile:
lineList = inFile.readlines()
>>> lineList
['Akron 25.81\n', 'Albia 37.65\n', 'Algona 30.69\n', 'Allison 33.64\n','Alton 27.43\n', 'AmesW 34.07\n', 'AmesSE 33.95\n', 'Anamosa 35.33\n','Ankeny 33.38\n', 'Atlantic 34.77\n', 'Audubon 33.41\n','Beaconsfield 35.27\n', 'Bedford 36.35\n', 'BellePlaine 35.81\n','Bellevue 34.35\n', 'Blockton 36.28\n', 'Bloomfield 38.02\n',
'Boone 36.30\n', 'Brighton 33.59\n', 'Britt 31.54\n', 'Buckeye 33.66\n','BurlingtonKBUR 37.94\n', 'Burlington 36.94\n','Carroll 33.33\n', 'Cascade 33.48\n']
>>> with open("rainfall.txt", "r") as inFile:
fileString = inFile.read()
>>> fileString
'Akron 25.81\nAlbia 37.65\nAlgona 30.69\nAllison 33.64\nAlton
27.43\nAmesW 34.07\nAmesSE 33.95\nAnamosa 35.33\nAnkeny 33.38\n
Atlantic 34.77\nAudubon 33.41\nBeaconsfield 35.27\nBedford 36.35\nBellePlaine 35.81\nBellevue 34.35\nBlockton 36.28\nBloomfield 38.02\nBoone 36.30\nBrighton 33.59\nBritt 31.54\nBuckeye 33.66\nBurlingtonKBUR 37.94\nBurlington 36.94\nCarroll 33.33\nCascade 33.48\n'
>>>
-Refer to the session in the accompanying Case Study 2 and describe the function of the readlines() method.

Question 27

Case Study 2:
>>> with open("rainfall.txt", "r") as inFile:
aLine = inFile.readline()
>>> aLine
'Akron 25.81\n'
>>> with open("rainfall.txt", "r") as inFile:
lineList = inFile.readlines()
>>> lineList
['Akron 25.81\n', 'Albia 37.65\n', 'Algona 30.69\n', 'Allison 33.64\n','Alton 27.43\n', 'AmesW 34.07\n', 'AmesSE 33.95\n', 'Anamosa 35.33\n','Ankeny 33.38\n', 'Atlantic 34.77\n', 'Audubon 33.41\n','Beaconsfield 35.27\n', 'Bedford 36.35\n', 'BellePlaine 35.81\n','Bellevue 34.35\n', 'Blockton 36.28\n', 'Bloomfield 38.02\n',
'Boone 36.30\n', 'Brighton 33.59\n', 'Britt 31.54\n', 'Buckeye 33.66\n','BurlingtonKBUR 37.94\n', 'Burlington 36.94\n','Carroll 33.33\n', 'Cascade 33.48\n']
>>> with open("rainfall.txt", "r") as inFile:
fileString = inFile.read()
>>> fileString
'Akron 25.81\nAlbia 37.65\nAlgona 30.69\nAllison 33.64\nAlton
27.43\nAmesW 34.07\nAmesSE 33.95\nAnamosa 35.33\nAnkeny 33.38\n
Atlantic 34.77\nAudubon 33.41\nBeaconsfield 35.27\nBedford 36.35\nBellePlaine 35.81\nBellevue 34.35\nBlockton 36.28\nBloomfield 38.02\nBoone 36.30\nBrighton 33.59\nBritt 31.54\nBuckeye 33.66\nBurlingtonKBUR 37.94\nBurlington 36.94\nCarroll 33.33\nCascade 33.48\n'
>>>
-Refer to the session in the accompanying Case Study 2 and describe the function of the readline() method.

Question 28

Describe JSON encoding and explain how Python can be used to decode JSON data read from the Internet.

Question 29

Explain the while loop mechanism and provide the syntax, or template, of the structure.

Question 30

What is an infinite loop?

Question 31

Describe the format of a CSV file.

Question 32

What is a list comprehension?

Question 33

Explain how the following session, which creates a list of cubes, could be re-written as a single step using list comprehensions.
>>> cubes = []
>>> for x in range(1, 11):
cubes.append(x * x * x)
>>> cubes
[1, 8, 27, 64, 125, 216, 343, 512, 729, 1000]