Session 3 - Part 1

Question 1

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How can you convert a string to uppercase in Python?

Answer 1

You can utilize the upper() method.

Question 2

How can you convert a given string to lowercase in Python?

Answer 2

You can utilize the lower() method.

Question 3

How can you convert a given string to title case in Python?

Answer 3

You can utilize the title() method.

Question 4

How can you remove leading and trailing whitespace characters from a string in Python?

Answer 4

You can achieve this by using the strip() method.

Question 5

What is the output of this code?

my_string = ‘ the cat Sat on The Mat. ‘

print(my_string.upper())

Answer 5

(spaces before) THE CAT SAT ON THE MAT.

Question 6

What is the output of this code?

my_string = ‘ the cat Sat on The Mat. ‘

print(my_string.lower())

Answer 6

(spaces before) the cat sat on the mat.

Question 7

What is the output of this code?

my_string = ‘ the cat Sat on The Mat. ‘

print(my_string.title())

Answer 7

(spaces before) The Cat Sat On The Mat

Question 8

What is the output of this code?

my_string = ‘ the cat Sat on The Mat. ‘

print(my_string.strip())

Answer 8

the cat Sat on The Mat.

Question 9

What is the output of this code?

my_string = ‘ the cat Sat on The Mat. ‘

print(my_string.strip().lower())

Answer 9

the cat sat on the mat.

Question 10

Explain the following Python code:

my_string = ‘ the cat Sat on The Mat. ‘

print(my_string.upper()) - (3)

Answer 10

This code defines a string variable my_string containing the text “the cat Sat on The Mat.” with leading and trailing whitespace characters.

The upper() string method is then applied to my_string, converting all characters in the string to uppercase.

Finally, the result, which is the string in uppercase, is printed to the output console.

Question 11

Explain the following Python code - (2)

my_string = ‘ the cat Sat on The Mat. ‘

print(my_string.title())

Answer 11

This code takes the string stored in the variable my_string and prints it out in title case.

In title case, the first character of each word is capitalized, and the rest of the characters are in lowercase.

Question 12

Explain the following Python code - (2)

my_string = ‘ the cat Sat on The Mat. ‘

print(my_string.strip())

Answer 12

This code removes leading and trailing whitespace characters (such as spaces, tabs, and newline characters) from the string stored in the variable my_string.

The strip() method is used to perform this operation, and the resulting string with whitespace removed is printed to the console.

Question 13

You can combine these string methods (upper, lower, title, strip) like this:

Answer 13

my_string.strip().lower()

Question 14

Explain the following Python code and how it combines string methods - (4)

my_string = ‘ the cat Sat on The Mat. ‘

print(my_string.strip().lower())

Answer 14

This code demonstrates the combination of string methods in Python.

First, the strip() method is applied to my_string to remove leading and trailing whitespace characters.

Then, the lower() method is applied to the resulting string, converting all characters to lowercase.

The combined effect of these methods is that the string is stripped of whitespace and converted to lowercase before being printed to the console.

Question 15

Explain the meaning of the following string assignment (i.e., (i.e., “string assignment” refers to the process of assigning a string value to a variable) - (3)

my_string=”\n hello world \t”

Answer 15

In the given string assignment, my_string, the escape sequences \n and \t are used.

\n represents a newline character, causing the text “hello world” to start on a new line.

\t represents a tab character, adding tab spaces (equivalent to multiple spaces) before the text “hello world”.

Question 16

Exercise
Change the following code so that it prints the string ‘All In Title Case’ and without the leading and trailing spaces.

Bonus points. Use an f-string to center the modified string in some asterisks like this ** Hello World! **

Code:

my_string=”\n hello world \t”
print(my_string)

Answer 16

my_string=”\n hello world \t”
print(f”{my_string.title().strip()}”)

Output:
* Hello World*

Question 17

What are string member functions in Python - (3)

Answer 17

String member functions” refer to methods that are specific to strings and are accessed using dot notation.

These methods include functions to change the case of strings (e.g., lower(), upper(), title(), strip(), join strings (join()), split strings (split()), and others.

They are essential for string manipulation tasks in Python

Question 18

Describe the importance of string member functions in Python - (2)

Answer 18

String member functions are essential for cleaning up and altering the case of strings.

This is not only useful for printing and other output purposes but also in cases where we need to compare strings ‘case-insensitively’ (in other words without caring whether something is upper- or lower-case).

Question 19

Let’s imagine we have a password system for school district

Each time someone wants to get in they have to type the password (‘pencil’). But, to make things easier, we don’t want it to fail if they have the CAPS LOCK key on, or if they are German And Need To Capitalize Lots Of Words. Or if they have accidentally added a space or tab at the start of the string (YNiC screensaver unlock box - I’m looking at you!).

How might we do this? - Two ways - (2)

Answer 19

Using if statements

Turning any user input to lower case and check against ‘pencil’

Question 20

Let’s imagine we have a password system for school district

Each time someone wants to get in they have to type the password (‘pencil’). But, to make things easier, we don’t want it to fail if they have the CAPS LOCK key on, or if they are German And Need To Capitalize Lots Of Words. Or if they have accidentally added a space or tab at the start of the string (YNiC screensaver unlock box - I’m looking at you!).

First way if statements:

Answer 20

if (inputWord==’pencil’) or (inputWord==’PENCIL’) or (inputWord==’Pencil’) or (inputWord=…..

Question 21

Why might using a series of if statements to check for variations in capitalization or leading whitespace be considered clunky? - (2)

e.g.,

if (inputWord==’pencil’) or (inputWord==’PENCIL’) or (inputWord==’Pencil’) or (inputWord=…..

Answer 21

Using a series of if statements to check for variations in capitalization or leading whitespace can be considered clunky because it requires writing repetitive code and becomes cumbersome to maintain, especially if the password changes.

Also you may not think of all the variations people can type pencil

Question 22

Let’s imagine we have a password system for school district

Each time someone wants to get in they have to type the password (‘pencil’). But, to make things easier, we don’t want it to fail if they have the CAPS LOCK key on, or if they are German And Need To Capitalize Lots Of Words. Or if they have accidentally added a space or tab at the start of the string (YNiC screensaver unlock box - I’m looking at you!).

Second way -Turning any user input to lower case and check against ‘pencil’ - produce this code - target string is ‘pencil’

Answer 22

target_string = ‘pencil’

user_input = input(‘Login with user password: ‘)

user_input = user_input.lower()

if user_input == target_string:
print(“Welcome to the Seattle Public School District DATANET”)
else:
print(“Password denied”)

Question 23

What is the following outputs given these inputs? - (5)

code:

target_string = ‘pencil’

user_input = input(‘Login with user password: ‘)

user_input = user_input.lower() # We could also ‘strip’ it to remove whitespace

if user_input == target_string:
print(“Welcome to the Seattle Public School District DATANET”)
else:
print(“Password denied”)

	inputs:
	pencil
	PENCIL
	PeNCIL
	pen

Answer 23

Login with user password: pencil Welcome to the Seattle Public School District DATANET

Login with user password: Pencil Welcome to the Seattle Public School District DATANET

Login with user password: pencil Welcome to the Seattle Public School District DATANET

Login with user password: PeNCIL Welcome to the Seattle Public School District DATANET

Login with user password: pen Password denied

Question 23

What is the advantage of converting the input to lowercase before comparing it to the password?

e.g.,

target_string = ‘pencil’

user_input = input(‘Login with user password: ‘)

user_input = user_input.lower()

Answer 23

Converting the input to lowercase before comparison ensures case insensitivity, simplifying code and making it more robust by ignoring variations in capitalization or leading whitespace.

Question 24

Explain the following Python code - (6)

target_string = ‘pencil’

user_input = input(‘Login with user password: ‘)

user_input = user_input.lower()

if user_input == target_string:
print(“Welcome to the Seattle Public School District DATANET”)
else:
print(“Password denied”)

Answer 24

This code prompts the user to enter a password and compares it with a target password stored in lower case.

Firstly, the target password ‘pencil’ is stored as all lower-case characters in variable ‘target_string’

Then, the user is prompted to input their password.

The user_input.lower() function converts the user’s input to lower case, ensuring that the comparison is not case-sensitive.

If the user’s input matches the target password, ‘Welcome to the Seattle Public School District DATANET’ is printed; otherwise, ‘Password denied’ is printed.

This approach ensures that the password comparison ignores variations in capitalization and provides a robust password validation mechanism.

Question 25

What is the output of this code?

target_string = ‘pencil’

user_input input(‘Login with user password’

Answer 25

Question 26

might you use a while loop to keep going until someone gets the password right? BONUS POINTS: Why might this be a bad idea?

Answer 26

We will just keep trying lots of passwords

Question 27

Quick Exercise
Modify the code from the example above so that it does the comparison in upper case.

target_string = ‘pencil’

user_input = input(‘Login with user password: ‘)

user_input = user_input.lower() # We could also ‘strip’ it to remove whitespace

if user_input == target_string:
print(“Welcome to the Seattle Public School District DATANET”)
else:
print(“Password denied”)

Answer 27

tgt_string = ‘PENCIL’

user_input = input(‘Enter a string: ‘)

user_input = user_input.upper()

if user_input == tgt_string:
print(“Welcome to the Seattle Public School District DATANET”)
else:
print(“Password denied”)

Question 28

Explain the functionality of the split string member function .spilt() in Python.

Answer 28

The split string member function is designed to take a string and split it into a list of strings

Question 29

What is the default behaviour of .spilt() string member function?

Answer 29

By default, it splits the string on any whitespace characters (such as spaces, tabs, or newlines/carriage-return characters),

Question 30

Explain the functionality of the provided Python code - (10)

dat = ‘The cat sat on the mat’

res = dat.split()

print(type(res))

print(res)

print(len(res))

Answer 30

The provided code utilizes the split() method to split the string “The cat sat on the mat” into individual words.

It initializes a string variable dat with the value ‘The cat sat on the mat’.

The split() method is applied to dat, splitting the string into individual words based on whitespace characters.

The resulting list is stored in the variable res.

It prints the type of res (which confirms it’s a list), the contents of res (the individual words), and the length of res (the number of words in the original string).

Output:

<class ‘list’>
[‘The’, ‘cat’, ‘sat’, ‘on’, ‘the’, ‘mat’]
6

You can see that it takes the string “The cat sat on the mat” and breaks it apart into 6 strings - one for each part of the string between each space character.

The length of the resulting list is 6, corresponding to the number of words in the original string.

Question 31

Explain how to change the character on which the split method splits a string in Python,

Answer 31

To change the character on which the split method splits a string, you can pass a desired ‘separator’ character as an argument to the method.

Question 32

Example of change the character on which spilt spilts the string by passing our desired ‘seprator; character as an arguement - (2)

if we have a string which is separated by commas:

dat = ‘Person,Condition,RT’
res = dat.split(‘,’)
print(res)

Explain:

Answer 32

In this example, the string dat is split into individual parts at each comma character, and the resulting list is printed:

Output:
[‘Person’, ‘Condition’, ‘RT’]

Question 33

Why is this formulation particularly useful e.g., spilting string based on comma character ‘,’:

dat = ‘Person,Condition,RT’

res = dat.split(‘,’)

print(res)

Answer 33

This formulation is particularly useful because a common way to store data in scientific studies is as a Comma-Separated Values file (often known as a CSV file).

Question 34

Modify this code below to spilt on a different character like ‘o’:

dat = ‘Person,Condition,RT’

res = dat.split(‘,’)

print(res)

Answer 34

dat = ‘Person,Condition,RT’

res = dat.split(‘o’)

print(res)

Question 35

What is output of this code:
dat = ‘Person,Condition,RT’

res = dat.split(‘o’)

print(res)

Answer 35

[‘Pers’, ‘n,C’, ‘nditi’, ‘n,RT’]

Question 36

Explain this code - (5)

dat = ‘Person,Condition,RT’

res = dat.split(‘o’)

print(res)

Answer 36

The string ‘Person,Condition,RT’ is stored in the variable dat.

The split(‘o’) method is applied to dat, splitting the string at each occurrence of the letter ‘o’.

The resulting list is stored in the variable res.

It prints the content of res, which contains the parts of the string split at each occurrence of ‘o’.

So output would be: [‘Pers’, ‘n,C’, ‘nditi’, ‘n,RT’]

Question 37

Explain the concept of “white-space” in Python and what it refers to - (2)

Answer 37

In Python, “white-space” refers to characters such as tabs, spaces, and newline/carriage-return characters.

These characters are used to format code or data files and are typically invisible when displayed.

Question 38

What does “carriage return” mean in the context of datafiles? - (2)

Answer 38

n data files, “carriage return” indicates the end of a line in a datafile.

In Python, it is represented by the special symbol \n, which is interpreted as a “newline” character.

Question 39

Example of using \n

What i the output of this code?

print(“Hello\nWorld”)

Answer 39

Hello
World

Question 40

Explain this code and its output - (3)

print(“Hello\nWorld”)

Answer 40

The string “Hello\nWorld” is passed to the print() function.

You have inserted a newline in between the two words, so they get printed on different lines such as:

Output
Hello
World

Question 41

What is a tab character in Python? - (2)

Answer 41

A tab character in Python, represented as \t, is a special type of whitespace character used to align text by moving the cursor to the next tab stop at a fixed interval.

It is commonly used for indentation and formatting purposes in documents, code, or data files.

Question 42

Explain useage of \t in this Python code:

print(“Name:\tJohn Doe”)
print(“Age:\t25”)
print(“City:\tNew York”)

Answer 42

When executed, this code will print information about a person with each attribute (name, age, city) followed by a tab character (\t) to align the text neatly in columns.

Question 43

What is output of this code?

print(“Name:\tJohn Doe”)
print(“Age:\t25”)
print(“City:\tNew York”)

Answer 43

Name: John Doe
Age: 25
City: New York

Question 44

Explain the functionality of the provided Python code: print(“This\tis\tindented”). - (2)

Answer 44

Specifically, it prints the string “This”, followed by a tab character (\t), then “is”, another tab character, and finally “indented”.

When executed, the output will display “This”, followed by several spaces, then “is”, followed by several spaces, and finally “indented”.

Question 45

What is output of code going to be?

print(“This\tis\tindented”)

Answer 45

This is indented

Question 46

Explain the functionality of the provided Python code - (6)

my_string = ‘Country\t,GDP\t,Happiness\t,Authoritarianism\t\n\r’
string_list = my_string.split(“,”)

for thisString in string_list:
cleanString = thisString.strip()
print(cleanString)

Answer 46

This code initializes a string my_string containing tab-separated values (with commas as delimiters) and newline/carriage return characters.

The string is then split into a list of strings using the split() method with a comma delimiter.

Each element in the resulting list retains the tab characters (\t).

The for loop iterates over each element in string_list, and the strip() method is applied to remove any leading or trailing whitespace, including the tab characters, from each element.

Finally, it prints each cleaned string:

Country
GDP
Happiness
Authoritarianism

Question 47

What is output of this code?

my_string = ‘Country\t,GDP\t,Happiness\t,Authoritarianism\t\n\r’
string_list = my_string.split(“,”)

for thisString in string_list:
cleanString = thisString.strip()
print(cleanString)

Answer 47

Country
GDP
Happiness
Authoritarianism

Question 48

Explain the functionality of the provided Python code - (5)

my_string = ‘Country\t,GDP\t,Happiness\t,Authoritarianism\t\n\r’
string_list = my_string.split(“,”)
print(string_list)

Answer 48

This code initializes a string my_string containing tab-separated values (with commas as delimiters) and newline/carriage return characters.

Then, it splits the string into a list of strings using the split() method with a comma delimiter

However, the \t and \n\r characters are retained within the string elements in the list, rather than being interpreted as tabs and newline/carriage returns. .

Finally, it prints the resulting list.

Output: [‘Country\t’, ‘GDP\t’, ‘Happiness\t’, ‘Authoritarianism\t\n\r’]

Question 49

A full pathname for a file on a computer consists of a.. together these elements uniquelty identifiy - (2)

Answer 49

directory (or folder) and a filename, which must be unique within the directory.

Together, these elements uniquely identify the location of the file within the file system.

Question 50

For example, on a Linux system, the full path to a file in a user’s home directory might be:

Answer 50

/home/alex/Documents/PiN_Handout.pdf

Question 51

/home/alex/Documents/PiN_Handout.pdf

The directory which is the file… and filename within directory is… - (2)

Answer 51

In this case, the directory which the file is in is /home/alex/Documents and the filename within the directory is PiN_Handout.pdf.

each of home, alex and Documents is a directory. alex is nested within home and Documents is nested within alex.

Question 52

top level directory on Linux systems is known as / -

Answer 52

top of the tree /root of file system

Question 53

Explain the concepts of absolute and relative paths in computing

Answer 53

An absolute path provides the complete address of a file or directory starting from the root directory, whereas a relative path specifies the location of a file relative to the current working directory.

Question 54

Provide an example of an absolute path in computing - (2)

Answer 54

An example of an absolute path in computing is

/home/user/documents/my_file.txt.

This path specifies the complete address of the file my_file.txt, starting from the root directory (/) and including all intermediate directories (home, user, documents).

Question 55

Give an example of a relative path in computing - (3)

Answer 55

An example of a relative path in computing is data/my_data.csv.

This path specifies the location of the file my_data.csv relative to the current working directory.

It indicates that the file is located within a directory named data within the current working directory.

Question 56

If a filename does not have a full directory component (i.e. it does not start with / or C: on Windows), it is said to be

Answer 56

relative.

Question 57

Why is understanding absolute and relative paths important? - (2)

Answer 57

so that you understand where your program will look for files (when you are reading data in) and write files out (when you save data, figures etc out).

Understanding absolute and relative paths is important for determining where files will be located or saved when working with programs.

Question 58

Example of relative path

my_filename = ‘my_file.txt’

If we use this filename when opening or saving a file, it wil be - (2)

Answer 58

the file will be searched for or placed in the current working directory

This is the directory which the script “thinks” that it is inside of.

Question 59

What does the %pwd command do in Colab and how is it useful? - (3)

Answer 59

The %pwd command in Colab prints the current working directory on the command line interface.

It is a magic command that displays the directory location within the file system where the script or notebook is currently executing.

This information is useful for understanding the file system context and specifying file paths in the script or notebook.

Question 60

Explain the behavior of a Python script in relation to determining its current directory during execution as compared to Colab -(3)

Answer 60

When running a Python program, it may need to determine its current directory during execution.

This directory can change independently of the current directory of the Colab interpreter.

The Python script has the ability to manipulate its own execution environment, including changing directories, without affecting the directory of the Colab interpreter

Question 61

Explain the rationale behind using os.getcwd() in Python scripts. than %cwd? - (2)

Answer 61

os.getcwd() is preferred in Python scripts for retrieving the current working directory due to its portability and consistency across different environments.

Unlike %cwd, which is specific to Colab and may not work in other environments, os.getcwd() is a standard Python library function that works reliably across various platforms

Question 62

What function can you use within a Python script to find the current working directory? - (2)

Answer 62

Within a Python script, you can use the os.getcwd() function to find the current working directory.

This function returns a string representing the current directory path.

Question 63

How can you change the current working directory within a Python script? - (2)

Answer 63

You can change the current working directory within a Python script using the os.chdir(dirname) function, where dirname is a string containing the directory path to which you wish to change.

Question 64

Before using os.getcwd() or os.chdir(dirname) and os.listdir(), we have to import module called

Answer 64

os

Question 65

What does module os provide?

Answer 65

provides functions for interacting with the operating system.

Question 66

Explain this code:

import os

print(os.getcwd()) - (3)

Answer 66

The code snippet imports the os module in Python, which provides functions for interacting with the operating system.

It then uses the os.getcwd() function to retrieve the current working directory.

The output of os.getcwd() will be the current directory in which the Python script is being executed.

Question 67

Explain the functionality of os.listdir().

Answer 67

os.listdir() is a function in Python’s os module that returns contents , by default, of the current working directory

Question 68

Explain the purpose of the provided code snippet. - (3)

import os
os.chdir(‘/content/sample_data’)
print(os.listdir())
print(os.getcwd())

Answer 68

The code snippet changes the current working directory to /content/sample_data using the os.chdir() function, specifying an absolute path (‘it starts with a / meaning the ‘root’ of the tree’)

Then, it prints the contents of the directory using os.listdir(), which lists all the files and directories within the specified directory.

Finally, it prints the current working directory using os.getcwd(), which returns the path of the current working directory.

Question 69

It is usually best to avoid changing the directory that your program is working in and use

Answer 69

absolute paths instead

Question 70

Why is it good to use abolsute file path names?

Answer 70

One reason is that if your programme crashes while you are in a different directory you might not be in the place you expect when you restart it.

Question 71

If, when you are reading data, you are getting errors such as “No such file or directory”, it is probably because you are using a - (2)

Answer 71

relative file path and are not in the correct directory.

Or you have just typed the filename wrong.

Question 72

What is the function used for joining parts of a file path together?

Answer 72

The function used for joining parts of a file path together is os.path.join.

Question 73

Why is joining parts of a file together using os.path.join() useful?

Answer 73

This is particularly useful if we want to open many files from the same directory

Question 74

In os.path.join () we can simply

Answer 74

pass it as many components of the path as we have, and it will join them in the correct manner.

Question 75

Explain what does code does - (4)

from os.path import join

my_dir = ‘/content/sample_data/’

my_file = ‘mnist_test.csv’

my_filename = join(my_dir, my_file)

print(my_filename)

Answer 75

The code snippet demonstrates the usage of the join function from the os.path module which joins together directory and file names, creating full file paths (with separators appropriate to the file system you are on).

then defines a directory path (my_dir) and a file name (my_file).

Using os.path.join, it joins the directory path and file name to create a full file path to store in variable (my_filename).

It then prints my_filename which will be: /content/sample_data/mnist_test.csv

Question 76

os.path.join() can also take a

Answer 76

string instead of a variable

Question 77

What does the provided code snippet do? - (2)

my_filename2 = join(my_dir, ‘california_housing_test.csv’)

print(my_filename2)

Answer 77

The code snippet combines a directory path (my_dir) with a filename (‘california_housing_test.csv’) to create a full file path (my_filename2).

The resulting file path is then printed.

Question 78

What is the output of this code?

my_filename2 = join(my_dir, ‘california_housing_test.csv’)

print(my_filename2)

Answer 78

/content/sample_data/california_housing_test.csv

Question 79

You can also pass multiple individual dictionaries to to the join function e.g,

Answer 79

print(join(‘/home’,my_dir, ‘ynic’, ‘presentations’, ‘teaching’, ‘pin’,’file.txt’))

Question 80

What does this code do? - (3)

from os.path import join

my_dir = ‘alex’

print(join(‘/home’,my_dir, ‘ynic’, ‘presentations’, ‘teaching’, ‘pin’,’file.txt’))

Answer 80

The code snippet showcases the usage of the join function from the os.path module to create a full directory path by joining together multiple individual directory names.

Starting from the root directory /home, it sequentially adds each directory name (‘alex’, ‘ynic’, ‘presentations’, ‘teaching’, ‘pin’) along with the filename ‘file.txt’.

The resulting full directory path is then printe

Question 81

What is output of this code?

from os.path import join

my_dir = ‘alex’

print(join(‘/home’,my_dir, ‘ynic’, ‘presentations’, ‘teaching’, ‘pin’,’file.txt’))

Answer 81

/home/alex/ynic/presentations/teaching/pin/file.txt

Question 82

Write a script which creates and prints out filenames for the output files S01.txt to S10.txt in the directory /home/pin/my_data. Obviously these files do not really exist, but you can still create variables containing these paths. You will need to review loops, string formatting and path joining.

Answer 82

from os.path import join
base_path=’/home/pin/my_data/’

nSubjects=10 # Because what if we collect more subjects? All we have to do is change this

b=10
a=f’My favourite number is {b} ‘
print(a)

for thisSub in range(1,nSubjects+1): # The +1 is to make sure we go from 1 to 10 inclusive
fileName = f”S{thisSub:02}.txt”

print(join(base_path,fileName))

Question 83

What is the output of this code?

from os.path import join
base_path=’/home/pin/my_data/’

nSubjects=10 # Because what if we collect more subjects? All we have to do is change this

b=10
a=f’My favourite number is {b} ‘
print(a)

for thisSub in range(1,nSubjects+1): # The +1 is to make sure we go from 1 to 10 inclusive
fileName = f”S{thisSub:02}.txt”

print(join(base_path,fileName))

Answer 83

/home/pin/my_data/S01.txt
/home/pin/my_data/S02.txt
/home/pin/my_data/S03.txt
/home/pin/my_data/S04.txt
/home/pin/my_data/S05.txt
/home/pin/my_data/S06.txt
/home/pin/my_data/S07.txt
/home/pin/my_data/S08.txt
/home/pin/my_data/S09.txt
/home/pin/my_data/S10.txt

Question 84

R

Reminder, what does :02 do in formatted string - (4)

e.g., b= 1
a = f’Fav number is {b:02}’
print(a)

Answer 84

:02 means that the formatted value should be displayed in at least two characters wide, and if the value is less than two digits, it will be zero-padded on the left side to reach the specified width.

For example:

If b is 1, then f’Fav number is {b:02}’ will result in ‘Fav number is 01’.

If b is 10, then f’Fav number is {b:02}’ will result in ‘Fav number is 10’.

Question 85

Comma-separated value (CSV) files are - (2)

Answer 85

plain-text files (meaning you can open them in a normal text editor and look at the data) where data items are separated by commas and where new sets of fields are placed on different lines (by means of a new-line character).

They are easy to understand.

Question 86

Example of CSV files

Answer 86

Wade,Alex,49

Smith,Joe,21

Doe,Jane, 23

West,Mae,29

Question 87

CSV files are common and can be

Answer 87

exported from spreadsheet software and are easy to read and write in just about all programming languages.

Question 88

What does the CSV module in Python facilitate? - (2)

Answer 88

The CSV module in Python facilitates the reading and writing of data from and to CSV (Comma-Separated Value) files.

It provides functions specifically designed to handle CSV file operations efficiently.

Question 89

How to import CSV module in python?

Answer 89

Type:
import csv

Question 90

What are the 3 modules that have in built CSV readers?

Answer 90

1. Pandas
2. Numpy
3. Python CSV module

Question 91

Explain this code - (6) that opens the entire CSV file

Answer 91

import csv: Imports the CSV module, allowing us to work with CSV files.

• ## with open('/content/sample_data/california_housing_test.csv', 'r') as csvfile:: Opens the CSV file in read mode (‘r’). The file path is provided in absolute format.
• reader = csv.reader(csvfile, delimiter=','): Creates a CSV reader object named reader.
• The delimiter=',' argument specifies that fields in the CSV file are separated by commas.
• for row in reader:: Iterates through each row in the CSV file
• print(', '.join(row)): Joins the items in the current row with commas and prints them

Question 92

What is PANDAS?

Answer 92

a Python module designed for reading in and processing data tables, it introduces a new data type called DataFrame

Question 93

Pandas is the most common and easiest way to

Answer 93

load in and process .CSV files

Question 94

Example of reading in csv folder in pandas:

Answer 94

Question 95

How about the average?

Explain this code - (3):

import pandas as pd
housingTable=pd.read_csv(‘/content/sample_data/california_housing_test.csv’)
housingTable.latitude

averageLatitude=housingTable.latitude.mean()
print(f’Mean latitude={averageLatitude:3.3f}’)

Answer 95

This Python code imports the Pandas library as ‘pd’ and reads a CSV file named ‘california_housing_test.csv’ located in the ‘/content/sample_data/’ directory.

The data from the CSV file is loaded into a Pandas DataFrame named ‘housingTable’.

Then, it calculates the mean latitude from the ‘latitude’ column of the DataFrame using the mean() function and prints it with 3 minium width (of entire string) and to 3 DP

Question 96

You can also convert dataframe (pandas) to something you are comfortable with like - (3)

Answer 96

a list

e.g., import pandas as pd
housingTable=pd.read_csv(‘/content/sample_data/california_housing_test.csv’)

housingList = housingTable.values.tolist()

Question 97

How about the average?

Explain what this code does - (6)

import pandas as pd
housingTable=pd.read_csv(‘/content/sample_data/california_housing_test.csv’)
housingTable.latitude

print(f’Mean lat: {housingTable.latitude.mean():3.3f}’)

housingList = housingTable.values.tolist()

latitude=housingTable[‘latitude’].tolist()

Answer 97

The code imports the Pandas library under the alias pd.

It reads a CSV file named california_housing_test.csv located in the specified path /content/sample_data/ into a Pandas DataFrame named housingTable.

It accesses the latitude column of the housingTable DataFrame.

It calculates the mean of the latitude column using the mean() method and prints it with prints it with 3 minium width (entire string) and to three decimal places.

It converts the DataFrame housingTable into a list of lists using the values.tolist() method and stores it in housingList.

It extracts all values from the latitude column of the housingTable DataFrame and converts them into a list stored in the variable latitude.