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Questions and Answers
What is the first step to average numeric values in a list?
What is the first step to average numeric values in a list?
Which method is used to write the contents of a list to a file?
Which method is used to write the contents of a list to a file?
How does list comprehension function in creating a new list?
How does list comprehension function in creating a new list?
What will happen if you do not include '
' when saving a list to a file?
What will happen if you do not include ' ' when saving a list to a file?
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What allows a function to return a list's contents?
What allows a function to return a list's contents?
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What is the primary distinction between a list and a tuple in Python?
What is the primary distinction between a list and a tuple in Python?
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What does the expression 'numbers * 2' return if 'numbers' is defined as follows: numbers = [1, 2, 3]?
What does the expression 'numbers * 2' return if 'numbers' is defined as follows: numbers = [1, 2, 3]?
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What happens if you attempt to insert an item at a negative index that specifies an invalid position?
What happens if you attempt to insert an item at a negative index that specifies an invalid position?
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When iterating over a list with a for loop, which statement is true?
When iterating over a list with a for loop, which statement is true?
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Which method removes the first occurrence of a specified item from a list?
Which method removes the first occurrence of a specified item from a list?
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What will be the output of the following code: print(list(range(5)))?
What will be the output of the following code: print(list(range(5)))?
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How can you access the last element of a list named 'items'?
How can you access the last element of a list named 'items'?
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When using the sort() method, what will be the order of the items in the list after execution?
When using the sort() method, what will be the order of the items in the list after execution?
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What occurs when you use the del statement with a valid index in a list?
What occurs when you use the del statement with a valid index in a list?
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What will result from executing 'print([10, 20, 30] + [40, 50])'?
What will result from executing 'print([10, 20, 30] + [40, 50])'?
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Which index would you use to access the third element of a list?
Which index would you use to access the third element of a list?
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Which of the following methods would you use to make a copy of each element in a list to a new list?
Which of the following methods would you use to make a copy of each element in a list to a new list?
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What is the result of attempting to call the index() method on an item that is not present in the list?
What is the result of attempting to call the index() method on an item that is not present in the list?
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Which of the following best describes 'list comprehension'?
Which of the following best describes 'list comprehension'?
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What does the reverse() method do to a list?
What does the reverse() method do to a list?
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What will be the effect of assigning one list to another list?
What will be the effect of assigning one list to another list?
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What will be the content of len_list after executing the code str_list = ['Winken', 'Blinken', 'Nod']
?
What will be the content of len_list after executing the code str_list = ['Winken', 'Blinken', 'Nod']
?
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What is the primary characteristic of a tuple in Python?
What is the primary characteristic of a tuple in Python?
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Which operation is NOT supported by tuples?
Which operation is NOT supported by tuples?
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What is the result of executing the code list2 = [item for item in list1 if item < 10]
with list1 = [1, 12, 2, 20, 3, 15, 4]
?
What is the result of executing the code list2 = [item for item in list1 if item < 10]
with list1 = [1, 12, 2, 20, 3, 15, 4]
?
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How is a two-dimensional list defined?
How is a two-dimensional list defined?
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What command would you use to convert a tuple to a list?
What command would you use to convert a tuple to a list?
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Which statement about list comprehensions is true?
Which statement about list comprehensions is true?
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What feature of matplotlib makes it suitable for data visualization?
What feature of matplotlib makes it suitable for data visualization?
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What does the len
function return when applied to a list?
What does the len
function return when applied to a list?
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Which of the following methods does NOT modify the original list?
Which of the following methods does NOT modify the original list?
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What will happen if an invalid index is used to access a list element?
What will happen if an invalid index is used to access a list element?
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How can you concatenate two lists in Python?
How can you concatenate two lists in Python?
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What does list slicing with a missing 'start' index default to?
What does list slicing with a missing 'start' index default to?
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When using the in
operator, what does it return if the item is not found in the list?
When using the in
operator, what does it return if the item is not found in the list?
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Which method would you use to add an item to the end of a list?
Which method would you use to add an item to the end of a list?
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Which of the following methods will raise a ValueError if the item is not found in the list?
Which of the following methods will raise a ValueError if the item is not found in the list?
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What does the insert(index, item)
method do?
What does the insert(index, item)
method do?
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Which slicing expression extracts elements starting from index 2 to 5 from a list?
Which slicing expression extracts elements starting from index 2 to 5 from a list?
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What must be done to use the matplotlib package in Python after installing it?
What must be done to use the matplotlib package in Python after installing it?
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Which of the following statements correctly demonstrates how to define the limits of the x-axis in a matplotlib graph?
Which of the following statements correctly demonstrates how to define the limits of the x-axis in a matplotlib graph?
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What is the first step to verify if matplotlib is installed correctly on your system?
What is the first step to verify if matplotlib is installed correctly on your system?
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Which command adds a point to a line graph using the plot function?
Which command adds a point to a line graph using the plot function?
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What does the yticks function do in matplotlib?
What does the yticks function do in matplotlib?
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In the provided Python code, which line is responsible for displaying the line graph?
In the provided Python code, which line is responsible for displaying the line graph?
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Which of the following is true about the coordinates used in the plot function?
Which of the following is true about the coordinates used in the plot function?
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What will happen if you run the command >>> import matplotlib and receive an error message?
What will happen if you run the command >>> import matplotlib and receive an error message?
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Study Notes
Lists and Tuples
- Lists are mutable sequences, meaning their elements can be changed after creation.
- Tuples are immutable sequences; elements cannot be changed after creation.
- Both are ordered collections of items.
- Lists use square brackets
[]
, while tuples use parentheses()
.
Introduction to Lists
- Lists are Python objects that hold various data items.
- Each item within a list is called an element.
- Lists can contain elements of different data types (e.g., numbers, strings).
- The
print()
function displays the entire list. - The
list()
function converts certain object types to a list.
Introduction to Lists (Continued)
- Lists can hold various data types like integers(e.g.,
[2, 4, 6, 8, 10]
) or strings (['Molly', 'Steven', 'Will', 'Alicia', 'Adriana']
). - A list item can be accessed using its index, starting from 0 for the first item.
- Negative indexes access elements from the end of a list (i.e., -1 is the last item, -2 is the second last item, and so on).
The Repetition Operator and Iterating over a List
- The
*
symbol is used to repeat a list or sequence a given number of times. - A
for
loop iterates through each element in a list. - The
len()
function returns the length (number of elements) of a sequence or list.
Indexing
- An index is a numerical value specifying an element's position in a list.
- The index of the first element is 0, the second is 1, and so on.
- Negative indexes identify an element's position relative to the end of the list. (e.g., -1 references the last item)
- Using invalid indexes (outsides the list's bounds) triggers an
IndexError
.
The len
function
- The
len()
function returns the number of items in a list. - Using
len(list)-1
finds the index of the last item. -
len()
can preventIndexError
when iterating over elements with a loop.
Lists Are Mutable
- List elements can be altered after creation.
- Assigning a new value to a specific list element using an valid index updates the list.
Concatenating Lists
- The
+
operator concatenates two lists. - The augmented assignment operator
+=
is used to ad a list to another list, instead of creating a new list.
List Slicing
- A slice extracts a segment of a sequence.
- Syntax
list[start:end]
. -
start
defaults to 0,end
defaults to the length of the source list. - Slices create copies of elements, not references; modifying a slice doesn't affect the original list.
- Slices support a
step
value to skip elements (e.g.,list[start:end:step]
). - Negative indexes count from the end of the list.
Finding Items in Lists with the in
Operator
- The
in
operator checks if a value exists within a list. - The
not in
operator checks if a value doesn't exist within a list.
List Methods and Useful Built-in Functions
-
append(item)
adds an item to the end of a list. -
index(item)
returns the index of the first occurrence ofitem
in a list (raisesValueError
if not found). -
insert(index, item)
insertsitem
at the specifiedindex
. -
sort()
sorts the list elements in ascending order. -
remove(item)
removes the first occurrence ofitem
. -
reverse()
reverses the list's order. -
del list[i]
removes an element at a specific index. -
min(list)
returns the item with the lowest value. -
max(list)
returns the item with the highest value.
Two-Dimensional Lists
- A two-dimensional list (nested list) is a list of lists.
- Useful for representing tables or matrices.
- Access elements using two indexes (row, column).
Tuples
- Tuples are immutable sequences; elements are fixed after creation.
- A tuple is defined using parentheses
()
instead of square brackets[]
. - Tuples support indexing, slicing,
len()
,min()
,max()
, and thein
operator, but not the methods likeappend
,insert
,sort
, orremove
. - Be sure to include a trailing comma when the tuple contains one element to avoid confusion with a simple expression (e.g.,
my_tuple = (1,)
).
Converting Tuples to Lists
- Use
list()
to convert a tuple to a list. - The resultant list can be modified unlike the source tuple.
matplotlib
- The
matplotlib
package provides functions for creating charts and graphs. - Install
matplotlib
separately from the standard Python library. - Use methods like
plt.plot()
,plt.bar()
, andplt.pie()
for various types of plotting.
Plotting a Line Graph
-
plt.plot(Xaxis_data, Yaxis_data)
connects data points to create a line. -
plt.show()
displays the graph. - Use
xlim()
andylim()
to set axes limits. - Use
xticks()
andyticks()
to control tick marks and labels.
Plotting a Bar Chart
-
plt.bar()
can be used to create bar charts. -
plt.show()
displays the chart. -
bar_width
, and tuple of color codes parameters (color
) can customize the chart.
Plotting Pie Charts
-
plt.pie()
function creates a pie chart. - Values are interpreted as percentages of the whole.
-
labels
parameter helps to label specific segments.
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Description
Test your knowledge on Python list operations with this quiz. It covers topics such as averaging numeric values, writing lists to files, and the functionality of list comprehension. Challenge yourself to see how well you understand these fundamental concepts in Python programming.