Questions and Answers
What are strings?
Strings are a sequence of characters.
What is the purpose of the len() function in Python?
The len() function returns the length of a string.
Which characters can be considered special in a string?
A string is defined using unmatched quotation marks.
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What is the primary operator for concatenating strings in Python?
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To create a very long string across multiple lines, we use ______ quotes.
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What PEP provides a style guide for Python?
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What does indexing allow you to do in strings?
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In Python, the first character of a string is accessed with index 1.
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What is true about lists in Python?
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What operator is used to concatenate lists?
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What happens when you try to access an index in a string that does not exist?
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The method ______ returns a copy of the string with all uppercase letters.
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What does the split method return?
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What is the default delimiter used by the split method?
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How can the split method be useful?
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What does the statement name[5:10] return when name = 'John Cleese'?
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What is the outcome of the expression name[4:] if name = 'John Cleese'?
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What does the expression name[:-2] return for name = 'John Cleese'?
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In slicing, what are the default values for start, stop, and step if they are omitted?
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What is the primary functionality of the random module in Python?
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What does the random() function do?
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What is required to use a package/module in Python?
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Study Notes
Strings
- Strings are sequences of characters, which include alphabetical letters, numbers, symbols, and spaces.
- Strings can be defined with single quotes (' ') or double quotes (" "). Mixing quotes leads to syntax errors.
- Special characters like newline (\n) and tab (\t) can be used for formatting within strings. Escape characters are created with a backslash ().
- Long strings can be split across multiple lines using the continuation character () or enclosed in triple quotes (""" """).
- The
len()
function determines the length of a string, counting all characters including spaces and special characters.
Style
- PEP-8 outlines guidelines for writing readable Python code, emphasizing consistency.
- Emphasizes the importance of readability, stating "Code is read much more often than it is written."
- Comments in programs should include authorship, purpose, and modification history to enhance clarity.
Indexing
- Strings can be indexed to access individual characters; indexing starts at zero.
- Negative indexing allows accessing elements from the end of the string (-1 is the last character).
- For loops combined with
range()
can iterate over characters, allowing access to subranges or reversed sequences. - Using step in
range()
provides ability to skip certain characters while iterating.
Building and Operating on Strings
- Concatenation combines strings without automatic spacing; use '+' to join them.
- The print function outputs strings with an optional
sep
parameter to determine the separator andend
to specify trailing characters. - The
in
andnot in
operators check membership; methods likes.upper()
,s.lower()
, ands.replace()
alter string contents.
Lists
- Lists store collections of data, which can include different data types, including other lists.
- Lists maintain order, allow element access via indexing, and can be modified (adding, deleting).
- Python supports nested lists, where lists can contain other lists as elements.
- The
.split()
method transforms strings into lists based on specified delimiters; the default is a space.
Slicing
- Slicing permits accessing portions of strings or lists:
mystring[start:stop:step]
. - Omitting any part defaults to the entire string/list, with
start
defaulting to 0 andstop
to the length of the string/list. - Steps can be negative, allowing reverse slicing (e.g.,
name[::-1]
gives a reversed string).
Random Number Generation in Python
- The length of a slice for non-negative indices is determined by the difference between the two indices.
- The Python
random
module facilitates the generation of random numbers, including floating point numbers, integers, and selections from collections. - Random floating point numbers can be generated using the
random()
function, which produces values between 0 and 1. - Random integer generation can also be performed using functions within the
random
module.
Pseudorandom Numbers
- Pseudorandom number generators (PRNGs) create sequences that mimic randomness but are generated deterministically from an initial seed.
- Seeding a PRNG establishes a starting point for the sequence, ensuring reproducibility in random number generation.
- Good PRNGs exhibit characteristics like uniform distribution and long cycles before repeating values.
Random Selection
- Random selection from a series of items can be easily achieved with built-in functions in the
random
module. - Website random.org provides true random numbers based on atmospheric noise, distinguishing it from typical PRNGs which are algorithmically derived.
Utilizing Packages and Modules
- Python's functionality can be enhanced by importing packages and modules created by others, allowing access to a wider range of pre-written code.
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Description
This quiz covers the essential concepts of strings and lists in the context of the COMP1005/COMP5005 Fundamentals of Programming course. It includes topics such as string building and operations, indexing, slicing, and introduction to Monte Carlo techniques. Test your understanding of these foundational programming elements!