Reading experience of the book "Python Programming Quick Start (2nd Edition)" 1. String Operation
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This post was last edited by xinmeng_wit on 2024-4-24 21:40
1. Book Introduction
This book is a practical guide to Python programming for beginners. In fact, not only beginners, but also students who are familiar with Python and want to automate their daily work should read this book, which introduces a lot of Python programming skills and cases.
This book is divided into two parts. The first part introduces basic Python programming concepts (about 6 chapters), and the second part introduces some different tasks and automates work through Python programming (about 14 chapters), which is the focus of the book.
The first part, Python basics, takes up about 1/4 of the book, and the remaining 3/4 is about how to use Python to automate work, which is what attracts me to this book.
Chapter 1 talks about Python basics. Expressions, variable types, strings, etc.
Chapter 2 talks about Python's control flow;
Chapter 3 talks about functions;
Chapter 4 is about lists;
Chapter 5 talks about dictionaries;
Chapter 6 is about string operations.
The first five chapters are all about the basics of Python data types and syntax, which are relatively simple. For students with some programming knowledge, they only need to go through them briefly.
After reading Chapter 6, you will find that Python's string processing is very flexible and provides quite a lot of string processing methods, such as string indexing, slicing, searching, and conversion to lists or tuples.
Therefore, this article summarizes and extracts the string-related content explained in this book.
String Operations
1. String definitions can use single quotes (such as 'Hello World'), double quotes (such as "Hello World"), or triple quotes (such as '''Hello World''');
2. Available escape characters in Python
The following example:
3. Triple quotes can define multi-line strings and can also be used for comments
Multi-line string example:
Examples for annotations:
4. Strings can be indexed by subscript
The following example:
5. Strings can be sliced
The following example:
6. Strings can be matched
7. Strings can be placed inside other strings
Another way to write it:
The third way to write:
8. String methods upper(), lower(), isupper(), islower()
The upper() method converts all letters of a character to uppercase
The lower() method converts all letters in a string to lowercase
isupper() is used to check whether the string is all uppercase, and islower() is used to check whether the string is all lowercase.
9. isX() string method
10. Determine the start and end methods of a string: startswith(), endswith()
11. The join() method is used to connect a list of strings into a string
12. The split() method splits a string into a list of characters
13. The partition() method is used to divide a string into tuples (3 segments)
14. Use rjust(), ljust() and center() to align text
rjust(): right alignment
ljust(): Left alignment
center(): center alignment
15. Use strip(), rstrip() and lstrip() methods to remove whitespace characters
Whitespace characters are spaces, tabs, and newlines
strip(): remove all whitespace characters
rstrip(): remove whitespace characters on the right
lstrip(): remove blank characters on the left
16. Use ord() and chr() to convert between characters and numbers
Numbers are Unicode code points
In addition to the above string processing methods, there is also a more powerful operating system clipboard processing library pyperclip, which can copy and paste text on the system clipboard.
There are two examples in the book, one is to use the pyperclip library to quickly reply to messages, and the other is to quickly add specified content to text.
Quick reply message code:
#! python3
# mclip.py - A multi-clipboard program
TEXT = {'agree': """Yes, I agree. That sounds fine to me.""",
'busy': """Sorry, can we do this later this week or next week?""",
'upsell': """Would you consider making this a monthly donation?"""}
import sys, pyperclip
if len(sys.argv) < 2:
print('Usage: py mclip.py [keyphrase] - copy phrase text')
sys.exit()
keyphrase = sys.argv[1] # first command line arg is the keyphrase
if keyphrase in TEXT:
pyperclip.copy(TEXT[keyphrase])
print('Text for ' + keyphrase + ' copied to clipboard.')
else:
print('There is no text for ' + keyphrase)
operation result:
After execution is completed, the text "Yes, I agree. That sounds fine to me." will be copied to the system clipboard and then pasted directly to where it is needed. This way, you don't have to type the text by hand, and you can quickly copy the text.
Quickly add the specified content code to the text:
#! python3
# bulletPointAdder.py - Adds wikipedia bullet points to the start
# of each line of text on the clipboard
import pyperclip
text = pyperclip.paste()
# Separate lines and add stars.
lines = text.split('\n')
for i in range(len(lines)): # loop through all indexes for "lines" list
lines[i] = '*' + lines[i] # add star to each string in "lines" lists
text = '\n'.join(lines)
pyperclip.copy(text)
The purpose of this code is to read the contents of the system clipboard and then add an asterisk (*) in front of each paragraph of text before copying it to the clipboard, so that the text can be quickly changed.
Through the study of this chapter, you have mastered various string processing methods, which are very useful. I believe that they will definitely be used in the later practical courses, and they will achieve twice the result with half the effort.
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