reading-notes
*Course 401 Python, Entry 19: Automation
How can you use regular expressions in Python to search for specific patterns in a string, and what is the primary module to work with them?
The primary Regex module is re. Start by import re.
Regex Functions
match() - Returns either a match object for a match, or None if there is no match. Only works starting from the beginning of the string.
search() - Returns the an input sequence for a match at any point in a string and returns a match object.
findall() - Finds all possible matches in sequence, returns as a list of strings.
finditer() - Returns more detailed location of matches, as an object.
group() - Selects out of the output match list some said element.
sub() - Finds and replaces according to a pattern. Takes replacement as second parameter.
subn() - Similar to sub(), but returns a tuple of replaced items.
Special characters
. - Wildcard.
^ - Matches according to start of the string.
$ - Matches according to end of the string.
[abc] - Matches according to set list of characters. Includes spreads such as [a-zA-Z0-9]
[^abc] - Exclusionary. Matches all not in the set.
\s - Space.
\w - Any single character, digit, or underscore.
\W - Matches any character not included under \w.
\s - Whitespace characters: space, newline, tab, return.
\S - Anything not \s.
\d - Digitis 0-9.
\D - Anything not \d
\t - Tab.
\n - Newline.
\r - Return.
\b - Beginning or ending of word.
+ - Repeats.
* - Greedy. Zero or more times of occurence.
? - Zero or one occurence.
*? - Limited greedy, until next defined character.
{x} - Repeats X number of times.
{x,} - Repeats X number of times or more.
{x, y} - Repeats between X through Y times.
() - Defines a grouping.
What is the purpose of the shutil module in Python, and provide an example of a common use case for file or directory management with this module?
Shutil is used for copying and archiving.
- Find a file via which().
- It can be used to copy file metadata.
- File permissions, copymode().
- Other metadata, copystat().
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Shutil can also be used to copy a directory via copytree().
- For file system management, information can be pulled up via disk_usage().
Compare and contrast the os and shutil modules. When would you choose to use one over the other?
The comparison for os an shutil simplifies down to os being used for simpler low-level operations, while shutil is for high-level more complex operations.
Things I want to know more about
Word from experience of when to use os vs shutil.