String

String handling

Code

import string

Constants

Action	Code	Details
Lowercase and uppercase letters	string.ascii_letters	abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
Lowercase letters	string.ascii_lowercase	abcdefghijklmnopqrstuvwxyz
Uppercase letters	string.ascii_uppercase	ABCDEFGHIJKLMNOPQRSTUVWXYZ
Digits	string.digits	0123456789
Hexadecimal digits	string.hexdigits	0123456789abcdefABCDEF
Whitespace characters	string.whitespace	Includes space, tab, linefeed, return, formfeed, and vertical tab.
Punctuation characters	string.punctuation	!"#$%&'()*+,-./:;<=>?@[]^_`{|}~
Printable characters	string.printable	Combination of digits, letters, punctuation, and whitespace.

Create

Action	Code	Details
Empty	''
Literal	'hello world'
Literals (concatenate)	'a' 'b' 'c'
Random lowercase string of length n	''.join(random.choices(string.ascii_lowercase + string.digits, k=n))
Random alphanumeric string of length n	''.join(random.choices(string.ascii_lowercase + string.digits, k=n))
From list, separated by comma	','.join(['a', 'b'])
Object to string	str(x)
Positional formatting	'First {0} then {1}'.format(1 + 1, 2 * 2)
Named formatting	'First {sum} then {mult}'.format(sum = 1 + 1, mult = 2 * 2)
Named element formatting	'a0 = {a[0]}'.format(a=[1,2])
Named attribute formatting	'Instance is of type: {p.type}'.format(p=Prop)
Named formatting of whole number	'a = '{num:,}'.format(num = int_var)
Dynamic formatting based on dict	'Value of a and b is {a} and {b}'.format_map(dict(a=1, b=2))
Whole number	'a = {:d}'.format(3)
Whole number with thousands separator	'a = {:,d}'.format(1000)	Outputs '1,000'
Padded whole number	'a = {:3d}'.format(3)	Outputs ' 3'
Zero-padded whole number	'a = {:03d}'.format(3)	Outputs '003'
Float	'a = {:f}'.format(3.14)
Float as whole number	'a = {:.0f}'.format(3.14)	Outputs '3'
Float with decimal-point padding	'a = {:06.2f}'.format(3.1234)
Datetime with format	'{:%Y-%m-%d %H:%M}'.format(datetime(2001, 2, 3, 4, 5))

Test

Action	Code	Details
Is str	type(x) is str
Is string (str or subclass)	isinstance(x, str)
Empty	not x
Not empty	x
Equal	x == y
Contains substring	substr in x
Letters only	x.isalpha()
Digits only	x.isdigit()
Alphanumeric characters only	x.isalnum()
Does not contain substring	substr not in x
Starts with	x.startswith(prefix)
Ends with	x.endswith(suffix)
Matches regex pattern	bool(re.search('\w', 'abc'))
Contains n regex substrings	len(re.findall('\w', 'a. a')) == n

Extract

Action	Code	Details
Number of characters (length)	len(x)	? how is this handled for unicode ?
Session hash	hash(x)
Find first index of substring	x.index(substr)	Raises error if not found
Try find index of substring	x.find(substr)
Try find last index of substring	x.rfind(substr)
Count number of non-overlapping substring occurrences	x.count(substr)
Count number of non-overlapping substring occurrences in range [n, m]	x.count(substr, n, m)

Derive

Action	Code	Details
Remove substring	?
Remove regex group pattern	?

Transform the string whilst preserving length

Action	Code	Details
Lower case	x.lower()
Upper case	x.upper()
Capitalize	x.capitalize()
Map from dict	{'yes': 'ja', 'no': 'nee'}[x]

Order

Action	Code	Details
Reverse characters	x[::-1]

Expand string

Action	Code	Details
Left-pad to length n	x.ljust(n)
Right-pad to length n	x.rjust(n)
Left-right padding to length n	x.center(n)
Replicate n times	x * n
Concatenate	x + y
Join with iterable	x.join(iter)

Substring

Action	Code	Details
First character	x[0]
_i_th character	x[i]	Index beyond length will raise error
Last character	x[-1]
Substring (slice)	x[2:3]
First n characters	x[:n]
Last n characters	x[-n:]
Strip leading whitespace	x.strip()
Strip leading characters	x.strip('abc')
Remove prefix	x.removeprefix(y)
Remove suffix	x.removesuffix(y)
Substring up to first occurrence of y	x.split(y)[0]	y is excluded
Substring up to first line break	x.split('\n')[0]	Line break is excluded

Combine

Action	Code	Details
Concatenate strings	x + y

Convert

Action	Code	Details
To bytes	x.encode()
Parse as integer	int(x)
Parse as float	float(x)
Parse date (unknown format)	pandas.to_datetime('2023 Jan 5')
To date from YY-MM-DD format	datetime.strptime('2023-12-31', '%Y-%m-%d')

Convert to list of substrings

Action	Code	Details
Split string into two parts by separator (as triplet)	x.partition(sep)
Split string into multiple parts by separator sep (as list)	x.split(sep)
Split string into lines (as list)	x.splitlines()
Split string into cumulative parts by separator sep (as list)	list(itertools.accumulate(x.split(sep), lambda x, y: sep.join([x, y])))	For sep='.', a.b.c becomes [a, a.b, a.b.c]