String
- Create
- Format
- Get
- Tests
- Substring
- Transform
- Grow
- Split
- Convert
Create
| What | How | Details |
| Empty | '' | |
| String literal | 'hello world' | |
| String literals (concatenate) | 'a' 'b' 'c' | |
| Concatenate strings | x + y | |
| From list with comma separator | ','.join(['a', 'b']) | |
| Object to string | str(x) | |
| What | How | Details |
| 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) | |
| 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' |
| Named formatting of whole number | 'a = '{num:,}'.format(num = int_var) | |
| 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)) | |
Get
| What | How | Details |
| Length | len(x) | |
| Find 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) | |
Tests
| What | How | Details |
| String | isinstance(x, str) | |
| Empty | if not x: | |
| Not empty | if x: | |
| Equal | x == y | |
| Contains substring | substr in x | |
| Does not contain substring | substr not in x | |
| Starts with | x.startswith(prefix) | |
| Ends with | x.endswith(suffix) | |
| Letters only | x.isalpha() | |
| Digits only | x.isdigit() | |
| Alphanumeric characters only | x.isalnum() | |
| Matches regex pattern | bool(re.search('\\w', 'abc')) | |
| Contains n regex substrings | len(re.findall('\\w', 'a. a')) == n | |
Substring
| What | How | Details |
| First character | x[0] | |
| Character i | 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') | |
| 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 |
| Remove prefix | x.removeprefix(y) | |
| Remove suffix | x.removesuffix(y) | |
| Remove substring | | |
| Remove regex group pattern | ? | |
| What | How | Details |
| Lower case | x.lower() | |
| Upper case | x.upper() | |
| Capitalize | x.capitalize() | |
| Map from dict | {'yes': 'ja', 'no': 'nee'}[x] | |
| Reverse | x[::-1] | |
Grow
| What | How | 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) | |
Split
| What | How | Details |
| Split string into two parts by separator (as triplet) | x.partition(sep) | |
| Split string into multiple parts by comma (as list) | x.split(sep=',') | |
| Split string into lines (as list) | x.splitlines() | |
Convert
| What | How | Details |
| Session hash | hash(x) | |
| To bytes | x.encode() | |
| To integer | int(x) | |
| To float | float(x) | |
| To date (unknown format) | pandas.to_datetime('2023 Jan 5') | Find better way |
| To date from known format | datetime.strptime('2023-12-31', '%Y-%m-%d') | |