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# string
> 
# module pixeltable.functions.string
Pixeltable UDFs for `StringType`.
It closely follows the Pandas `pandas.Series.str` API.
Example:
```python theme={null}
import pixeltable as pxt
t = pxt.get_table(...)
t.select(t.str_col.capitalize()).collect()
```
## iterator string\_splitter()
```python Signature theme={null}
@pxt.iterator
string_splitter(
text: pxt.String,
separators: pxt.String,
*,
spacy_model: pxt.String = 'en_core_web_sm'
)
```
Iterator over chunks of a string. The string is chunked according to the specified `separators`.
**Outputs**:
One row per chunk, with the following columns:
* `text` (`pxt.String`): The text of the chunk.
**Parameters:**
* **`separators`** (`pxt.String`): Separators to use to chunk the document. Currently the only supported option is `'sentence'`.
* **`spacy_model`** (`pxt.String`): Name of the spaCy model to use for sentence segmentation.
**Examples:**
This example assumes an existing table `tbl` with a column `text` of type `pxt.String`. Create a view that splits all strings on sentence boundaries:
```python theme={null}
pxt.create_view(
'sentence_chunks',
tbl,
iterator=string_splitter(tbl.text, separators='sentence'),
)
```
## udf capitalize()
```python Signature theme={null}
@pxt.udf
capitalize(self: pxt.String) -> pxt.String
```
Return string with its first character capitalized and the rest lowercased.
Equivalent to [`str.capitalize()`](https://docs.python.org/3/library/stdtypes.html#str.capitalize).
## udf casefold()
```python Signature theme={null}
@pxt.udf
casefold(self: pxt.String) -> pxt.String
```
Return a casefolded copy of string.
Equivalent to [`str.casefold()`](https://docs.python.org/3/library/stdtypes.html#str.casefold).
## udf center()
```python Signature theme={null}
@pxt.udf
center(
self: pxt.String,
width: pxt.Int,
fillchar: pxt.String = ' '
) -> pxt.String
```
Return a centered string of length `width`.
Equivalent to [`str.center()`](https://docs.python.org/3/library/stdtypes.html#str.center).
**Parameters:**
* **`width`** (`pxt.Int`): Total width of the resulting string.
* **`fillchar`** (`pxt.String`): Character used for padding.
## udf contains()
```python Signature theme={null}
@pxt.udf
contains(
self: pxt.String,
substr: pxt.String,
case: pxt.Bool = True
) -> pxt.Bool
```
Test if string contains a substring.
**Parameters:**
* **`substr`** (`pxt.String`): string literal or regular expression
* **`case`** (`pxt.Bool`): if False, ignore case
## udf contains\_re()
```python Signature theme={null}
@pxt.udf
contains_re(
self: pxt.String,
pattern: pxt.String,
flags: pxt.Int = 0
) -> pxt.Bool
```
Test if string contains a regular expression pattern.
**Parameters:**
* **`pattern`** (`pxt.String`): regular expression pattern
* **`flags`** (`pxt.Int`): [flags](https://docs.python.org/3/library/re.html#flags) for the `re` module
## udf count()
```python Signature theme={null}
@pxt.udf
count(
self: pxt.String,
pattern: pxt.String,
flags: pxt.Int = 0
) -> pxt.Int
```
Count occurrences of pattern or regex.
**Parameters:**
* **`pattern`** (`pxt.String`): string literal or regular expression
* **`flags`** (`pxt.Int`): [flags](https://docs.python.org/3/library/re.html#flags) for the `re` module
## udf endswith()
```python Signature theme={null}
@pxt.udf
endswith(self: pxt.String, substr: pxt.String) -> pxt.Bool
```
Return `True` if the string ends with the specified suffix, otherwise return `False`.
Equivalent to [`str.endswith()`](https://docs.python.org/3/library/stdtypes.html#str.endswith).
**Parameters:**
* **`substr`** (`pxt.String`): string literal
## udf fill()
```python Signature theme={null}
@pxt.udf
fill(self: pxt.String, width: pxt.Int, **kwargs) -> pxt.String
```
Wraps the single paragraph in string, and returns a single string containing the wrapped paragraph.
Equivalent to [`textwrap.fill()`](https://docs.python.org/3/library/textwrap.html#textwrap.fill).
**Parameters:**
* **`width`** (`pxt.Int`): Maximum line width.
* **`kwargs`** (`Any`): Additional keyword arguments to pass to `textwrap.fill()`.
## udf find()
```python Signature theme={null}
@pxt.udf
find(
self: pxt.String,
substr: pxt.String,
start: pxt.Int = 0,
end: pxt.Int | None = None
) -> pxt.Int
```
Return the lowest index in string where `substr` is found within the slice `s[start:end]`.
Equivalent to [`str.find()`](https://docs.python.org/3/library/stdtypes.html#str.find).
**Parameters:**
* **`substr`** (`pxt.String`): substring to search for
* **`start`** (`pxt.Int`): slice start
* **`end`** (`pxt.Int | None`): slice end
## udf findall()
```python Signature theme={null}
@pxt.udf
findall(
self: pxt.String,
pattern: pxt.String,
flags: pxt.Int = 0
) -> pxt.Json[(Json, ...)]
```
Find all occurrences of a regular expression pattern in string.
Equivalent to [`re.findall()`](https://docs.python.org/3/library/re.html#re.findall).
**Parameters:**
* **`pattern`** (`pxt.String`): regular expression pattern
* **`flags`** (`pxt.Int`): [flags](https://docs.python.org/3/library/re.html#flags) for the `re` module
## udf format()
```python Signature theme={null}
@pxt.udf
format(self: pxt.String, *args, **kwargs) -> pxt.String
```
Perform string formatting.
Equivalent to [`str.format()`](https://docs.python.org/3/library/stdtypes.html#str.format).
## udf fullmatch()
```python Signature theme={null}
@pxt.udf
fullmatch(
self: pxt.String,
pattern: pxt.String,
case: pxt.Bool = True,
flags: pxt.Int = 0
) -> pxt.Bool
```
Determine if string fully matches a regular expression.
Equivalent to [`re.fullmatch()`](https://docs.python.org/3/library/re.html#re.fullmatch).
**Parameters:**
* **`pattern`** (`pxt.String`): regular expression pattern
* **`case`** (`pxt.Bool`): if False, ignore case
* **`flags`** (`pxt.Int`): [flags](https://docs.python.org/3/library/re.html#flags) for the `re` module
## udf index()
```python Signature theme={null}
@pxt.udf
index(
self: pxt.String,
substr: pxt.String,
start: pxt.Int = 0,
end: pxt.Int | None = None
) -> pxt.Int
```
Return the lowest index in string where `substr` is found within the slice `[start:end]`.
Raises ValueError if `substr` is not found.
Equivalent to [`str.index()`](https://docs.python.org/3/library/stdtypes.html#str.index).
**Parameters:**
* **`substr`** (`pxt.String`): substring to search for
* **`start`** (`pxt.Int`): slice start
* **`end`** (`pxt.Int | None`): slice end
## udf isalnum()
```python Signature theme={null}
@pxt.udf
isalnum(self: pxt.String) -> pxt.Bool
```
Return `True` if all characters in the string are alphanumeric and there is at least one character, `False`
otherwise.
Equivalent to \[`str.isalnum()`]\([https://docs.python.org/3/library/stdtypes.html#str.isalnum](https://docs.python.org/3/library/stdtypes.html#str.isalnum)
## udf isalpha()
```python Signature theme={null}
@pxt.udf
isalpha(self: pxt.String) -> pxt.Bool
```
Return `True` if all characters in the string are alphabetic and there is at least one character, `False` otherwise.
Equivalent to [`str.isalpha()`](https://docs.python.org/3/library/stdtypes.html#str.isalpha).
## udf isascii()
```python Signature theme={null}
@pxt.udf
isascii(self: pxt.String) -> pxt.Bool
```
Return `True` if the string is empty or all characters in the string are ASCII, `False` otherwise.
Equivalent to [`str.isascii()`](https://docs.python.org/3/library/stdtypes.html#str.isascii).
## udf isdecimal()
```python Signature theme={null}
@pxt.udf
isdecimal(self: pxt.String) -> pxt.Bool
```
Return `True` if all characters in the string are decimal characters and there is at least one character, `False`
otherwise.
Equivalent to [`str.isdecimal()`](https://docs.python.org/3/library/stdtypes.html#str.isdecimal).
## udf isdigit()
```python Signature theme={null}
@pxt.udf
isdigit(self: pxt.String) -> pxt.Bool
```
Return `True` if all characters in the string are digits and there is at least one character, `False` otherwise.
Equivalent to [`str.isdigit()`](https://docs.python.org/3/library/stdtypes.html#str.isdigit).
## udf isidentifier()
```python Signature theme={null}
@pxt.udf
isidentifier(self: pxt.String) -> pxt.Bool
```
Return `True` if the string is a valid identifier according to the language definition, `False` otherwise.
Equivalent to [`str.isidentifier()`](https://docs.python.org/3/library/stdtypes.html#str.isidentifier)
## udf islower()
```python Signature theme={null}
@pxt.udf
islower(self: pxt.String) -> pxt.Bool
```
Return `True` if all cased characters in the string are lowercase and there is at least one cased character,
`False` otherwise.
Equivalent to [`str.islower()`](https://docs.python.org/3/library/stdtypes.html#str.islower)
## udf isnumeric()
```python Signature theme={null}
@pxt.udf
isnumeric(self: pxt.String) -> pxt.Bool
```
Return `True` if all characters in the string are numeric characters, `False` otherwise.
Equivalent to [`str.isnumeric()`](https://docs.python.org/3/library/stdtypes.html#str.isnumeric)
## udf isspace()
```python Signature theme={null}
@pxt.udf
isspace(self: pxt.String) -> pxt.Bool
```
Return `True` if there are only whitespace characters in the string and there is at least one character,
`False` otherwise.
Equivalent to [`str.isspace()`](https://docs.python.org/3/library/stdtypes.html#str.isspace)
## udf istitle()
```python Signature theme={null}
@pxt.udf
istitle(self: pxt.String) -> pxt.Bool
```
Return `True` if the string is a titlecased string and there is at least one character, `False` otherwise.
Equivalent to [`str.istitle()`](https://docs.python.org/3/library/stdtypes.html#str.istitle)
## udf isupper()
```python Signature theme={null}
@pxt.udf
isupper(self: pxt.String) -> pxt.Bool
```
Return `True` if all cased characters in the string are uppercase and there is at least one cased character,
`False` otherwise.
Equivalent to [`str.isupper()`](https://docs.python.org/3/library/stdtypes.html#str.isupper)
## udf join()
```python Signature theme={null}
@pxt.udf
join(sep: pxt.String, elements: pxt.Json[(Json) -> pxt.String
```
Return a string which is the concatenation of the strings in `elements`.
Equivalent to [`str.join()`](https://docs.python.org/3/library/stdtypes.html#str.join)
## udf len()
```python Signature theme={null}
@pxt.udf
len(self: pxt.String) -> pxt.Int
```
Return the number of characters in the string.
Equivalent to [`len(str)`](https://docs.python.org/3/library/functions.html#len)
## udf ljust()
```python Signature theme={null}
@pxt.udf
ljust(
self: pxt.String,
width: pxt.Int,
fillchar: pxt.String = ' '
) -> pxt.String
```
Return the string left-justified in a string of length `width`.
Equivalent to [`str.ljust()`](https://docs.python.org/3/library/stdtypes.html#str.ljust)
**Parameters:**
* **`width`** (`pxt.Int`): Minimum width of resulting string; additional characters will be filled with character defined in
`fillchar`.
* **`fillchar`** (`pxt.String`): Additional character for filling.
## udf lower()
```python Signature theme={null}
@pxt.udf
lower(self: pxt.String) -> pxt.String
```
Return a copy of the string with all the cased characters converted to lowercase.
Equivalent to [`str.lower()`](https://docs.python.org/3/library/stdtypes.html#str.lower)
## udf lstrip()
```python Signature theme={null}
@pxt.udf
lstrip(
self: pxt.String,
chars: pxt.String | None = None
) -> pxt.String
```
Return a copy of the string with leading characters removed. The `chars` argument is a string specifying the set of
characters to be removed. If omitted or `None`, whitespace characters are removed.
Equivalent to [`str.lstrip()`](https://docs.python.org/3/library/stdtypes.html#str.lstrip)
**Parameters:**
* **`chars`** (`pxt.String | None`): The set of characters to be removed.
## udf match()
```python Signature theme={null}
@pxt.udf
match(
self: pxt.String,
pattern: pxt.String,
case: pxt.Bool = True,
flags: pxt.Int = 0
) -> pxt.Bool
```
Determine if string starts with a match of a regular expression
**Parameters:**
* **`pattern`** (`pxt.String`): regular expression pattern
* **`case`** (`pxt.Bool`): if False, ignore case
* **`flags`** (`pxt.Int`): [flags](https://docs.python.org/3/library/re.html#flags) for the `re` module
## udf normalize()
```python Signature theme={null}
@pxt.udf
normalize(self: pxt.String, form: pxt.String) -> pxt.String
```
Return the Unicode normal form.
Equivalent to [`unicodedata.normalize()`](https://docs.python.org/3/library/unicodedata.html#unicodedata.normalize)
**Parameters:**
* **`form`** (`pxt.String`): Unicode normal form (`'NFC'`, `'NFKC'`, `'NFD'`, `'NFKD'`)
## udf pad()
```python Signature theme={null}
@pxt.udf
pad(
self: pxt.String,
width: pxt.Int,
side: pxt.String = 'left',
fillchar: pxt.String = ' '
) -> pxt.String
```
Pad string up to width
**Parameters:**
* **`width`** (`pxt.Int`): Minimum width of resulting string; additional characters will be filled with character defined in
`fillchar`.
* **`side`** (`pxt.String`): Side from which to fill resulting string (`'left'`, `'right'`, `'both'`)
* **`fillchar`** (`pxt.String`): Additional character for filling
## udf partition()
```python Signature theme={null}
@pxt.udf
partition(
self: pxt.String,
sep: pxt.String = ' '
) -> pxt.Json[(Json, ...)]
```
Splits string at the first occurrence of `sep`, and returns 3 elements containing the part before the
separator, the separator itself, and the part after the separator. If the separator is not found, return 3 elements
containing string itself, followed by two empty strings.
## udf removeprefix()
```python Signature theme={null}
@pxt.udf
removeprefix(self: pxt.String, prefix: pxt.String) -> pxt.String
```
Remove prefix. If the prefix is not present, returns string.
## udf removesuffix()
```python Signature theme={null}
@pxt.udf
removesuffix(self: pxt.String, suffix: pxt.String) -> pxt.String
```
Remove suffix. If the suffix is not present, returns string.
## udf repeat()
```python Signature theme={null}
@pxt.udf
repeat(self: pxt.String, n: pxt.Int) -> pxt.String
```
Repeat string `n` times.
## udf replace()
```python Signature theme={null}
@pxt.udf
replace(
self: pxt.String,
substr: pxt.String,
repl: pxt.String,
n: pxt.Int | None = None
) -> pxt.String
```
Replace occurrences of `substr` with `repl`.
Equivalent to [`str.replace()`](https://docs.python.org/3/library/stdtypes.html#str.replace).
**Parameters:**
* **`substr`** (`pxt.String`): string literal
* **`repl`** (`pxt.String`): replacement string
* **`n`** (`pxt.Int | None`): number of replacements to make (if `None`, replace all occurrences)
## udf replace\_re()
```python Signature theme={null}
@pxt.udf
replace_re(
self: pxt.String,
pattern: pxt.String,
repl: pxt.String,
n: pxt.Int | None = None,
flags: pxt.Int = 0
) -> pxt.String
```
Replace occurrences of a regular expression pattern with `repl`.
Equivalent to [`re.sub()`](https://docs.python.org/3/library/re.html#re.sub).
**Parameters:**
* **`pattern`** (`pxt.String`): regular expression pattern
* **`repl`** (`pxt.String`): replacement string
* **`n`** (`pxt.Int | None`): number of replacements to make (if `None`, replace all occurrences)
* **`flags`** (`pxt.Int`): [flags](https://docs.python.org/3/library/re.html#flags) for the `re` module
## udf reverse()
```python Signature theme={null}
@pxt.udf
reverse(self: pxt.String) -> pxt.String
```
Return a reversed copy of the string.
Equivalent to `str[::-1]`.
## udf rfind()
```python Signature theme={null}
@pxt.udf
rfind(
self: pxt.String,
substr: pxt.String,
start: pxt.Int | None = 0,
end: pxt.Int | None = None
) -> pxt.Int
```
Return the highest index where `substr` is found, such that `substr` is contained within `[start:end]`.
Equivalent to [`str.rfind()`](https://docs.python.org/3/library/stdtypes.html#str.rfind).
**Parameters:**
* **`substr`** (`pxt.String`): substring to search for
* **`start`** (`pxt.Int | None`): slice start
* **`end`** (`pxt.Int | None`): slice end
## udf rindex()
```python Signature theme={null}
@pxt.udf
rindex(
self: pxt.String,
substr: pxt.String,
start: pxt.Int | None = 0,
end: pxt.Int | None = None
) -> pxt.Int
```
Return the highest index where `substr` is found, such that `substr` is contained within `[start:end]`.
Raises ValueError if `substr` is not found.
Equivalent to [`str.rindex()`](https://docs.python.org/3/library/stdtypes.html#str.rindex).
## udf rjust()
```python Signature theme={null}
@pxt.udf
rjust(
self: pxt.String,
width: pxt.Int,
fillchar: pxt.String = ' '
) -> pxt.String
```
Return the string right-justified in a string of length `width`.
Equivalent to [`str.rjust()`](https://docs.python.org/3/library/stdtypes.html#str.rjust).
**Parameters:**
* **`width`** (`pxt.Int`): Minimum width of resulting string.
* **`fillchar`** (`pxt.String`): Additional character for filling.
## udf rpartition()
```python Signature theme={null}
@pxt.udf
rpartition(
self: pxt.String,
sep: pxt.String = ' '
) -> pxt.Json[(Json, ...)]
```
This method splits string at the last occurrence of `sep`, and returns a list containing the part before the
separator, the separator itself, and the part after the separator.
## udf rstrip()
```python Signature theme={null}
@pxt.udf
rstrip(
self: pxt.String,
chars: pxt.String | None = None
) -> pxt.String
```
Return a copy of string with trailing characters removed.
Equivalent to [`str.rstrip()`](https://docs.python.org/3/library/stdtypes.html#str.rstrip).
**Parameters:**
* **`chars`** (`pxt.String | None`): The set of characters to be removed. If omitted or `None`, whitespace characters are removed.
## udf slice()
```python Signature theme={null}
@pxt.udf
slice(
self: pxt.String,
start: pxt.Int | None = None,
stop: pxt.Int | None = None,
step: pxt.Int | None = None
) -> pxt.String
```
Return a slice.
**Parameters:**
* **`start`** (`pxt.Int | None`): slice start
* **`stop`** (`pxt.Int | None`): slice end
* **`step`** (`pxt.Int | None`): slice step
## udf slice\_replace()
```python Signature theme={null}
@pxt.udf
slice_replace(
self: pxt.String,
start: pxt.Int | None = None,
stop: pxt.Int | None = None,
repl: pxt.String | None = None
) -> pxt.String
```
Replace a positional slice with another value.
**Parameters:**
* **`start`** (`pxt.Int | None`): slice start
* **`stop`** (`pxt.Int | None`): slice end
* **`repl`** (`pxt.String | None`): replacement value
## udf startswith()
```python Signature theme={null}
@pxt.udf
startswith(self: pxt.String, substr: pxt.String) -> pxt.Int
```
Return `True` if string starts with `substr`, otherwise return `False`.
Equivalent to [`str.startswith()`](https://docs.python.org/3/library/stdtypes.html#str.startswith).
**Parameters:**
* **`substr`** (`pxt.String`): string literal
## udf strip()
```python Signature theme={null}
@pxt.udf
strip(
self: pxt.String,
chars: pxt.String | None = None
) -> pxt.String
```
Return a copy of string with leading and trailing characters removed.
Equivalent to [`str.strip()`](https://docs.python.org/3/library/stdtypes.html#str.strip).
**Parameters:**
* **`chars`** (`pxt.String | None`): The set of characters to be removed. If omitted or `None`, whitespace characters are removed.
## udf swapcase()
```python Signature theme={null}
@pxt.udf
swapcase(self: pxt.String) -> pxt.String
```
Return a copy of string with uppercase characters converted to lowercase and vice versa.
Equivalent to [`str.swapcase()`](https://docs.python.org/3/library/stdtypes.html#str.swapcase).
## udf title()
```python Signature theme={null}
@pxt.udf
title(self: pxt.String) -> pxt.String
```
Return a titlecased version of string, i.e. words start with uppercase characters, all remaining cased characters
are lowercase.
Equivalent to [`str.title()`](https://docs.python.org/3/library/stdtypes.html#str.title).
## udf upper()
```python Signature theme={null}
@pxt.udf
upper(self: pxt.String) -> pxt.String
```
Return a copy of string converted to uppercase.
Equivalent to [`str.upper()`](https://docs.python.org/3/library/stdtypes.html#str.upper).
## udf wrap()
```python Signature theme={null}
@pxt.udf
wrap(
self: pxt.String,
width: pxt.Int,
**kwargs
) -> pxt.Json[(String, ...)]
```
Wraps the single paragraph in string so every line is at most `width` characters long.
Returns a list of output lines, without final newlines.
Equivalent to [`textwrap.fill()`](https://docs.python.org/3/library/textwrap.html#textwrap.fill).
**Parameters:**
* **`width`** (`pxt.Int`): Maximum line width.
* **`kwargs`** (`Any`): Additional keyword arguments to pass to `textwrap.fill()`.
## udf zfill()
```python Signature theme={null}
@pxt.udf
zfill(self: pxt.String, width: pxt.Int) -> pxt.String
```
Pad a numeric string with ASCII `0` on the left to a total length of `width`.
Equivalent to [`str.zfill()`](https://docs.python.org/3/library/stdtypes.html#str.zfill).
**Parameters:**
* **`width`** (`pxt.Int`): Minimum width of resulting string.
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