Class: Polars::StringNameSpace

Inherits:
Object
  • Object
show all
Defined in:
lib/polars/string_name_space.rb

Overview

Series.str namespace.

Instance Method Summary collapse

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class Polars::ExprDispatch

Instance Method Details

#contains(pattern, literal: false) ⇒ Series

Check if strings in Series contain a substring that matches a regex.

Examples:

s = Polars::Series.new(["Crab", "cat and dog", "rab$bit", nil])
s.str.contains("cat|bit")
# =>
# shape: (4,)
# Series: '' [bool]
# [
#         false
#         true
#         true
#         null
# ]
s.str.contains("rab$", literal: true)
# =>
# shape: (4,)
# Series: '' [bool]
# [
#         false
#         false
#         true
#         null
# ]

Parameters:

  • pattern (String) —

    A valid regex pattern.

  • literal (Boolean) (defaults to: false) —

    Treat pattern as a literal string.

Returns:



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# File 'lib/polars/string_name_space.rb', line 290

def contains(pattern, literal: false)
  super
end

#count_match(pattern) ⇒ Series

Count all successive non-overlapping regex matches.

Examples:

s = Polars::Series.new("foo", ["123 bla 45 asd", "xyz 678 910t"])
s.str.count_match('\d')
# =>
# shape: (2,)
# Series: 'foo' [u32]
# [
#         5
#         6
# ]

Parameters:

  • pattern (String) —

    A valid regex pattern

Returns:



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# File 'lib/polars/string_name_space.rb', line 488

def count_match(pattern)
  super
end

#decode(encoding, strict: false) ⇒ Series

Decode a value using the provided encoding.

Examples:

s = Polars::Series.new(["666f6f", "626172", nil])
s.str.decode("hex")
# =>
# shape: (3,)
# Series: '' [binary]
# [
#         b"foo"
#         b"bar"
#         null
# ]

Parameters:

  • encoding ("hex", "base64") —

    The encoding to use.

  • strict (Boolean) (defaults to: false) —

    How to handle invalid inputs:

    • true: An error will be thrown if unable to decode a value.
    • false: Unhandled values will be replaced with nil.

Returns:



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# File 'lib/polars/string_name_space.rb', line 361

def decode(encoding, strict: false)
  super
end

#encode(encoding) ⇒ Series

Encode a value using the provided encoding.

Examples:

s = Polars::Series.new(["foo", "bar", nil])
s.str.encode("hex")
# =>
# shape: (3,)
# Series: '' [str]
# [
#         "666f6f"
#         "626172"
#         null
# ]

Parameters:

  • encoding ("hex", "base64") —

    The encoding to use.

Returns:



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# File 'lib/polars/string_name_space.rb', line 383

def encode(encoding)
  super
end

#ends_with(sub) ⇒ Series

Check if string values end with a substring.

Examples:

s = Polars::Series.new("fruits", ["apple", "mango", nil])
s.str.ends_with("go")
# =>
# shape: (3,)
# Series: 'fruits' [bool]
# [
#         false
#         true
#         null
# ]

Parameters:

  • sub (String) —

    Suffix substring.

Returns:



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# File 'lib/polars/string_name_space.rb', line 312

def ends_with(sub)
  super
end

#extract(pattern, group_index: 1) ⇒ Series

Extract the target capture group from provided patterns.

Examples:

df = Polars::DataFrame.new({"foo" => ["123 bla 45 asd", "xyz 678 910t"]})
df.select([Polars.col("foo").str.extract('(\d+)')])
# =>
# shape: (2, 1)
# ┌─────┐
# │ foo │
# │ --- │
# │ str │
# ╞═════╡
# │ 123 │
# │ 678 │
# └─────┘

Parameters:

  • pattern (String) —

    A valid regex pattern

  • group_index (Integer) (defaults to: 1) —

    Index of the targeted capture group. Group 0 mean the whole pattern, first group begin at index 1 Default to the first capture group

Returns:



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# File 'lib/polars/string_name_space.rb', line 443

def extract(pattern, group_index: 1)
  super
end

#extract_all(pattern) ⇒ Series

Extracts all matches for the given regex pattern.

Extract each successive non-overlapping regex match in an individual string as an array

Examples:

s = Polars::Series.new("foo", ["123 bla 45 asd", "xyz 678 910t"])
s.str.extract_all('(\d+)')
# =>
# shape: (2,)
# Series: 'foo' [list[str]]
# [
#         ["123", "45"]
#         ["678", "910"]
# ]

Parameters:

  • pattern (String) —

    A valid regex pattern

Returns:



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# File 'lib/polars/string_name_space.rb', line 467

def extract_all(pattern)
  super
end

#join(delimiter = "-", ignore_nulls: true) ⇒ Series Also known as: concat

Vertically concat the values in the Series to a single string value.

Examples:

Polars::Series.new([1, nil, 2]).str.join("-")
# =>
# shape: (1,)
# Series: '' [str]
# [
#         "1-2"
# ]
Polars::Series.new([1, nil, 2]).str.join("-", ignore_nulls: false)
# =>
# shape: (1,)
# Series: '' [str]
# [
#         null
# ]

Parameters:

  • delimiter (String) (defaults to: "-") —

    The delimiter to insert between consecutive string values.

Returns:



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# File 'lib/polars/string_name_space.rb', line 252

def join(delimiter = "-", ignore_nulls: true)
  super
end

#json_path_match(json_path) ⇒ Series

Extract the first match of json string with provided JSONPath expression.

Throw errors if encounter invalid json strings. All return value will be casted to Utf8 regardless of the original value.

Documentation on JSONPath standard can be found here.

Examples:

df = Polars::DataFrame.new(
  {"json_val" => ['{"a":"1"}', nil, '{"a":2}', '{"a":2.1}', '{"a":true}']}
)
df.select(Polars.col("json_val").str.json_path_match("$.a"))[0.., 0]
# =>
# shape: (5,)
# Series: 'json_val' [str]
# [
#         "1"
#         null
#         "2"
#         "2.1"
#         "true"
# ]

Parameters:

  • json_path (String) —

    A valid JSON path query string.

Returns:



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# File 'lib/polars/string_name_space.rb', line 415

def json_path_match(json_path)
  super
end

#lengths ⇒ Series

Note:

The returned lengths are equal to the number of bytes in the UTF8 string. If you need the length in terms of the number of characters, use n_chars instead.

Get length of the string values in the Series (as number of bytes).

Examples:

s = Polars::Series.new(["Café", nil, "345", "東京"])
s.str.lengths
# =>
# shape: (4,)
# Series: '' [u32]
# [
#         5
#         null
#         3
#         6
# ]

Returns:



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# File 'lib/polars/string_name_space.rb', line 200

def lengths
  super
end

#ljust(width, fillchar = " ") ⇒ Series

Return the string left justified in a string of length width.

Padding is done using the specified fillchar. The original string is returned if width is less than or equal to s.length.

Examples:

s = Polars::Series.new("a", ["cow", "monkey", nil, "hippopotamus"])
s.str.ljust(8, "*")
# =>
# shape: (4,)
# Series: 'a' [str]
# [
#         "cow*****"
#         "monkey**"
#         null
#         "hippopotamus"
# ]

Parameters:

  • width (Integer) —

    Justify left to this length.

  • fillchar (String) (defaults to: " ") —

    Fill with this ASCII character.

Returns:



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# File 'lib/polars/string_name_space.rb', line 726

def ljust(width, fillchar = " ")
  super
end

#lstrip(matches = nil) ⇒ Series

Remove leading whitespace.

Parameters:

  • matches (String, nil) (defaults to: nil) —

    An optional single character that should be trimmed

Returns:



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# File 'lib/polars/string_name_space.rb', line 671

def lstrip(matches = nil)
  super
end

#n_chars ⇒ Series

Note:

If you know that you are working with ASCII text, lengths will be equivalent, and faster (returns length in terms of the number of bytes).

Get length of the string values in the Series (as number of chars).

Examples:

s = Polars::Series.new(["Café", nil, "345", "東京"])
s.str.n_chars
# =>
# shape: (4,)
# Series: '' [u32]
# [
#         4
#         null
#         3
#         2
# ]

Returns:



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# File 'lib/polars/string_name_space.rb', line 224

def n_chars
  super
end

#replace(pattern, value, literal: false) ⇒ Series

Replace first matching regex/literal substring with a new string value.

Examples:

s = Polars::Series.new(["123abc", "abc456"])
s.str.replace('abc\b', "ABC")
# =>
# shape: (2,)
# Series: '' [str]
# [
#         "123ABC"
#         "abc456"
# ]

Parameters:

  • pattern (String) —

    A valid regex pattern.

  • value (String) —

    Substring to replace.

  • literal (Boolean) (defaults to: false) —

    Treat pattern as a literal string.

Returns:



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# File 'lib/polars/string_name_space.rb', line 626

def replace(pattern, value, literal: false)
  super
end

#replace_all(pattern, value, literal: false) ⇒ Series

Replace all matching regex/literal substrings with a new string value.

Examples:

df = Polars::Series.new(["abcabc", "123a123"])
df.str.replace_all("a", "-")
# =>
# shape: (2,)
# Series: '' [str]
# [
#         "-bc-bc"
#         "123-123"
# ]

Parameters:

  • pattern (String) —

    A valid regex pattern.

  • value (String) —

    Substring to replace.

  • literal (Boolean) (defaults to: false) —

    Treat pattern as a literal string.

Returns:



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# File 'lib/polars/string_name_space.rb', line 651

def replace_all(pattern, value, literal: false)
  super
end

#rjust(width, fillchar = " ") ⇒ Series

Return the string right justified in a string of length width.

Padding is done using the specified fillchar. The original string is returned if width is less than or equal to s.length.

Examples:

s = Polars::Series.new("a", ["cow", "monkey", nil, "hippopotamus"])
s.str.rjust(8, "*")
# =>
# shape: (4,)
# Series: 'a' [str]
# [
#         "*****cow"
#         "**monkey"
#         null
#         "hippopotamus"
# ]

Parameters:

  • width (Integer) —

    Justify right to this length.

  • fillchar (String) (defaults to: " ") —

    Fill with this ASCII character.

Returns:



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# File 'lib/polars/string_name_space.rb', line 754

def rjust(width, fillchar = " ")
  super
end

#rstrip(matches = nil) ⇒ Series

Remove trailing whitespace.

Parameters:

  • matches (String, nil) (defaults to: nil) —

    An optional single character that should be trimmed

Returns:



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# File 'lib/polars/string_name_space.rb', line 681

def rstrip(matches = nil)
  super
end

#slice(offset, length = nil) ⇒ Series

Create subslices of the string values of a Utf8 Series.

Examples:

s = Polars::Series.new("s", ["pear", nil, "papaya", "dragonfruit"])
s.str.slice(-3)
# =>
# shape: (4,)
# Series: 's' [str]
# [
#         "ear"
#         null
#         "aya"
#         "uit"
# ]

Using the optional length parameter

s.str.slice(4, 3)
# =>
# shape: (4,)
# Series: 's' [str]
# [
#         ""
#         null
#         "ya"
#         "onf"
# ]

Parameters:

  • offset (Integer) —

    Start index. Negative indexing is supported.

  • length (Integer) (defaults to: nil) —

    Length of the slice. If set to nil (default), the slice is taken to the end of the string.

Returns:



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# File 'lib/polars/string_name_space.rb', line 806

def slice(offset, length = nil)
  s = Utils.wrap_s(_s)
  s.to_frame.select(Polars.col(s.name).str.slice(offset, length)).to_series
end

#split(by, inclusive: false) ⇒ Series

Split the string by a substring.

Parameters:

  • by (String) —

    Substring to split by.

  • inclusive (Boolean) (defaults to: false) —

    If true, include the split character/string in the results.

Returns:



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# File 'lib/polars/string_name_space.rb', line 500

def split(by, inclusive: false)
  super
end

#split_exact(by, n, inclusive: false) ⇒ Series

Split the string by a substring using n splits.

Results in a struct of n+1 fields.

If it cannot make n splits, the remaining field elements will be null.

Examples:

df = Polars::DataFrame.new({"x" => ["a_1", nil, "c", "d_4"]})
df["x"].str.split_exact("_", 1).alias("fields")
# =>
# shape: (4,)
# Series: 'fields' [struct[2]]
# [
#         {"a","1"}
#         {null,null}
#         {"c",null}
#         {"d","4"}
# ]

Split string values in column x in exactly 2 parts and assign each part to a new column.

df["x"]
  .str.split_exact("_", 1)
  .struct.rename_fields(["first_part", "second_part"])
  .alias("fields")
  .to_frame
  .unnest("fields")
# =>
# shape: (4, 2)
# ┌────────────┬─────────────┐
# │ first_part ┆ second_part │
# │ ---        ┆ ---         │
# │ str        ┆ str         │
# ╞════════════╪═════════════╡
# │ a          ┆ 1           │
# │ null       ┆ null        │
# │ c          ┆ null        │
# │ d          ┆ 4           │
# └────────────┴─────────────┘

Parameters:

  • by (String) —

    Substring to split by.

  • n (Integer) —

    Number of splits to make.

  • inclusive (Boolean) (defaults to: false) —

    If true, include the split character/string in the results.

Returns:



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# File 'lib/polars/string_name_space.rb', line 551

def split_exact(by, n, inclusive: false)
  super
end

#splitn(by, n) ⇒ Series

Split the string by a substring, restricted to returning at most n items.

If the number of possible splits is less than n-1, the remaining field elements will be null. If the number of possible splits is n-1 or greater, the last (nth) substring will contain the remainder of the string.

Examples:

df = Polars::DataFrame.new({"s" => ["foo bar", nil, "foo-bar", "foo bar baz"]})
df["s"].str.splitn(" ", 2).alias("fields")
# =>
# shape: (4,)
# Series: 'fields' [struct[2]]
# [
#         {"foo","bar"}
#         {null,null}
#         {"foo-bar",null}
#         {"foo","bar baz"}
# ]

Split string values in column s in exactly 2 parts and assign each part to a new column.

df["s"]
  .str.splitn(" ", 2)
  .struct.rename_fields(["first_part", "second_part"])
  .alias("fields")
  .to_frame
  .unnest("fields")
# =>
# shape: (4, 2)
# ┌────────────┬─────────────┐
# │ first_part ┆ second_part │
# │ ---        ┆ ---         │
# │ str        ┆ str         │
# ╞════════════╪═════════════╡
# │ foo        ┆ bar         │
# │ null       ┆ null        │
# │ foo-bar    ┆ null        │
# │ foo        ┆ bar baz     │
# └────────────┴─────────────┘

Parameters:

  • by (String) —

    Substring to split by.

  • n (Integer) —

    Max number of items to return.

Returns:



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# File 'lib/polars/string_name_space.rb', line 600

def splitn(by, n)
  s = Utils.wrap_s(_s)
  s.to_frame.select(Polars.col(s.name).str.splitn(by, n)).to_series
end

#starts_with(sub) ⇒ Series

Check if string values start with a substring.

Examples:

s = Polars::Series.new("fruits", ["apple", "mango", nil])
s.str.starts_with("app")
# =>
# shape: (3,)
# Series: 'fruits' [bool]
# [
#         true
#         false
#         null
# ]

Parameters:

  • sub (String) —

    Prefix substring.

Returns:



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# File 'lib/polars/string_name_space.rb', line 334

def starts_with(sub)
  super
end

#strip(matches = nil) ⇒ Series

Remove leading and trailing whitespace.

Parameters:

  • matches (String, nil) (defaults to: nil) —

    An optional single character that should be trimmed

Returns:



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# File 'lib/polars/string_name_space.rb', line 661

def strip(matches = nil)
  super
end

#strptime(datatype, fmt = nil, strict: true, exact: true, cache: true) ⇒ Series

Parse a Series of dtype Utf8 to a Date/Datetime Series.

Examples:

Dealing with a consistent format:

s = Polars::Series.new(["2020-01-01 01:00Z", "2020-01-01 02:00Z"])
s.str.strptime(Polars::Datetime, "%Y-%m-%d %H:%M%#z")
# =>
# shape: (2,)
# Series: '' [datetime[μs, UTC]]
# [
#         2020-01-01 01:00:00 UTC
#         2020-01-01 02:00:00 UTC
# ]

Dealing with different formats.

s = Polars::Series.new(
  "date",
  [
    "2021-04-22",
    "2022-01-04 00:00:00",
    "01/31/22",
    "Sun Jul  8 00:34:60 2001"
  ]
)
s.to_frame.select(
  Polars.coalesce(
    Polars.col("date").str.strptime(Polars::Date, "%F", strict: false),
    Polars.col("date").str.strptime(Polars::Date, "%F %T", strict: false),
    Polars.col("date").str.strptime(Polars::Date, "%D", strict: false),
    Polars.col("date").str.strptime(Polars::Date, "%c", strict: false)
  )
).to_series
# =>
# shape: (4,)
# Series: 'date' [date]
# [
#         2021-04-22
#         2022-01-04
#         2022-01-31
#         2001-07-08
# ]

Parameters:

  • datatype (Symbol) —

    :date, :dateime, or :time.

  • fmt (String) (defaults to: nil) —

    Format to use, refer to the chrono strftime documentation for specification. Example: "%y-%m-%d".

  • strict (Boolean) (defaults to: true) —

    Raise an error if any conversion fails.

  • exact (Boolean) (defaults to: true) —
    • If true, require an exact format match.
    • If false, allow the format to match anywhere in the target string.
  • cache (Boolean) (defaults to: true) —

    Use a cache of unique, converted dates to apply the datetime conversion.

Returns:



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# File 'lib/polars/string_name_space.rb', line 176

def strptime(datatype, fmt = nil, strict: true, exact: true, cache: true)
  super
end

#to_date(format = nil, strict: true, exact: true, cache: true) ⇒ Series

Convert a Utf8 column into a Date column.

Examples:

s = Polars::Series.new(["2020/01/01", "2020/02/01", "2020/03/01"])
s.str.to_date
# =>
# shape: (3,)
# Series: '' [date]
# [
#         2020-01-01
#         2020-02-01
#         2020-03-01
# ]

Parameters:

  • format (String) (defaults to: nil) —

    Format to use for conversion. Refer to the chrono crate documentation for the full specification. Example: "%Y-%m-%d". If set to nil (default), the format is inferred from the data.

  • strict (Boolean) (defaults to: true) —

    Raise an error if any conversion fails.

  • exact (Boolean) (defaults to: true) —

    Require an exact format match. If false, allow the format to match anywhere in the target string.

  • cache (Boolean) (defaults to: true) —

    Use a cache of unique, converted dates to apply the conversion.

Returns:



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# File 'lib/polars/string_name_space.rb', line 41

def to_date(format = nil, strict: true, exact: true, cache: true)
  super
end

#to_datetime(format = nil, time_unit: nil, time_zone: nil, strict: true, exact: true, cache: true, ambiguous: "raise") ⇒ Series

Convert a Utf8 column into a Datetime column.

Examples:

s = Polars::Series.new(["2020-01-01 01:00Z", "2020-01-01 02:00Z"])
s.str.to_datetime("%Y-%m-%d %H:%M%#z")
# =>
# shape: (2,)
# Series: '' [datetime[μs, UTC]]
# [
#         2020-01-01 01:00:00 UTC
#         2020-01-01 02:00:00 UTC
# ]

Parameters:

  • format (String) (defaults to: nil) —

    Format to use for conversion. Refer to the chrono crate documentation for the full specification. Example: "%Y-%m-%d %H:%M:%S". If set to nil (default), the format is inferred from the data.

  • time_unit ("us", "ns", "ms") (defaults to: nil) —

    Unit of time for the resulting Datetime column. If set to nil (default), the time unit is inferred from the format string if given, eg: "%F %T%.3f" => Datetime("ms"). If no fractional second component is found, the default is "us".

  • time_zone (String) (defaults to: nil) —

    Time zone for the resulting Datetime column.

  • strict (Boolean) (defaults to: true) —

    Raise an error if any conversion fails.

  • exact (Boolean) (defaults to: true) —

    Require an exact format match. If false, allow the format to match anywhere in the target string.

  • cache (Boolean) (defaults to: true) —

    Use a cache of unique, converted datetimes to apply the conversion.

Returns:



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# File 'lib/polars/string_name_space.rb', line 79

def to_datetime(
  format = nil,
  time_unit: nil,
  time_zone: nil,
  strict: true,
  exact: true,
  cache: true,
  ambiguous: "raise"
)
  super
end

#to_lowercase ⇒ Series

Modify the strings to their lowercase equivalent.

Returns:



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# File 'lib/polars/string_name_space.rb', line 761

def to_lowercase
  super
end

#to_time(format = nil, strict: true, cache: true) ⇒ Series

Convert a Utf8 column into a Time column.

Examples:

s = Polars::Series.new(["01:00", "02:00", "03:00"])
s.str.to_time("%H:%M")
# =>
# shape: (3,)
# Series: '' [time]
# [
#         01:00:00
#         02:00:00
#         03:00:00
# ]

Parameters:

  • format (String) (defaults to: nil) —

    Format to use for conversion. Refer to the chrono crate documentation for the full specification. Example: "%H:%M:%S". If set to nil (default), the format is inferred from the data.

  • strict (Boolean) (defaults to: true) —

    Raise an error if any conversion fails.

  • cache (Boolean) (defaults to: true) —

    Use a cache of unique, converted times to apply the conversion.

Returns:



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# File 'lib/polars/string_name_space.rb', line 116

def to_time(format = nil, strict: true, cache: true)
  super
end

#to_uppercase ⇒ Series

Modify the strings to their uppercase equivalent.

Returns:



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# File 'lib/polars/string_name_space.rb', line 768

def to_uppercase
  super
end

#zfill(length) ⇒ Series

Fills the string with zeroes.

Return a copy of the string left filled with ASCII '0' digits to make a string of length width.

A leading sign prefix ('+'/'-') is handled by inserting the padding after the sign character rather than before. The original string is returned if width is less than or equal to s.length.

Parameters:

  • length (Integer) —

    Fill the value up to this length.

Returns:



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# File 'lib/polars/string_name_space.rb', line 698

def zfill(length)
  super
end