Reference · Strings

lower

lower(str) -> str

What it does

The text in lower case. It knows all of Unicode, so letters outside ASCII are converted too: Greek, Cyrillic and accented letters alike. Digits, punctuation and whitespace stay as they are.

Examples

print(lower("HELLO"))print(lower("ÆRØ 42, OK?"))print(lower("ΑΒΓ"), lower("Straße"))

helloærø 42, ok?αβγ straße

Edge cases

• The empty string gives the empty string.
• The result can be longer than the text: a Turkish dotted İ becomes i with a combining dot, two characters.
• A final Greek sigma lowers to ς, not σ: the rule is positional.
• upper and lower do not always round-trip: upper("ß") is SS, which lowers to ss. For a case-insensitive comparison, lower both sides.

print(lower(""), len(lower("İ")))print(lower("ΣΑΣ"))print(upper("ß") | lower)print(lower("Ab") == lower("aB"))

 2σαςsstrue

Errors

An argument that is not a string is a runtime error, not an error value: lower(42) stops the request. Convert first with str.

print(lower(42))

line 1: `lower` expects a str as argument 1, got int

Chaining

In a pipeline the text comes first, so lower takes it as its only argument:

print("  Mixed Case  " | trim | lower)print(["Ann", "BOB"] | map(lower))print(["img.png", "a.jpg", "b.PNG"] | filter((f) => lower(f) | ends_with(".png")))

mixed case["ann", "bob"]["img.png", "b.PNG"]

See also

upper, trim, str

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