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regex.findall

The regex.findall function returns every non-overlapping match of a regular expression, in the order they appear. Use it to extract identifiers, numbers, or fields from command output and file contents.

Usage​

regex.findall(pattern, text)

Arguments​

pattern

Required. The regular expression, as a string, in RE2 syntax. Inline flags such as (?i) and (?m) work. Lookahead, lookbehind, and backreferences in the pattern are not available.

text
Required. The string to search.

Both arguments are required and can be passed positionally or by keyword.

Returns​

A list of strings, one for each complete match. Capture groups do not change the result: each element is the whole matched text, not the contents of a group. When nothing matches, the result is an empty list.

Examples​

Extract numbers​

output = regex.findall("[0-9]+", "a1 b22 c333")
["1","22","333"]

Capture groups return the whole match​

print(regex.findall("(\\w+)@(\\w+)\\.com", "ann@acme.com bob@corp.com"))
["ann@acme.com", "bob@corp.com"]

To pick out one part of each match, run the pattern again on the matched text, or write a pattern that matches only the part you want.

Read values from a file​

text = fs.read_file("app.yaml")
region = regex.findall("region: (.*)", text)

Here region is ["region: us-east-2"] for a file that contains the line region: us-east-2. Take the part after the colon with split or a second pattern.

No matches​

print(regex.findall("zzz", "abc"))
[]

Errors​

  • A pattern that is not valid RE2 fails with invalid regex: ... followed by the reason.
  • A missing argument, or an argument that is not a string, fails with an argument error.

Related​