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regeximpala

Regex for extracting part of a file path

I am using regex function in Impala to find the folder name in file path but it doesn't seem to give me correct result

I want to parse out "one" from this file path:

/this/one/path/to/hdfs

This is the regex which I used:

regexp_extract(filepath,'[/]+',0)
Solution

  • If here we wish to capture the /, then we might just want to try ([\/]+). There should be other expressions to extract one also, such as: 

    (?:\/[a-z]+\/)(.+?)(?:\/.+)

    and our code might look like:

    regexp_extract(filepath, '(?:\/[a-z]+\/)(.+?)(?:\/.+)', 2)

    or 

    regexp_extract(filepath, '(?:\/.+?\/)(.+?)(?:\/.+)', 2)

    Compartments

    In this case, we are not capturing what is behind one using a non-capturing group:

    (?:\/[a-z]+\/)

    then we capture one using:

    (.+?)

    and finally we add a right boundary after one in another non-capturing group:

    (?:\/.+)

    RegEx Circuit

    jex.im visualizes regular expressions:

    enter image description here

    DEMO

    Depending on which slash, one might be located, we can modify our expression. For example, in this case, this expression also might be working:

    (?:\/.+?\/)(.+?)(?:\/.+)

    DEMO