How can I capitalize each word delimited by some characters in Pyspark?

Question

I'm currently working with Pyspark and I'm facing a seemingly simple problem.

I want to capitalize the first letter of each word, even if the words are separated by characters in the following list:

delimiter_list = [' ', '(', '+', '/', '-']

Actually, initcap works only for words delimited by blank types.

Is there an efficient solution? Here are some input-output examples:

input	output
baden-baden	Baden-Baden
markranstadt/brandenburg-kirchmöser	Markranstadt/Brandenburg-Kirchmöser
ostrow mazowiecki/bialystok	Ostrow Mazowiecki/Bialystok

Answer 1

As the delimiter isn't the same, you can first add a common delimiter, say # after each character in your list delimiter_list using regexp_replace:

regexp_replace(words, '(\\s|\\(|\\+|-|\\/)(.)', '$1#$2')

Now, you can split by # and transform the resulting array by capitalizing each element using transform function. Finally, join the array elements to get the original string using array_join function:

from pyspark.sql import functions as F

df1 = df.withColumn(
    "words_capitalized",
    F.expr(r"""
        array_join(
            transform(
                split(regexp_replace(words, '(\\s|\\(|\\+|-|\\/)(.)', '$1#$2'), '#'),
                x -> initcap(x)
            ),
            ""
        )
    """)
)

df1.show(truncate=False)

#+-----------------------------------+-----------------------------------+
#|words                              |words_capitalized                  |
#+-----------------------------------+-----------------------------------+
#|baden-baden                        |Baden-Baden                        |
#|markranstadt/brandenburg-kirchmöser|Markranstadt/Brandenburg-Kirchmöser|
#|ostrow mazowiecki/bialystok        |Ostrow Mazowiecki/Bialystok        |
#+-----------------------------------+-----------------------------------+