CODEWITHSUNDEEP
pythonregexapache-sparkpysparkapache-spark-sql
haimen
haimen

Reputation: 2015

Filter rows in Spark dataframe from the words in RDD

I have the following commands in spark,

data = sqlContext.sql("select column1, column2, column3 from table_name")

words = sc.textFile("words.txt")

words.txt has a bunch of words and data has three string columns taken from table_name.

Now I want to filter out rows in data (spark dataframe) whenever the word pattern of each word from words.txt occurs in any of the three columns of data.

For example if words.txt has word such as gon and if any of the three columns of data contains values as bygone, gone etc, I want to filter out that row.

I've tried the following:

data.filter(~data['column1'].like('%gon%') | data['column2'].like('%gon%') | data['column3'].like('%gon%')).toPandas()

This works for one word. But I want to check all the words from the words.txt and remove it. Is there a way to do this?

I am new to PySpark. Any suggestions would be helpful.

Upvotes: 5

Views: 3541

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627100

You may read the words from the words.txt, and build a regex pattern like this:

(?s)^(?=.*word1)(?=.*word2)(?=.*word3)

etc. where (?s) allows . to match any symbol, ^ matches the string start position and then each (?=...) lookahead requires the presence of each word in the string.

So, if you place the regex into a rx var, it will look like:

data.filter(~data['column1'].rlike(rx) | data['column2'].rlike(rx) | data['column3'].rlike(rx)).toPandas()

where the regex pattern is passed to rlike method that is similar to like but performs a search based on a regex expression.

Upvotes: 4

Related Questions