Truncate a string with pyspark

Question

I am currently working on PySpark with Databricks and I was looking for a way to truncate a string just like the excel right function does. For example, I would like to change for an ID column in a DataFrame 8841673_3 into 8841673 .

Does anybody knows how I should proceed?

Answer 1

Regular expressions with regexp_extract :

from pyspark.sql.functions import regexp_extract

df = spark.createDataFrame([("8841673_3", )], ("id", ))

df.select(regexp_extract("id", "^(\d+)_.*", 1)).show()
# +--------------------------------+
# |regexp_extract(id, ^(\d+)_.*, 1)|
# +--------------------------------+
# |                         8841673|
# +--------------------------------+

regexp_replace :

from pyspark.sql.functions import regexp_replace

df.select(regexp_replace("id", "_.*$", "")).show()
# +--------------------------+
# |regexp_replace(id, _.*$, )|
# +--------------------------+
# |                   8841673|
# +--------------------------+

or just split :

from pyspark.sql.functions import split

df.select(split("id", "_")[0]).show()
# +---------------+
# |split(id, _)[0]|
# +---------------+
# |        8841673|
# +---------------+

Answer 2

You can use the pyspark.sql.Column.substr method:

import pyspark.sql.functions as F

def left(x, n):
    return x.substr(0, n)

def right(x, n):
    x_len = F.length(x)
    return x.substr(x_len - n, x_len)