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Quinn

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Pyspark helper methods to maximize developer productivity.

Quinn provides DataFrame validation functions, useful column functions / DataFrame transformations, and performant helper functions.

quinn

Documentation

You can find official documentation here.

Setup

Quinn is uploaded to PyPi and can be installed with this command:

pip install quinn

Quinn Helper Functions

import quinn

DataFrame Validations

validate_presence_of_columns()

Raises an exception unless source_df contains the name, age, and fun column.

quinn.validate_presence_of_columns(source_df, ["name", "age", "fun"])

validate_schema()

Raises an exception unless source_df contains all the StructFields defined in the required_schema.

quinn.validate_schema(source_df, required_schema)

validate_absence_of_columns()

Raises an exception if source_df contains age or cool columns.

quinn.validate_absence_of_columns(source_df, ["age", "cool"])

Functions

single_space()

Replaces all multispaces with single spaces (e.g. changes "this has some" to "this has some".

actual_df = source_df.withColumn(
    "words_single_spaced",
    quinn.single_space(col("words"))
)

remove_all_whitespace()

Removes all whitespace in a string (e.g. changes "this has some" to "thishassome".

actual_df = source_df.withColumn(
    "words_without_whitespace",
    quinn.remove_all_whitespace(col("words"))
)

anti_trim()

Removes all inner whitespace, but doesn't delete leading or trailing whitespace (e.g. changes " this has some " to " thishassome ".

actual_df = source_df.withColumn(
    "words_anti_trimmed",
    quinn.anti_trim(col("words"))
)

remove_non_word_characters()

Removes all non-word characters from a string (e.g. changes "si%$#@!#$!@#mpsons" to "simpsons".

actual_df = source_df.withColumn(
    "words_without_nonword_chars",
    quinn.remove_non_word_characters(col("words"))
)

multi_equals()

multi_equals returns true if s1 and s2 are both equal to "cat".

source_df.withColumn(
    "are_s1_and_s2_cat",
    quinn.multi_equals("cat")(col("s1"), col("s2"))
)

approx_equal()

This function takes 3 arguments which are 2 Pyspark DataFrames and one integer values as threshold, and returns the Boolean column which tells if the columns are equal in the threshold.

let the columns be
col1 = [1.2, 2.5, 3.1, 4.0, 5.5]
col2 = [1.3, 2.3, 3.0, 3.9, 5.6]
threshold = 0.2

result = approx_equal(col("col1"), col("col2"), threshold)
result.show()

+-----+
|value|
+-----+
| true|
|false|
| true|
| true|
| true|
+-----+

array_choice()

This function takes a Column as a parameter and returns a PySpark column that contains a random value from the input column parameter

df = spark.createDataFrame([(1,), (2,), (3,), (4,), (5,)], ["values"])
result = df.select(array_choice(col("values")))

The output is :=
+--------------+
|array_choice()|
+--------------+
|             2|
+--------------+

regexp_extract_all()

The regexp_extract_all takes 2 parameters String s and regexp which is a regular expression. This function finds all the matches for the string which satisfies the regular expression.

print(regexp_extract_all("this is a example text message for testing application",r"\b\w*a\w*\b"))

The output is :=
['a', 'example', 'message', 'application']

Where r"\b\w*a\w*\b" pattern checks for words containing letter a

week_start_date()

It takes 2 parameters, column and week_start_day. It returns a Spark Dataframe column which contains the start date of the week. By default the week_start_day is set to "Sun".

For input ["2023-03-05", "2023-03-06", "2023-03-07", "2023-03-08"] the Output is

result = df.select("date", week_start_date(col("date"), "Sun"))
result.show()
+----------+----------------+
|      date|week_start_date |
+----------+----------------+
|2023-03-05|      2023-03-05|
|2023-03-07|      2023-03-05|
|2023-03-08|      2023-03-05|
+----------+----------------+

week_end_date()

It also takes 2 Paramters as Column and week_end_day, and returns the dateframe column which contains the end date of the week. By default the week_end_day is set to "sat"

+---------+-------------+
      date|week_end_date|
+---------+-------------+
2023-03-05|   2023-03-05|
2023-03-07|   2023-03-12|
2023-03-08|   2023-03-12|
+---------+-------------+

uuid5()

This function generates UUIDv5 in string form from the passed column and optionally namespace and optional extra salt. By default namespace is NAMESPACE_DNS UUID and no extra string used to reduce hash collisions.


df = spark.createDataFrame([("lorem",), ("ipsum",)], ["values"])
result = df.select(quinn.uuid5(F.col("values")).alias("uuid5"))
result.show(truncate=False)

The output is :=
+------------------------------------+
|uuid5                               |
+------------------------------------+
|35482fda-c10a-5076-8da2-dc7bf22d6be4|
|51b79c1d-d06c-5b30-a5c6-1fadcd3b2103|
+------------------------------------+

Transformations

snake_case_col_names()

Converts all the column names in a DataFrame to snake_case. It's annoying to write SQL queries when columns aren't snake cased.

quinn.snake_case_col_names(source_df)

sort_columns()

Sorts the DataFrame columns in alphabetical order, including nested columns if sort_nested is set to True. Wide DataFrames are easier to navigate when they're sorted alphabetically.

quinn.sort_columns(df=source_df, sort_order="asc", sort_nested=True)

DataFrame Helpers

with_columns_renamed()

Rename ALL or MULTIPLE columns in a dataframe by implementing a common logic to rename the columns.

Consider you have the following two dataframes for orders coming from a source A and a source B:

order_a_df.show()

+--------+---------+--------+
|order_id|order_qty|store_id|
+--------+---------+--------+
|     001|       23|    45AB|
|     045|        2|    98HX|
|     021|      142|    09AA|
+--------+---------+--------+

order_b_df.show()

+--------+---------+--------+
|order_id|order_qty|store_id|
+--------+---------+--------+
|     001|       23|    47AB|
|     985|        2|    54XX|
|    0112|       12|    09AA|
+--------+---------+--------+

Now, you need to join these two dataframes. However, in Spark, when two dfs with identical column names are joined, you may start running into ambiguous column name issue due to multiple columns with the same name in the resulting df. So it's a best practice to rename all of these columns to reflect which df they originate from:

def add_suffix(s):
    return s + '_a'

order_a_df_renamed = quinn.with_columns_renamed(add_suffix)(order_a_df)

order_a_df_renamed.show()

+----------+-----------+----------+
|order_id_a|order_qty_a|store_id_a|
+----------+-----------+----------+
|       001|         23|      45AB|
|       045|          2|      98HX|
|       021|        142|      09AA|
+----------+-----------+----------+

column_to_list()

Converts a column in a DataFrame to a list of values.

quinn.column_to_list(source_df, "name")

two_columns_to_dictionary()

Converts two columns of a DataFrame into a dictionary. In this example, name is the key and age is the value.

quinn.two_columns_to_dictionary(source_df, "name", "age")

to_list_of_dictionaries()

Converts an entire DataFrame into a list of dictionaries.

quinn.to_list_of_dictionaries(source_df)

show_output_to_df()

quinn.show_output_to_df(output_str, spark)

Parses a spark DataFrame output string into a spark DataFrame. Useful for quickly pulling data from a log into a DataFrame. In this example, output_str is a string of the form:

+----+---+-----------+------+
|name|age|     stuff1|stuff2|
+----+---+-----------+------+
|jose|  1|nice person|  yoyo|
|  li|  2|nice person|  yoyo|
| liz|  3|nice person|  yoyo|
+----+---+-----------+------+

Schema Helpers

schema_from_csv()

Converts a CSV file into a PySpark schema (aka StructType). The CSV must contain the column name and type. The nullable and metadata columns are optional.

quinn.schema_from_csv("schema.csv")

Here's an example CSV file:

name,type
person,string
address,string
phoneNumber,string
age,int

Here's how to convert that CSV file to a PySpark schema using schema_from_csv():

schema = schema_from_csv(spark, "some_file.csv")

StructType([
    StructField("person", StringType(), True),
    StructField("address", StringType(), True),
    StructField("phoneNumber", StringType(), True),
    StructField("age", IntegerType(), True),
])

Here's a more complex CSV file:

name,type,nullable,metadata
person,string,false,{"description":"The person's name"}
address,string
phoneNumber,string,TRUE,{"description":"The person's phone number"}
age,int,False

Here's how to read this CSV file into a PySpark schema:

another_schema = schema_from_csv(spark, "some_file.csv")

StructType([
    StructField("person", StringType(), False, {"description": "The person's name"}),
    StructField("address", StringType(), True),
    StructField("phoneNumber", StringType(), True, {"description": "The person's phone number"}),
    StructField("age", IntegerType(), False),
])

print_schema_as_code()

Converts a Spark DataType to a string of Python code that can be evaluated as code using eval(). If the DataType is a StructType, this can be used to print an existing schema in a format that can be copy-pasted into a Python script, log to a file, etc.

For example:

# Consider the below schema for fields
fields = [
    StructField("simple_int", IntegerType()),
    StructField("decimal_with_nums", DecimalType(19, 8)),
    StructField("array", ArrayType(FloatType()))
]
schema = StructType(fields)

printable_schema: str = quinn.print_schema_as_code(schema)
print(printable_schema)

StructType(
	fields=[
		StructField("simple_int", IntegerType(), True),
		StructField("decimal_with_nums", DecimalType(19, 8), True),
		StructField(
			"array",
			ArrayType(FloatType()),
			True,
		),
	]
)

Once evaluated, the printable schema is a valid schema that can be used in dataframe creation, validation, etc.

from chispa.schema_comparer import assert_basic_schema_equality

parsed_schema = eval(printable_schema)
assert_basic_schema_equality(parsed_schema, schema) # passes

print_schema_as_code() can also be used to print other DataType objects.

ArrayType

array_type = ArrayType(FloatType())
printable_type: str = quinn.print_schema_as_code(array_type)
print(printable_type)

ArrayType(FloatType())

MapType

map_type = MapType(StringType(), FloatType())
printable_type: str = quinn.print_schema_as_code(map_type)
print(printable_type)

MapType(
       StringType(),
       FloatType(),
       True,
)

IntegerType, StringType etc.

integer_type = IntegerType()
printable_type: str = quinn.print_schema_as_code(integer_type)
print(printable_type)

IntegerType()

Pyspark Core Class Extensions

import pyspark.sql.functions as F
import quinn

Column Extensions

is_falsy()

Returns a Column indicating whether all values in the Column are False or NULL: True if has_stuff is None or False.

source_df.withColumn("is_stuff_falsy", quinn.is_falsy(F.col("has_stuff")))

is_truthy()

Calculates a boolean expression that is the opposite of is_falsy for the given Column: True unless has_stuff is None or False.

source_df.withColumn("is_stuff_truthy", quinn.is_truthy(F.col("has_stuff")))

is_null_or_blank()

Returns a Boolean value which expresses whether a given column is NULL or contains only blank characters: True if blah is null or blank (the empty string or a string that only contains whitespace).

source_df.withColumn("is_blah_null_or_blank", quinn.is_null_or_blank(F.col("blah")))

is_not_in()

To see if a value is not in a list of values: True if fun_thing is not included in the bobs_hobbies list.

source_df.withColumn("is_not_bobs_hobby", quinn.is_not_in(F.col("fun_thing")))

null_between()

To see if a value is between two values in a null friendly way: True if age is between lower_age and upper_age. If lower_age is populated and upper_age is null, it will return True if age is greater than or equal to lower_age. If lower_age is null and upper_age is populate, it will return True if age is lower than or equal to upper_age.

source_df.withColumn("is_between", quinn.null_between(F.col("age"), F.col("lower_age"), F.col("upper_age")))

Contributing

We are actively looking for feature requests, pull requests, and bug fixes.

Any developer that demonstrates excellence will be invited to be a maintainer of the project.

Code Style

We are using PySpark code-style and sphinx as docstrings format. For more details about sphinx format see this tutorial. A short example of sphinx-formated docstring is placed below:

"""[Summary]

:param [ParamName]: [ParamDescription], defaults to [DefaultParamVal]
:type [ParamName]: [ParamType](, optional)
...
:raises [ErrorType]: [ErrorDescription]
...
:return: [ReturnDescription]
:rtype: [ReturnType]
"""