pyspark-json-loader 0.1.6

A package to load and preprocess JSON data using PySpark

PySpark JSON Loader

Overview

pyspark-json-loader is a Python package designed to facilitate loading and preprocessing JSON data using PySpark. It provides functions to start a Spark session, connect to a PostgreSQL database, preprocess data, and convert Spark DataFrames to Pandas DataFrames.

Installation

To install the package, run:

pip install pyspark-json-loader

Usage

Here is a detailed guide on how to use the functions provided by the pyspark-json-loader package.

Importing the Module

To use the functions in this package, you need to import them as follows:

from pyspark_json_loader import (
    load_json_file,
    start_spark_session,
    connect_to_db,
    preprocess_dataframe,
    convert_to_pandas,
    split_and_convert,
    add_lists,
    increment_index,
    index,
    multiply_lists,
    multiplyP_lists,
    sum_list,
    list_to_colon_separated_string
)

Functions

1. load_json_file(file_name)

Description: This function loads a JSON file and returns its contents as a Python dictionary.

Parameters:

• file_name (str): The path to the JSON file.

Returns:

• dict: The contents of the JSON file.

Example:

json_data = load_json_file('data.json')
print(json_data)

Output:

{
    "column1": "value1",
    "column2": "value2"
}

2. start_spark_session()

Description: This function starts a Spark session with the specified JAR file.

Returns:

• SparkSession: The Spark session object.

Example:

spark = start_spark_session()
print(spark)

Output:

<pyspark.sql.session.SparkSession object at 0x...>

3. connect_to_db(spark, host_name, port_number, db_name, user, password, query, null_value=0)

Description: This function connects to a PostgreSQL database using the provided connection details and query.

Parameters:

• spark (SparkSession): The Spark session object.
• host_name (str): The hostname of the PostgreSQL server.
• port_number (int): The port number of the PostgreSQL server.
• db_name (str): The name of the database.
• user (str): The username for the database.
• password (str): The password for the database.
• query (str): The SQL query to execute.
• null_value (int, optional): The value to use for null values. Default is 0.

Returns:

• DataFrame: The resulting DataFrame from the query.

Example:

df = connect_to_db(spark, 'localhost', 5432, 'mydatabase', 'user', 'password', 'SELECT * FROM mytable')
df.show()

Output:

| id | name |
|----|------|
| 1  | John |
| 2  | Jane |

4. preprocess_dataframe(df, json_data)

Description: This function preprocesses a DataFrame by filling null values based on the provided JSON data.

Parameters:

• df (DataFrame): The Spark DataFrame to preprocess.
• json_data (dict): The JSON data to use for preprocessing.

Returns:

• DataFrame: The preprocessed DataFrame.

Example:

preprocessed_df = preprocess_dataframe(df, json_data)
preprocessed_df.show()

Output:

+---+------+
| id|  name|
+---+------+
|  1|  John|
|  2|  Jane|
+---+------+

5. convert_to_pandas(grouped_metrics_df)

Description: This function converts a Spark DataFrame to a Pandas DataFrame and adds a UUID column.

Parameters:

• grouped_metrics_df (DataFrame): The Spark DataFrame to convert.

Returns:

• DataFrame: The resulting Pandas DataFrame.

Example:

pandas_df = convert_to_pandas(preprocessed_df)
print(pandas_df)

Output:

   id   name                               Id
0   1   John  0a539f3c... (UUID)
1   2   Jane  1d2e4f5a... (UUID)

6. split_and_convert(vector_string)

Description: This function splits a colon-separated string and converts each part to an integer, handling edge cases.

Parameters:

• vector_string (str): The colon-separated string to split and convert.

Returns:

• list: The list of integers.

Example:

result = split_and_convert("1:2:3")
print(result)

Output:

[1, 2, 3]

7. add_lists(row)

Description: This function adds corresponding elements of lists contained in a row, handling different lengths.

Parameters:

• row (list of lists): The lists to add.

Returns:

• list: The resulting list after addition.

Example:

result = add_lists([[1, 2, 3], [4, 5, 6]])
print(result)

Output:

[5, 7, 9]

8. increment_index(row)

Description: This function creates a list of incremental integers starting from 1, with the same length as the input list.

Parameters:

• row (list): The input list.

Returns:

• list: The list of incremental integers.

Example:

result = increment_index([10, 20, 30])
print(result)

Output:

[1, 2, 3]

9. index(row)

Description: This function creates a list of incremental integers starting from 0, with the same length as the input list.

Parameters:

• row (list): The input list.

Returns:

• list: The list of incremental integers.

Example:

result = index([10, 20, 30])
print(result)

Output:

[0, 1, 2]

10. multiply_lists(row1, row2)

Description: This function multiplies corresponding elements of two lists and doubles the result.

Parameters:

• row1 (list): The first list of numbers.
• row2 (list): The second list of numbers.

Returns:

• list: The list of multiplied and doubled results.

Example:

result = multiply_lists([1, 2, 3], [4, 5, 6])
print(result)

Output:

[8, 20, 36]

11. multiplyP_lists(row1, row2)

Description: This function multiplies corresponding elements of two lists.

Parameters:

• row1 (list): The first list of numbers.
• row2 (list): The second list of numbers.

Returns:

• list: The list of multiplied results.

Example:

result = multiplyP_lists([1, 2, 3], [4, 5, 6])
print(result)

Output:

[4, 10, 18]

12. sum_list(row)

Description: This function calculates the sum of elements in a list.

Parameters:

• row (list): The input list.

Returns:

• int: The sum of the list elements.

Example:

result = sum_list([1, 2, 3])
print(result)

Output:

6

13. list_to_colon_separated_string(lst)

Description: This function converts a list of numbers to a colon-separated string.

Parameters:

• lst (list): The list of numbers.

Returns:

• str: The colon-separated string.

Example:

result = list_to_colon_separated_string([1, 2, 3])
print(result)

Output:

"1:2:3"