Calling Functions and Stored Procedures in Snowpark Python¶

Calling System-Defined Functions¶

If you need to call system-defined SQL functions, use the equivalent functions in the snowflake.snowpark.functions module.

The following example calls the upper function in the functions module (the equivalent of the system-defined UPPER function) to return the values in the name column of the sample_product_data table with the letters in uppercase:

# Import the upper function from the functions module.
from snowflake.snowpark.functions import upper, col
session.table("sample_product_data").select(upper(col("name")).alias("upper_name")).collect()

[Row(UPPER_NAME='PRODUCT 1'), Row(UPPER_NAME='PRODUCT 1A'), Row(UPPER_NAME='PRODUCT 1B'), Row(UPPER_NAME='PRODUCT 2'),
Row(UPPER_NAME='PRODUCT 2A'), Row(UPPER_NAME='PRODUCT 2B'), Row(UPPER_NAME='PRODUCT 3'), Row(UPPER_NAME='PRODUCT 3A'),
Row(UPPER_NAME='PRODUCT 3B'), Row(UPPER_NAME='PRODUCT 4'), Row(UPPER_NAME='PRODUCT 4A'), Row(UPPER_NAME='PRODUCT 4B')]

If a system-defined SQL function is not available in the functions module, you can use one of the following approaches:

• Use the call_function function to call the system-defined function.

• Use the function function to create a function object that you can use to call the system-defined function.

call_function and function are defined in the snowflake.snowpark.functions module.

For call_function, pass the name of the system-defined function as the first argument. If you need to pass the values of columns to the system-defined function, define and pass Column objects as additional arguments to the call_function function.

The following example calls the system-defined function RADIANS, passing in the value from the column col1:

# Import the call_function function from the functions module.
from snowflake.snowpark.functions import call_function
df = session.create_dataframe([[1, 2], [3, 4]], schema=["col1", "col2"])
# Call the system-defined function RADIANS() on col1.
df.select(call_function("radians", col("col1"))).collect()

[Row(RADIANS("COL1")=0.017453292519943295), Row(RADIANS("COL1")=0.05235987755982988)]

The call_function function returns a Column, which you can pass to the DataFrame transformation methods (e.g. filter, select, etc.).

For function, pass the name of the system-defined function, and use the returned function object to call the system-defined function. For example:

# Import the call_function function from the functions module.
from snowflake.snowpark.functions import function

# Create a function object for the system-defined function RADIANS().
radians = function("radians")
df = session.create_dataframe([[1, 2], [3, 4]], schema=["col1", "col2"])
# Call the system-defined function RADIANS() on col1.
df.select(radians(col("col1"))).collect()

[Row(RADIANS("COL1")=0.017453292519943295), Row(RADIANS("COL1")=0.05235987755982988)]

Calling User-Defined Functions (UDFs)¶

To call UDFs that you registered by name and UDFs that you created by executing CREATE FUNCTION, use the call_udf function in the snowflake.snowpark.functions module. Pass the name of the UDF as the first argument and any UDF parameters as additional arguments.

The following example calls the UDF function minus_one, passing in the values from the columns col1 and col2. The example passes the return value from minus_one to the select method of the DataFrame.

# Import the call_udf function from the functions module.
from snowflake.snowpark.functions import call_udf

# Runs the scalar function 'minus_one' on col1 of df.
df = session.create_dataframe([[1, 2], [3, 4]], schema=["col1", "col2"])
df.select(call_udf("minus_one", col("col1"))).collect()

[Row(MINUS_ONE("COL1")=0), Row(MINUS_ONE("COL1")=2)]

Calling User-Defined Table Functions (UDTFs)¶

To call UDTFs that you registered by name and UDTFs that you created by executing CREATE FUNCTION, use one of the functions listed below. Both return a DataFrame representing a lazily-evaluated relational dataset.

Note that you can use these to also call other table functions, including the system-defined table functions.

For more information on registering a UDTF, see Registering a UDTF.

• To call the UDTF without specifying a lateral join, call the table_function function in the snowflake.snowpark.Session class.

  For the function reference and examples, see Session.table_function.

  Code in the following example uses table_function to call the generator_udtf function registered with the udtf function.

  from snowflake.snowpark.types import IntegerType, StructField, StructType
  from snowflake.snowpark.functions import udtf, lit
  class GeneratorUDTF:
      def process(self, n):
          for i in range(n):
              yield (i, )
  generator_udtf = udtf(GeneratorUDTF, output_schema=StructType([StructField("number", IntegerType())]), input_types=[IntegerType()])
  session.table_function(generator_udtf(lit(3))).collect()
  

  Copy

  [Row(NUMBER=0), Row(NUMBER=1), Row(NUMBER=2)]
  

• To make a call to the UDTF in which your call specifies a lateral join, use the join_table_function function in the snowflake.snowpark.DataFrame class.

  When you lateral join a UDTF, you can specify the PARTITION BY and ORDER BY clauses.

  For the function reference and examples, see DataFrame.join_table_function.

  Code in the following example performs a lateral join, specifying the partition_by and order_by parameters. Code in this example first calls the snowflake.snowpark.functions.table_function function to create a function object representing the system-defined SPLIT_TO_TABLE function. It is this function object that join_table_function then calls.

  For the snowflake.snowpark.functions.table_function function reference, see table_function. For the SPLIT_TO_TABLE function reference, see SPLIT_TO_TABLE.

  from snowflake.snowpark.functions import table_function
  split_to_table = table_function("split_to_table")
  df = session.create_dataframe([
      ["John", "James", "address1 address2 address3"],
      ["Mike", "James", "address4 address5 address6"],
      ["Cathy", "Stone", "address4 address5 address6"],
  ],
  schema=["first_name", "last_name", "addresses"])
  df.join_table_function(split_to_table(df["addresses"], lit(" ")).over(partition_by="last_name", order_by="first_name")).show()
  

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  ----------------------------------------------------------------------------------------
  |"FIRST_NAME"  |"LAST_NAME"  |"ADDRESSES"                 |"SEQ"  |"INDEX"  |"VALUE"   |
  ----------------------------------------------------------------------------------------
  |John          |James        |address1 address2 address3  |1      |1        |address1  |
  |John          |James        |address1 address2 address3  |1      |2        |address2  |
  |John          |James        |address1 address2 address3  |1      |3        |address3  |
  |Mike          |James        |address4 address5 address6  |2      |1        |address4  |
  |Mike          |James        |address4 address5 address6  |2      |2        |address5  |
  |Mike          |James        |address4 address5 address6  |2      |3        |address6  |
  |Cathy         |Stone        |address4 address5 address6  |3      |1        |address4  |
  |Cathy         |Stone        |address4 address5 address6  |3      |2        |address5  |
  |Cathy         |Stone        |address4 address5 address6  |3      |3        |address6  |
  ----------------------------------------------------------------------------------------
  

Calling Stored Procedures¶

To call a stored procedure, use the call method of the Session class.

session.call("your_proc_name", 1)

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