pyspark.sql.functions.log#

pyspark.sql.functions.log(arg1, arg2=None)[source]#

Returns the first argument-based logarithm of the second argument.

If there is only one argument, then this takes the natural logarithm of the argument.

Added in version 1.5.0.

Changed in version 3.4.0: Supports Spark Connect.

Parameters:

arg1Column, str or float: base number or actual number (in this case base is e). A column that evaluates to a double.
arg2Column, str or float, optional: number to calculate logariphm for. A column that evaluates to a double.

Returns:

Column: logariphm of given value. Returns a column that evaluates to a double.

See also

pyspark.sql.functions.ln()

Examples

Example 1: Specify both base number and the input value

>>> from pyspark.sql import functions as sf
>>> df = spark.sql("SELECT * FROM VALUES (1), (2), (4) AS t(value)")
>>> df.select("*", sf.log(2.0, df.value)).show()
+-----+---------------+
|value|LOG(2.0, value)|
+-----+---------------+
|    1|            0.0|
|    2|            1.0|
|    4|            2.0|
+-----+---------------+

Example 2: Return NULL for invalid input values

>>> from pyspark.sql import functions as sf
>>> df = spark.sql("SELECT * FROM VALUES (1), (2), (0), (-1), (NULL) AS t(value)")
>>> df.select("*", sf.log(3.0, df.value)).show()
+-----+------------------+
|value|   LOG(3.0, value)|
+-----+------------------+
|    1|               0.0|
|    2|0.6309297535714...|
|    0|              NULL|
|   -1|              NULL|
| NULL|              NULL|
+-----+------------------+

Example 3: Specify only the input value (Natural logarithm)

>>> from pyspark.sql import functions as sf
>>> df = spark.sql("SELECT * FROM VALUES (1), (2), (4) AS t(value)")
>>> df.select("*", sf.log(df.value)).show()
+-----+------------------+
|value|         ln(value)|
+-----+------------------+
|    1|               0.0|
|    2|0.6931471805599...|
|    4|1.3862943611198...|
+-----+------------------+