Apache Pig - LOG10()

The LOG10() function of Pig Latin is used to calculate the natural logarithm base 10 value of a given expression.

grunt> LOG10(expression)

Example

Assume that there is a file named math.txt in the HDFS directory /pig_data/. This file contains integer and floating point values as shown below.

math.txt

5 
16 
9 
2.5 
5.9 
3.1 

And, we have loaded this file into Pig with a relation named math_data as shown below.

grunt> math_data = LOAD 'hdfs://localhost:9000/pig_data/math.txt' USING PigStorage(',')
   as (data:float);

Let us now calculate the log10 values of the contents of the math.txt file using LOG10() function as shown below.

grunt> log_data = foreach math_data generate (data),LOG10(data);

The above statement stores the result in the relation named log_data. Verify the contents of the relation using the Dump operator as shown below.

grunt> Dump log10_data;
  
(5.0,0.6989700043360189) 
(16.0,1.2041199826559248) 
(9.0,0.9542425094393249) 
(2.5,0.3979400086720376) 
(5.9,0.7708520186620678) 
(3.1,0.4913616804737727)