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What is LOG10() function?

  • Log10 computes the common (base 10) log of its argument x .
  • The x argument must be a positive double-precision, floating-point number.
  • Log10 returns the common log of its argument, expressed as a double-precision, floating-point number.
 Apache Pig Log10

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LOG10() function in Apache Pig

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

Syntax

grunt> LOG10(expression)

Example

  • Ensure that you have a file named wikitechy_math.txt in the HDFS directory /pig_data/.
  • This file contains integer and floating point values as given below.

wikitechy_math.txt

5 
16 
9 
2.5 
5.9 
3.1 
  • You have loaded this file into Pig with a relation named math_data as given below.
grunt> math_data = LOAD 'hdfs://localhost:9000/pig_data/wikitechy_math.txt' USING PigStorage(',')
   as (data:float);
  • Now you can calculate the log10 values of the contents of the wikitechy_math.txt file using LOG10() function as given below.
grunt> log_data = foreach math_data generate (data),LOG10(data);

Verification

  • Verify the contents of the relation using the Dump operator as given below.
grunt> Dump log10_data;

Output

  • The above statement stores the result in the relation named log_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) 

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