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What is COS() function?
- The cosine function is one of the basic functions encountered in trigonometry (the others being the cosecant, cotangent, secant, sine, and tangent).
- Let be an angle measured counterclockwise from the x-axis along the arc of the unit circle. Then is the horizontal coordinate of the arc endpoint.
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COS() function in Apache pig
- The COS() function of Apache Pig Latin is used to calculate the cosine value of a specified expression.
Syntax:
grunt> COS(expression)
Example:
- Ensure that we have a file named wikitechy_math.txt in the HDFS directory /pig_data/.
- This file contains integer and floating point values is given below.
wikitechy_math.txt
5
16
9
2.5
5.9
3.1
- 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/wikitechy_math.txt' USING PigStorage(',')
as (data:float)
- We are calculate the cosine values of the contents of the wikitechy_math.txt file using COS() function as given below.
grunt> cos_data = foreach math_data generate (data), COS(data);
- Above statement stores the result in the relation named cos_data
Verification:
- Now you can verify the contents of the relation using the Dump operator as shown below.
grunt> Dump cos_data;
Output:
The output shows that the result in the file>cos_data.
(5.0,0.28366218546322625)
(16.0,-0.9576594803233847)
(9.0,-0.9111302618846769)
(2.5,-0.8011436155469337)
(5.9,0.9274784663996888)
(3.1,-0.999135146307834)