Apache PIG - How to cut digits after decimal point

问题

Is there any possibility to cut a certain area after the decimal point of a float or double number? For example: the result would be 2.67894 => I want to have 2.6 as result (and not 2.7 when rounded).

回答1:

try it.. val is your values like 2.666,3.666,4.666666,5.3456334.....

b = foreach a GENERATE (FLOOR(val * 10) / 10);

dump b;

回答2:

Write a UDF (User Defined Function) for this.

A very simple python UDF (numformat.py):

@outputSchema('value:double')
def format(data):
    return round(data,1)

(Of course you can parametrized the UDF to use different precision.)

Than register and use it in your pig code. Example:

REGISTER numformat.py USING jython as numformat;

A = LOAD 'so/testdata.csv' USING PigStorage(',') AS (data:double);
B = FOREACH A GENERATE numformat.format(data);
DUMP B;

For the following input:

2.1234
12.334

The dumped result is:

(2.1)
(12.3)

来源：https://stackoverflow.com/questions/29922857/apache-pig-how-to-cut-digits-after-decimal-point