[jira] [Created] (MADLIB-1187) Modify knn help funtion for easier use

["Jingyi Mei (JIRA)" <ji...@apache.org>]

Jingyi Mei created MADLIB-1187:
----------------------------------

             Summary: Modify knn help funtion for easier use
                 Key: MADLIB-1187
                 URL: https://issues.apache.org/jira/browse/MADLIB-1187
             Project: Apache MADlib
          Issue Type: Improvement
          Components: k-NN
            Reporter: Jingyi Mei
             Fix For: v2.0


Follow on to 
https://issues.apache.org/jira/browse/MADLIB-927

Currently, the madlib knn help function only supports the following input arguments with lower case: ' ',  'help', 'usage', '?'.

At the same time, the help message was implemented as a psql NOTICE, which means if the user set the message level in db higher than NOTICE (e.g. WARNING), the notice won't get printed out.
An example is like:
```
ALTER DATABASE madlib SET client_min_messages TO WARNING;
madlib=# select madlib.knn();
 knn
-----

(1 row)
```
while the normal case should look like this:
```
madlib=# select madlib.knn();
NOTICE:
k-Nearest Neighbors is a method for finding k closest points to a given data
DETAIL:
point in terms of a given metric. Its input consist of data points as features
from testing examples. For a given k, it looks for k closest points in
training set for each of the data points in test set. Algorithm generates one
output per testing example. The output of KNN depends on the type of task:
For Classification, the output is majority vote of the classes of the k
nearest data points. The testing example gets assigned the most popular class
among nearest neighbors. For Regression, the output is average of the values
of k nearest neighbors of the given testing example.
 knn
-----

(1 row)
```
In this case, we decide to do the following improvement to the help funtion:
1. instead of a `RAISE NOTICE` in udf definition, we are going to implement it in a plpython so the help message can always get printed out.
2. add 'example' also as a valid input argument, and make all the input arguments ignore upper and lower cases



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)