reductionista commented on a change in pull request #354: Minibatch DL: Set
default normalizing constant to 1.0
URL: https://github.com/apache/madlib/pull/354#discussion_r262746736
##########
File path:
src/ports/postgres/modules/utilities/minibatch_preprocessing_dl.sql_in
##########
@@ -158,7 +159,137 @@ A summary table named \<output_table\>_summary is also
created, which has the fo
@anchor example
@par Examples
--# Create an artificial 2x2 resolution color image data set with 3 possible
classifications:
+-# Create an artificial 2x2 resolution color image data set with 3 possible
classifications.
+The RGB values are per-pixel arrays:
+<pre class="example">
+DROP TABLE IF EXISTS image_data;
+CREATE TABLE image_data AS (
+SELECT ARRAY[
+ ARRAY[(random() * 256)::integer, -- pixel (1,1)
+ (random() * 256)::integer,
+ (random() * 256)::integer],
+ ARRAY[(random() * 256)::integer, -- pixel (2,1)
+ (random() * 256)::integer,
+ (random() * 256)::integer],
+ ARRAY[(random() * 256)::integer, -- pixel (1,2)
+ (random() * 256)::integer,
+ (random() * 256)::integer],
+ ARRAY[(random() * 256)::integer, -- pixel (2,1)
+ (random() * 256)::integer,
+ (random() * 256)::integer]
+ ] as rgb, ('{cat,dog,bird}'::text[])[ceil(random()*3)] as species
+FROM generate_series(1, 52)
+);
Review comment:
If we want to give an example of how we are currently loading the data (and
I think how we were thinking most users would do it), instead of a 4x3 array it
should be a 2x2x3 array like this:
```
SELECT ARRAY[
ARRAY[
ARRAY[(random() * 256)::integer, -- pixel (1,1)
(random() * 256)::integer,
(random() * 256)::integer],
ARRAY[(random() * 256)::integer, -- pixel (2,1)
(random() * 256)::integer,
(random() * 256)::integer]
],
ARRAY[
ARRAY[(random() * 256)::integer, -- pixel (1,2)
(random() * 256)::integer,
(random() * 256)::integer],
ARRAY[(random() * 256)::integer, -- pixel (2,1)
(random() * 256)::integer,
(random() * 256)::integer]
]
]
```
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