PCA step by step

I have found the great step by step Python tutorial to PCA:

http://sebastianraschka.com/Articles/2014_pca_step_by_step.html

Joomla webpages

After long time I have opened webpages of my FRVS project created in Joomla. I have faced few problems. This is not a tutorial, just few things which I found out I have forgotten after few months...

How to edit Joomla webpages on localhost?
open localhost\...\administrator (administrator instead of index.html or index.php)

How to add new article?
Add article into article manager
- add article within existing category and into menu item which is a list of Category articles (maybe necessary to add new Category in Category manager)
- or in Menu manager add new menu item (with single article content) and link to the created article

How to link to file?
- Upload file through Media manager
- Add link to text which will link to a file (icon Link in Article editor)-> Browse for a link and select a file you want to link to

How to add zip files to Joomla:
It is not default option. Go to Media manager->Options->add ZIP and zip into list of allowed extensions

How to upload Joomla webpages on web:
1. Upload your newly created Joomla site to the server via FTP.
2. Create the MySql Database.
3. Edit the configuration.php file and set the newly created server database name, username, password correctly. U don't have to change the host name usually its "localhost" but if your server MySql is belong to a different IP u need to put that ip in the hostname.
4. upload/replace the configuration.php file.
5. Export your Local Joomla(PC) database (e.g using PhpMyadmin) and import the same in your Server Database.

SQL - Different where conditions for two columns

Just some programming note. When dealing with SQL database you can face the problem how to select two or more columns with different conditions. Here is the solution based on the CASE:

This problem is also discussed on internet for example here: http://stackoverflow.com/questions/3087314/sql-two-different-where-conditions-for-two-columns