Re: origins/destinations

From: Carson Farmer <carson.farmer@gmail.com>
Subject: [GENERAL] origins/destinations
To: pgsql-general@postgresql.org
Cc: "Carson Farmer" <Carson.Farmer@nuim.ie>
Date: Tuesday, 19 May, 2009, 10:27 PM

Hi list,

I have (what I thought was) a relatively simple problem, but my knowledge of sql is just not good enough to get this done:

I have a table which is basically a number of individuals with both their origin and destination as columns (see Table 1). In this case, origins and destinations are the census area in which they and work. What I would like to do is generate an nxn matrix (preferably output to csv but I'll take what I can get), where origins are on the y axis, and destinations on the x axis (see Table 3).

I can already group by both origins and destinations to produce Table 2, but I don't know what steps are needed to get to Table 3. Any help or suggestions are greatly appreciated!

Table 1

id   |   origin   |   destination
1        area1          area5
2        area1          area5
3        area1          area5
4        area2          area4
5        area4          area2
6        area5          area5
7        area2          area4
8        area2          area4
9        area4          area3
10       area3          area5
...

Table 2

id   |   origin   |   destination  |   count
1        area1          area5            3
4        area2          area4            3
5        area4          area2            1
6        area5          area5            1
9        area4          area3            1
10       area3          area5            1
...

Table 3

origins  |  area1  |  area2  |  area3  |  area4  |  area5  |  ...
area1        0         0         0         0         3
area2        0         0         0         3         0
area3        0         0         0         0         1
area4        0         1         1         0         0
area5        0         0         0         0         1
...


Regards,

Carson

-- Carson J. Q. Farmer
ISSP Doctoral Fellow
National Centre for Geocomputation (NCG),
Email: Carson.Farmer@gmail.com
Web:   http://www.carsonfarmer.com/
      http://www.ftools.ca/



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