[GRASS-user] 3rd Grass Book Data Set

[Matthew Pulis]

Thanks alot Markus for your reply.

May I ask some more questions please to better understand the dataset?

FT_COST;Enhance Routing - Travel time in minutes <- does this mean the time
in minutes taken from Target Id to Source Id depending on the "speed"
column?
TF_COST is Source ID to Target Id right?


And taking the lenght as the cost of going through that node in a routing
network, am I right in the following conclusions :

- I can make another column length with the value of length(the_geom)
- If street is BI-directional, thus one_way = "BI", that means that
cost = length and reverse_cost = length
- If street is TF directional, thus one_way = "TF" that means that cost =
length and reverse_cost = 1000 + length (made 1000 as a big number so for
sure it is not included in the routing)
- If street is FT directional, thus one_way = "FT" that means that cost =
length + 1000 and reverse_cost = length

Now on the dataset is 1000 a huge number? Should I reduce it to a smaller
number / increase it to a bigger number / make it negative?

For my routing I am using pgRouting.


Thanks alot for the time you are investing in GRASS :)


Regards

Matthew

On 12/10/07, Markus Neteler <neteler at fbk.eu> wrote:
>
>
> Matthew,
>
> you can find the legend here:
> http://www.grassbook.org/data_menu3rd.php
> -> ncexternal/: NC original data set sources, metadata and copies of some
> original data
>      -> take metadata link
>               -> Streets.shp ...  streets_wake_legend.csv
>
> Most columns are explained there (as I could reconstruct them from the
> original metadata
> which you also find linked there (see "Data URL")).
>
> Hope this helps,
> Markus
>
>
> Yancho wrote:
> >
> > Hi,
> >
> > Whilst I am waiting for the book to arrive I have started playing a bit
> > with
> > the sample dataset of North Carolina. I am interested in the streets
> layer
> > (dataset) since basiclaly I am about to do some routing work.
> >
> > Can someone please be kind enough to explain to me what do these columns
> > represent?
> >
> > frleft bigint,
> > toleft bigint,
> > frright bigint,
> > toright bigint,
> > frleft_a bigint,
> > toleft_a bigint,
> > frright_a bigint,
> > toright_a bigint,
> > one_way character varying(80),
> > ft_cost numeric,
> > tf_cost numeric,
> > shape_len numeric,
> > length double precision,
> >
> > Also what is the difference between shape_len and length please?
> >
> > My main concern are the one_ways and how I should treat them please.
> >
> > Any help will be extremely appreciated!
> >
> > Regards
> >
> > Matthew
> >
> > --
> > Matthew Pulis
> > URL : http://www.solutions-lab.net
> > MSN : pulis_matthew[@]hotmail.com
> > ICQ : 145951110
> > Skype : solutions-lab.net
> >
>
> --
> View this message in context:
> http://www.nabble.com/3rd-Grass-Book-Data-Set-tp14242058p14244689.html
> Sent from the Grass - Users mailing list archive at Nabble.com.
>
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-- 
Matthew Pulis
URL : http://www.solutions-lab.net
MSN : pulis_matthew[@]hotmail.com
ICQ : 145951110
Skype : solutions-lab.net
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