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 <[EMAIL PROTECTED]> 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 : [EMAIL PROTECTED] > > 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. > > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user > -- Matthew Pulis URL : http://www.solutions-lab.net MSN : [EMAIL PROTECTED] ICQ : 145951110 Skype : solutions-lab.net
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