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
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.
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@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.
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
–
Matthew Pulis
URL : http://www.solutions-lab.net
MSN : pulis_matthew[@]hotmail.com
ICQ : 145951110
Skype : solutions-lab.net