[GRASSLIST:2022] Re: input format of v.net.path in GRASS5.7

[Hayashi Shin-ichiro]

Dear GRASS USERS:

I'm successful to make shortest path vector data.
There are this way as follows.

1.I executed v.net. v.net give nodes point attribute.   
v.net input=walk output=walk_cat nfield=2 operation=nodes

2.Next I executed v.category. v.category gave point category number.    
v.category in=walk_cat out=walk_cate option=add field=2 type=point

3.I executed v.net.path. It worked.
echo "7112 8369" |v.net.path input=walk_cate output=walk_path 

Thank you for your advise heartily, Radim.
I'm very happy!

>On Wednesday 10 December 2003 16:39, Hayashi Shin-ichiro wrote:
>> Dear GRASS users:
>>
>> Thank you very much for your advise, Radim.
>>
>> I tried
>> $ v.net input=walk output=walk_ca
>> 1)My question
>> 1. does v.net give category for all arc and node?
>> 2. Is category number which 1 is arc and 2 is node?
>>
>> I executed v.net.path. Command worked but didn't make any shortest path.
>> $ echo "1 5" |v.net.path input=walk_ca output=walkpath
>> Error messege
>> WARNING: 54667 points without category.
>> WARNING: No point with category 1
>> WARNING: No point with category 5
>>
>> And I tried
>> $ v.category in=walk out=walk_ca option=add
>
>But I had written v.category field=2, so try 
>v.category in=walk out=walk_ca option=add field=2
>echo "1 5" | v.net.path input=walk_ca output=walkpath
>Node numbers may be in from <1,54667>, for example
>echo "123 45678" | v.net.path input=walk_ca output=walkpath
>
>Note that, you can make more SP at the same time
>echo -e "1 2\n3 4" | v.net.path input=walk_ca output=walkpath
>
>> I have same question.
>> 1. does v.category give category for all arc and node?
>> 2. Is category number which 1 is arc and 2 is node?
>>
>> Then I executed v.net.path. Command worked but didn't make any shortest
>> path. GRASS gives me same error messege.
>>
>> I execute d.what.rast. But command tell me only infomation about arc.
>> 2)My question
>> What way can I get infomation about node?
>>
>> My big question is
>> What way can I give category number for node?
>>
>> Please give me your suggestion.
>> Thank you in advance.
>> Sincerely yours.
>
>Try to play a bit with 'type' and 'field' options for v.category and d.what.vect
>to get idea.
>
>Radim
>
>> >Nodes on the network are identified by category number of points
>> >placed exactly on network nodes (ends of lines). If you have lines
>> >only in you vector, you can add new points by v.net and assign categories
>> >to points by v.category field=2. Then use these categories as input for
>> > v.net: echo "1 5" | v.net.path
>

----
Hayashi Shin-ichiro  
mail:forest at bres.tsukuba.ac.jp URL:http://ryuiki.agbi.tsukuba.ac.jp/~forest
Watershed Management Lab., University of TSUKUBA