Hello,
Following what Kevin said about UNION ALL, I have tried to change the
code (below) using UNION ALL and then SELECT DISTINCT (as I need the
same X may be in both functions and I don't want a replicate. But I
still ge the same error (eventual single-point Linestring that should
never happen. Here is the code (so that I don't need to look-up the
previous message:
...header...
SELECT st_LineFromMultiPoint(st_Collect(st_MakePoint(xy.t,xy.at
<http://xy.at/>)))
FROM (SELECT q.t, dr_delay_value($1,q.t) +
dr_delay_value($3,dr_delay_value($1,q.t)) AS at
--- dr_delay_value is a simple look-up function for a certain X
value....
FROM (SELECT st_X(st_PointN($1,n)) AS t
FROM generate_series(1,st_NumPoints($1)) AS h(n)
UNION
SELECT st_X(st_PointN($2,n)) AS t
FROM generate_series(1,st_NumPoints($2)) AS h(n)
UNION
SELECT st_Xmax($1) AS t
) AS q ORDER BY q.t) AS xy
...bottom...
I then changed it to:
SELECT st_LineFromMultiPoint(st_Collect(st_MakePoint(xy.t,xy.at
<http://xy.at/>)))
FROM (SELECT DISTINCT q.t, dr_delay_value($1,q.t) +
dr_delay_value($3,dr_delay_value($1,q.t)) AS at
--- dr_delay_value is a simple look-up function for a certain X
value....
FROM (SELECT st_X(st_PointN($1,n)) AS t
FROM generate_series(1,st_NumPoints($1)) AS h(n)
UNION ALL
SELECT st_X(st_PointN($2,n)) AS t
FROM generate_series(1,st_NumPoints($2)) AS h(n)
UNION
SELECT st_Xmax($1) AS t
) AS q ORDER BY q.t) AS xy
...bottom...
And I know what went inside when I got the error was:
Inputs of function:
$1 = LINESTRING(28800 28809.0366506299,28826.9908145614 28836.029580065)
$2 = LINESTRING(28800 45.4281818181818,28826.9908145614 45.4299607582325)
$3 = LINESTRING(0 43.53,52800 47.01,62700 74.87,86400 43.53) - edge
delay function
Output:
result =
LINESTRING(28800 28854.4654280455) - thus is missing a pair
X=28826.9908145614, Y = 28836.029580065 + Y of $3 for 28836.029580065
But here is what I find most intriguing: if I simulate the inputs
above outside of the main function (in which this one that is
returning an eventual error runs), it simply works.
SELECT
st_AsText(dr_sum_arrivaltime_edgedelay(st_GeometryFromText('LINESTRING(28800
28809.0366506299,28826.9908145614 28836.029580065)'),
st_GeometryFromText('LINESTRING(28800
45.4281818181818,28826.9908145614 45.4299607582325)'),
st_GeometryFromText('LINESTRING(0
43.53,52800 47.01,62700 74.87,86400 43.53)')))
= "LINESTRING(28800 28854.4654280455,28826.9908145614 28881.46013656)"
I hope anyone can give me a clue on that one. It's sort of really
bothering already, as I can't imagine why that happens...
Best regards,
Rodrigo Sperb
------------------------------
Message: 7
Date: Sun, 08 Nov 2009 09:25:37 -0800
From: Kevin Neufeld <[email protected]
<mailto:[email protected]>>
Subject: Re: [postgis-users] Is that possible a function to behave
differently inside and outside another main function code?
To: PostGIS Users Discussion
<[email protected]
<mailto:[email protected]>>
Message-ID: <[email protected]
<mailto:[email protected]>>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Are you sure you want to use "UNION" and not "UNION ALL"? The former
will remove duplicates, the latter does not. It's conceivable
that when
UNIONed, the three SELECT st_X clauses will return a single value.
Collected and put through ST_LineFromMultiPoint would probably
result in
a single point line (depending on which version of PostGIS you are
using
- the newer versions will ERROR with "geometry requires more points").
Hope that helps,
Kevin
rodrigosperb wrote:
> Hello,
>
> I have a bit of a problem that is sort of driving me crazy. I
need to
> perform an "addition of two (mathematical) functions". I
represent them as
> linestrings in my solution, and it is part of another bigger
function. The
> code is as follows:
>
> ...header...
> SELECT st_LineFromMultiPoint(st_Collect(st_MakePoint(xy.t,xy.at
<http://xy.at>)))
> FROM (SELECT q.t, dr_delay_value($1,q.t) +
> dr_delay_value($3,dr_delay_value($1,q.t)) AS at
> FROM (SELECT st_X(st_PointN($1,n)) AS t
> FROM generate_series(1,st_NumPoints($1)) AS h(n)
> UNION
> SELECT st_X(st_PointN($2,n)) AS t
> FROM generate_series(1,st_NumPoints($2)) AS h(n)
> UNION
> SELECT st_Xmax($1) AS t
> ) AS q ORDER BY q.t) AS xy
> ...bottom...
> dr_delay_value() is simply a look-up function that takes the Y
value for a
> certain X.
>
> The thing is that eventually this fuction is failing on
returning more
> specifically a 2-points linestring (that sould) and returns only
a single
> point one. Now, I have prepared a "wrapper" PL/Pgsql function to
keep track
> of what is passed to that function (perhaps that was the reason
for the
> error. With that I'm pretty much sure that the arguments passed
are fine,
> and still get the same error... Strangely, with my wrapper
function keeping
> track of the arguments passed to the function I was able to try
out to run
> the same request (that inside of the bigger function fails)
separately, and
> guess what? is simply works!!
>
> I hope anyone may have a clue of what is going on. That's a very
strange
> behavior, I would say.
>
> Regards,
>
> Rodrigo Sperb
>
------------------------------
Message: 8
Date: Sun, 8 Nov 2009 09:26:41 -0800 (PST)
From: rodrigosperb <[email protected]
<mailto:[email protected]>>
Subject: Re: [postgis-users] Is that possible a function to behave
differently inside and outside another main function code?
To: [email protected]
<mailto:[email protected]>
Message-ID: <[email protected]
<mailto:[email protected]>>
Content-Type: text/plain; charset=us-ascii
Hi Kevin,
Thanks for your repply. I can't be sure whether the two functions
have the
same X value, and I don't want them twice, that's why I was using
UNION,
instead of UNION ALL (which is much faster even...).
But what you said make some sense. Do you think if use first a
UNION ALL and
then in the outer query (when I order by q.t) I use DISTINCT may work?
I think I will try it out.
Thanks again for the help.
Rodrigo Sperb
Kevin Neufeld wrote:
>
> Are you sure you want to use "UNION" and not "UNION ALL"? The
former
> will remove duplicates, the latter does not. It's conceivable
that when
> UNIONed, the three SELECT st_X clauses will return a single value.
> Collected and put through ST_LineFromMultiPoint would probably
result in
> a single point line (depending on which version of PostGIS you
are using
> - the newer versions will ERROR with "geometry requires more
points").
>
> Hope that helps,
> Kevin
>
> rodrigosperb wrote:
>> Hello,
>>
>> I have a bit of a problem that is sort of driving me crazy. I
need to
>> perform an "addition of two (mathematical) functions". I
represent them
>> as
>> linestrings in my solution, and it is part of another bigger
function.
>> The
>> code is as follows:
>>
>> ...header...
>> SELECT st_LineFromMultiPoint(st_Collect(st_MakePoint(xy.t,xy.at
<http://xy.at>)))
>> FROM (SELECT q.t, dr_delay_value($1,q.t) +
>> dr_delay_value($3,dr_delay_value($1,q.t)) AS at
>> FROM (SELECT st_X(st_PointN($1,n)) AS t
>> FROM generate_series(1,st_NumPoints($1)) AS h(n)
>> UNION
>> SELECT st_X(st_PointN($2,n)) AS t
>> FROM generate_series(1,st_NumPoints($2)) AS h(n)
>> UNION
>> SELECT st_Xmax($1) AS t
>> ) AS q ORDER BY q.t) AS xy
>> ...bottom...
>> dr_delay_value() is simply a look-up function that takes the Y
value for
>> a
>> certain X.
>>
>> The thing is that eventually this fuction is failing on
returning more
>> specifically a 2-points linestring (that sould) and returns
only a single
>> point one. Now, I have prepared a "wrapper" PL/Pgsql function
to keep
>> track
>> of what is passed to that function (perhaps that was the reason
for the
>> error. With that I'm pretty much sure that the arguments passed
are fine,
>> and still get the same error... Strangely, with my wrapper function
>> keeping
>> track of the arguments passed to the function I was able to try
out to
>> run
>> the same request (that inside of the bigger function fails)
separately,
>> and
>> guess what? is simply works!!
>>
>> I hope anyone may have a clue of what is going on. That's a
very strange
>> behavior, I would say.
>>
>> Regards,
>>
>> Rodrigo Sperb
>>
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> [email protected]
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> http://postgis.refractions.net/mailman/listinfo/postgis-users
>
>
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