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From: Shaozhong SHI <shishaozhong@gmail.com>
Date: Thu, 9 Jun 2022 14:37:54 +0100
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Subject: A function to find errors in groups in a table
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There is a table full of grouped values like the following

nodeid     link_type      primary
11           outflowlink       1
11              inflowlink      1
11              outflowlink     2

Primary of 1 indicates a primary water course.  Primary of 2 indicates a
secondary water course.

Obviously, one of the out flow links is an error, as its primacy value is
2.  It is wrong that water flows from a primary water course into a
secondary water course.

How can a function can be designed to find and report such errors?

Regards,

David

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<div dir=3D"ltr"><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail=
_attr">There is a table full of grouped values like the following<br></div>=
<div dir=3D"ltr"><div class=3D"gmail_quote"><div dir=3D"ltr"><div dir=3D"lt=
r"><div><br></div><div>nodeid=C2=A0 =C2=A0 =C2=A0link_type=C2=A0 =C2=A0 =C2=
=A0 primary</div><div><div>11=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0outfl=
owlink=C2=A0 =C2=A0 =C2=A0 =C2=A01</div><div>11=C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 inflowlink=C2=A0 =C2=A0 =C2=A0 1</div><div>11=C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 outflowlink=C2=A0 =C2=A0 =C2=A02<=
/div></div><div><br></div><div>Primary of 1 indicates a primary water cours=
e.=C2=A0 Primary of 2 indicates a secondary water course.</div><div><br></d=
iv><div>Obviously, one of the out flow links is an error, as its primacy va=
lue is 2.=C2=A0 It is wrong that water flows from a primary water course in=
to a secondary water course.</div><div><br></div><div>How can a function ca=
n be designed to find and report such errors?</div><div><br></div><div>Rega=
rds,</div><div><br></div><div>David</div></div></div>
</div></div>
</div></div>

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