Opened 15 years ago

Closed 14 years ago

#105 closed enhancement (fixed) zscale parameter addition patch

Reported by: neteler Owned by: hamish
Priority: major Milestone: 6.4.0
Component: Default Version: svn-trunk
Keywords: Cc: grass-dev@…
CPU: Unspecified Platform: Unspecified



I have implemented a zscale parameter in Patch submitted to trac for review.


Attachments (1)

diff (3.3 KB ) - added by neteler 15 years ago. new zscale param

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Change History (8)

by neteler, 15 years ago

Attachment: diff added new zscale param

comment:1 by hamish, 15 years ago

Cc: grass-dev@… added
Owner: changed from grass-dev@… to hamish
Status: newassigned


Sorry I missed the earlier discussion of the -i flag [for ignoring malformed lines in the data stream]; I had been out of town.

In general my plan for was to keep the interface (and code) as simple as possible. The idea is to keep the methodology clean + light, and so the code bug free + fast.

The code for the -i flag won't slow down the module any (vs prior) and doesn't really add program complexity, so I don't have a technical problem with it. Still, for reducing methodology mistakes & encouraging a hands-on approach to data management, I consider it preferable that the user should be forced to do something to fix their broken input files rather than hack their way around them without careful study of what the problem really is. If there are many files to process they could filter the stream through any number of UNIX tools like sed or awk and then pipe the result to's stdin in some automated way.


A zscale= option seems like a reasonable request. Is the purpose that the elevation data comes in feet and you want it in meters?

I will review the patch, run some speed tests, and take care of committing as soon as time allows.


comment:2 by neteler, 15 years ago

I would appreciate if you don't revert the -i flag. It's a major PITA to manually fix files as in the indicated case (with Lidar, you often have hundreds of tiles to process).

The purpose that the elevation data comes in feet and you want it in meters or you want centimeters or whatever. Data often come in a different way than desired.


comment:3 by hamish, 15 years ago

Don't worry, I don't mean to revert the -i flag, but I did want to make clear my design philosophy. If the input file is that badly broken then a million WARNINGs should be disincentive enough to discourage lazy abuse of the flag.

FWIW, to chop off the last row of a file, use head with a negative index:

head -n -1 filename.txt | in=- out=foo ...


comment:4 by hamish, 14 years ago

Keywords: added

Patch committed by Markus; looks good. Closing wish.


comment:5 by hamish, 14 years ago

Resolution: fixed
Status: assignedclosed

comment:6 by hamish, 14 years ago

Resolution: fixed
Status: closedreopened

shouldn't that be z *= zscale; ??


comment:7 by hamish, 14 years ago

Resolution: fixed
Status: reopenedclosed

With r31713's zscale has been changed in svn to multiply by the scale factor, not divide.

reclosing ticket.


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