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Bug #2873

Simple way to get last frame from trajectory

Added by Mark Abraham 8 months ago. Updated 8 months ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
analysis tools
Target version:
-
Affected version - extra info:
Affected version:
Difficulty:
uncategorized
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Description

At https://mailman-1.sys.kth.se/pipermail/gromacs.org_gmx-users/2019-February/124407.html, a user asked for a simple way to get the last frame from a trajectory.

Currently gmx trjconv -f -dump 9999999 doesn't work because an arbitrary time is observed to be inconsistent with the time series.

We could implement gmx dump -f traj.tng -lastframe conf.gro

History

#1 Updated by Erik Lindahl 8 months ago

  • Tracker changed from Feature to Bug
  • Affected version set to 2019

Since the documentation for the dump option is "Dump frame nearest specified time (ps)", this sounds like it's a bug that it does not do that :-)

Instead of adding another option, IMHO we should just make the present one behave according to the specifications.

#2 Updated by Berk Hess 8 months ago

The specifications are imprecise. I think I implemented this and I think it gives the nearest frame within a the time step between frames.
We can extend it to work exactly to the current specification, but it seems to me that this is not a very intuitive way to get the last frame.

#3 Updated by Mark Abraham 8 months ago

  • Description updated (diff)

#4 Updated by Mark Abraham 8 months ago

For 2019, I suggest we amend the documentation to reflect the behaviour, since making changes to trjconv is undesirable.

For 2020, I suggest we implement something like my earlier suggestion of gmx dump -f -lastframe

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