number of frames is 0

[sjzhao]

Hi Robin,

I start Vmd and type gopython and then load a file by:
molid = molecule.load('parm7', '1BIQ_solvate.top', 'crdbox', 'prod_imaged.mdcrd')
tf = molecule.numframes(molid)
print(tf)
This will give the number of total frames of 300, it works.

However, when I put the same code in a python file like:
from vmd import *
mid = molecule.load('parm7', '1BIQ_solvate.top', 'crdbox', 'prod_imaged.mdcrd')
tf = molecule.numframes(mid)
print('Loaded mid is: ', mid)
print('Total number frames is', tf)

The total number of frames is 0.

Do you have any idea of what is wrong here?
Thanks.

[jvermaas]

Have you looked at the docs? What you are doing in VMD depends on behavior described in the user guide, where molecule.load in VMD 1.9.3 (or I think 1.9.4) will basically wait until all frames are loaded before returning. I think in the rejiggering to get this to work for python3, this side effect disappeared.

[sjzhao]

I just want to load the topo and mdcrd file, then get the total number of frames, and do a for loop base on the frames.
I add a sleep(20) after the load function, but it does not work at all.

[sjzhao]

This is the example from the docs:
from vmd import molecule

molid = molecule.load("parm7", "system.prmtop")
molecule.read(molid, "netcdf", "simulation.nc", skip=5, waitfor=-1)
last_frame = molecule.numframes - 1
molecule.write(molid, "pdb", "last_frame.pdb", first=last_frame)

However, molecule.numframes is a function which require molecule id.
I did molecule.numframes(molid), which return 0