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ldump tool


Read dump files with line segment info.


The ldump tool reads one or more LAMMPS dump files, and stores their contents as a series of snapshots with 2d arrays of atom attributes. It is assumed that each atom contains line segment info from a 2d LAMMPS simulation using atom_style line. Other tools use ldump objects to extract line segment info for visualization, like the dump tool via its extra() method.

The constructor method is passed a string containing one or more dump filenames. They can be listed in any order since snapshots are sorted by timestep after they are read and duplicate snapshots (with the same time stamp) are deleted. If a 2nd argument is specified, the files are not immediately read, but snapshots can be read one-at-a-time by the next() method.

The map() method assigns names to columns of atom attributes. The id,type,end1x,end1y,end2x,end2y names must be assigned in order for line segment info to be extracted.

The viz() method is called by tools that visualize snapshots of atoms (e.g. gl, raster, svg tools).

Normally, LAMMPS creates the dump files read in by this tool. If you want to create them yourself, the format of LAMMPS dump files is simple. Each snapshot is formatted as follows:

0 3.35919
0 3.35919
0 7.50
1 1 0 0 0 
2 1 0.25 0.25 0
3 1 0.25 0 0.25
N 3 0.7 0.5 0.6 

The box bounds are listed as xlo xhi on the 1st line, ylo yhi on the next line, zlo zhi on the last. There are N lines following "ITEM: ATOMS" where N is the number of atoms. Atoms do not have to be listed in any particular order. There can be a different number of atoms in each snapshot. Each line must contain the atom ID, type, and the end points of the associated line segment, as specified by the map() command.


l = ldump("")             read in one or more dump files
l = ldump("dump.1 dump.2.gz")	  can be gzipped
l = ldump("dump.*")		  wildcard expands to multiple files
l = ldump("dump.*",0)		  two args = store filenames, but don't read 
  incomplete and duplicate snapshots are deleted
  no column name assignment is performed 
time =             	  read next snapshot from dump files 
  used with 2-argument constructor to allow reading snapshots one-at-a-time
  snapshot will be skipped only if another snapshot has same time stamp
  return time stamp of snapshot read
  return -1 if no snapshots left or last snapshot is incomplete
  no column name assignment is performed,"id",3,"x")               assign names to atom columns (1-N) 
  must assign id,type,end1x,end1y,end2x,end2y 
time,box,atoms,bonds,tris,lines = l.viz(index)   return list of viz objects 
  viz() returns line info for specified timestep index
    can also call as viz(time,1) and will find index of preceding snapshot
    time = timestep value
    box = \[xlo,ylo,zlo,xhi,yhi,zhi\]
    atoms = NULL
    bonds = NULL
    tris = NULL
    lines = id,type,x1,y1,z1,x2,y2,z2 for each line as 2d array
      id,type are from associated atom 
l.owrap(...)		          wrap lines to same image as their atoms 
  owrap() is called by dump tool's owrap()
  useful for wrapping all molecule's atoms/lines the same so it is contiguous 

Related tools:

dump, gl, raster, svg


Numeric or NumPy Python packages. Gunzip command (if you want to read gzipped files).