def read_lammps_data(file_path):

with open(file_path, 'r') as file:

data = file.readlines()

sections = {

'header': [],

'masses': [],

'atoms': [],

'bonds': [],

'angles': [],

'dihedrals': []

}

current_section = None

for line in data:

if 'Masses' in line:

current_section = 'masses'

elif 'Atoms' in line:

current_section = 'atoms'

elif 'Bonds' in line:

current_section = 'bonds'

elif 'Angles' in line:

current_section = 'angles'

elif 'Dihedrals' in line:

current_section = 'dihedrals'

elif len(line.strip()) == 0:

current_section = None

elif current_section is not None:

sections[current_section].append(line.strip())

else:

sections['header'].append(line.strip())

return sections

def merge_lammps_data(file1, file2, output_file):

data1 = read_lammps_data(file1)

data2 = read_lammps_data(file2)

merged_data = {

'header': [],

'masses': [],

'atoms': [],

'bonds': [],

'angles': [],

'dihedrals': []

}

atom_offset = len(data1['atoms'])

bond_offset = len(data1['bonds'])

angle_offset = len(data1['angles'])

dihedral_offset = len(data1['dihedrals'])

# Merge headers (simplified, you may need to merge carefully depending on the content)

merged_data['header'] = data1['header'][:3]

merged_data['header'][2] = f"{atom_offset + len(data2['atoms'])} atoms"

merged_data['header'][3] = f"{bond_offset + len(data2['bonds'])} bonds"

merged_data['header'][4] = f"{angle_offset + len(data2['angles'])} angles"

merged_data['header'][5] = f"{dihedral_offset + len(data2['dihedrals'])} dihedrals"

# Merge masses (assuming same types in both files)

merged_data['masses'] = data1['masses']

# Merge atoms

merged_data['atoms'].extend(data1['atoms'])

for atom in data2['atoms']:

parts = atom.split()

parts[0] = str(int(parts[0]) + atom_offset) # Update atom ID

merged_data['atoms'].append(" ".join(parts))

# Merge bonds

merged_data['bonds'].extend(data1['bonds'])

for bond in data2['bonds']:

parts = bond.split()

parts[0] = str(int(parts[0]) + bond_offset) # Update bond ID

parts[2] = str(int(parts[2]) + atom_offset) # Update atom IDs

parts[3] = str(int(parts[3]) + atom_offset)

merged_data['bonds'].append(" ".join(parts))

# Merge angles

merged_data['angles'].extend(data1['angles'])

for angle in data2['angles']:

parts = angle.split()

parts[0] = str(int(parts[0]) + angle_offset) # Update angle ID

parts[2] = str(int(parts[2]) + atom_offset) # Update atom IDs

parts[3] = str(int(parts[3]) + atom_offset)

parts[4] = str(int(parts[4]) + atom_offset)

merged_data['angles'].append(" ".join(parts))

# Merge dihedrals

merged_data['dihedrals'].extend(data1['dihedrals'])

for dihedral in data2['dihedrals']:

parts = dihedral.split()

parts[0] = str(int(parts[0]) + dihedral_offset) # Update dihedral ID

parts[2] = str(int(parts[2]) + atom_offset) # Update atom IDs

parts[3] = str(int(parts[3]) + atom_offset)

parts[4] = str(int(parts[4]) + atom_offset)

parts[5] = str(int(parts[5]) + atom_offset)

merged_data['dihedrals'].append(" ".join(parts))

with open(output_file, 'w') as file:

for section in ['header', 'masses', 'atoms', 'bonds', 'angles', 'dihedrals']:

file.write("\n".join(merged_data[section]) + "\n\n")

# Usage

merge_lammps_data('file1.data', 'file2.data', 'merged.data')

Muamar Jasim Thanks a lot.