from gro_parser import load_system

gro_file_path = 'path/to/your.gro'
top_file_path = 'path/to/your.top'

system = load_system(gro_file_path, top_file_path)

# Browse all residues 
for residue in system.residues:
    print(residue)

# Get a specific residue by index or residue number 
residue = system.get_residue_by_idx(0) 
residue = system.get_residue_by_number(1)

# Get all residues with a specific name
residues_with_name = system.get_residue_by_name('RESIDUENAME')

# Copy a residue. Example : I want to copy the first DOPC of my system. It will insert it at the end of DOPC stack
residue_to_copy = system.get_residue_by_name('DOPC')[0]
residue_to_copy.copy()

# Write the gro file corresponding to the system
system.write_gro('path/to/output.gro')

# Write the top file corresponding to the system
system.write_top('path/to/output.top')