Files written to the working directory

Many methods that compute a quantity also write it to a file in the working directory: BANDS.OUT for the band structure, DOS.OUT for the density of states, CHERN.OUT for the Chern number, and so on. This is useful for a script that is plotted later, but in a notebook or inside a larger program the returned arrays are enough, and the files are not needed. Each of these methods has a keyword write with its own default, and filewrite.set_write() sets it for all of them at once:

from pyqula import geometry
from pyqula import filewrite
filewrite.set_write(False) # no routine writes its files from now on
g = geometry.honeycomb_lattice() # honeycomb lattice
h = g.get_hamiltonian() # first-neighbor tight-binding Hamiltonian
(k,e) = h.get_bands() # the band structure, and no BANDS.OUT
(k,e) = h.get_bands(write=True) # a write given in the call wins over the switch
filewrite.set_write(None) # back to the default of each routine

The rule is always the same: first the write given in the call, then the switch, and only if neither is set, the default of the method. So filewrite.set_write(True) makes every method write its file, also the few that do not write by default, such as topology.chern_density(), and write=False in one call keeps that call silent, whatever the switch says. The returned arrays do not depend on this, only the files do. The methods whose only job is to write a file, such as g.write() or h.write_hopping(), always write.