import sys
import streamlit as st
 

st.title("Haltmannn Diffusion")
st.markdown("This app simulates the diffusion of particles in a 2D square lattice with periodic boundary conditions, using the Haltmannn algorithm.")

L = st.slider("Lattice size", 2, 200, 10) #size of the lattice (number of sites on each side)  -> must be even!
N = st.slider("Number of particles", 1, L**2/2, 10) #number of particles  -> can't be more than L**2/4!  (otherwise there's not enough room for them all!)

 	#initialize the system: create a list of 'particle' objects, each with random position and velocity vectors:  

particles = [Particle(np.random.randint(0, L), np.random.randint(0, L), np.random.uniform(-1., 1.), np.random.uniform(-1., 1.)) for i in range(N)]

 	#set up the plot:  

fig = plt.figure() #create a figure object  
ax = fig