import numpy as np
import gudhi as gd
import random as rd
import matplotlib.pyplot as plt

st = gd.SimplexTree() #Create a simplex tree

#Simplices can be inserted one by one
#Vertices are indexed by integers
if  st.insert([0,1]): 
    print("first simplex inserted!")
st.insert([1,2])
st.insert([2,3])
st.insert([3,0])
st.insert([0,2])
st.insert([3,1])

L = st.get_filtration() #Get a list with all the simplices
#Notice that inserting an edge automatically insert its vertices (if they were 
#not already in the complex)
for splx in L:
    print(splx)

    
#insert the 2-skeleton giving some filtration values to the faces
st.insert([0,1,2],filtration=0.1)
st.insert([1,2,3],filtration=0.2)
st.insert([0,2,3],filtration=0.3)
st.insert([0,1,3],filtration=0.4)

#if you add a new simplex with a given filtration values, all its faces that 
#were not in the complex before are added with the same filtration value
st.insert([2,3,4],filtration=0.7)
L = st.get_filtration()
for splx in L:
    print(splx)    
    
#############################################################################    
#Many operations that can be done on simplicial complexes (see also the Gudhi 
#documentation and examples):
#############################################################################
    
st.set_dimension(2) #Warning! For the moment, the dimension of the simplicial 
#complex has to be set manually

 
print("dimension=", st.dimension())

st.initialize_filtration()
print("filtration=", st.get_filtration())
print("filtration[1, 2]=", st.filtration([1, 2]))
print("filtration[4, 2]=", st.filtration([4, 2]))

print("num_simplices=", st.num_simplices())
print("num_vertices=", st.num_vertices())

print("skeleton[2]=", st.get_skeleton(2))
print("skeleton[1]=", st.get_skeleton(1))
print("skeleton[0]=", st.get_skeleton(0))