import scipy.integrate as spi
import numpy as np
# numerical output
print( "..............................................................................................")
print( " simple reaction :1*A -> products,dnAdt = -k*(nA)**1 , no transition state,part 1,version 1.0 ")
print( " peter.vlasschaert@gmail.com,15/01/2023                                                       ")
print( "..............................................................................................")

# transition state = intermediates = complex state.
def reaction(y, t, k):
# order of reaction ordeer = 1    
    nA = y[0]
    dnAdt = -k*(nA)**1
    return [dnAdt]

print( "...........................................................")
print( " simple reaction :dnAdt = -k*(nA)**1 , no transition state ")
print( "...........................................................")

k = 0.1 # reaction rate constant (= fixed value for nA)
nA0 = 1 # initial concentration of A
t = np.linspace(0, 10, 100) # time points for the simulation
y0 = [nA0]
# integration method use : odeint
result = spi.odeint(reaction, y0, t, args=(k,))
print(result) #[[],.......]
nA = result[:,0] # flatten symbolic algebra ( = cas)
print(nA)     #[..........]  
print ("initial value =  nA(0) ")
print( ".......................")
out =[t[0],nA[0]]
print(out)
# use range
print ("print all values over time (use:range       ),nA(t)")

out1=[(t[i],nA[i]) for i in range(len(t))]
# len = length
print(out1)
# use enumerate,test = dummy variable
print ("print all values over time (use:enumerate   ) ,nA(t)")
print( "....................................................")
out2=[(t[i],nA[i]) for i, test in enumerate(t)]
print ("select values over time    (use,integer list) ,nA(t)")
print( "....................................................")
print(out2)
# rem :
# for i, test in enumerate(my_list):
#      print(i, test)
#...................................
# output four first value output
print ("select values over time    (use,integer list) ,nA(t)")
print( "....................................................")
# select values = list of integers 0,1,2,-1, positive or negative
out3=[(i,t[i],nA[i]) for i in [0,1,2,-1]]
# -1, give last value of t=10
print(out3)