Question

I have a code in which for 3 different values of D ,i have 3 different values of dx and so,3 different plots.

I want to do a plot which will have all 3 plots in one.

...
D=(0.133e-4,0.243e-4,0.283e-4)

dx=sc.zeros(3)
    for i in D:
        dx[i]=sc.sqrt(D[i]*dt/M)

        plt.ion()
        while n<N:
            Vw_n=Vw_n1
            C_n=C_n1
            R2=(Vw_n+B1)/(Vw_0+B1)
            Cc=C_n1[0]/C0
            F2_1=10000/3*Pw*A*(C0*Vw_0/Vw_n1-C_n[1])
            dV=F2_1*dt
            Vw_n1=Vw_n+dV
            C_n1[0]=C0*Vw_0/Vw_n1
            F_i_2=-D[i]/dx[i]*(C_n[1:7]-C_n[0:6])
            C_n1[0:6]=C_n[0:6]-F_i_2*A*dt/(L/(V0/A)*V0/5)
            n+=1
            ttime=n*0.02*1000

            #-----PLOT AREA---------------------------------#

            mylabels=('T=273','T=293','T=298')
            colors=('-b','or','+k')

            if x==1:
                plt.plot(ttime,R2,mylabels[i],colors[i])
            elif x==2:
                plt.plot(ttime,Cc,mylabels[i],colors[i])
            plt.draw()
            plt.show()

———-RUNNABLE————————–

import scipy as sc
import matplotlib.pyplot as plt


def graph(x):

    A=1.67e-6  
    V0=88e-12 
    Vw_n1=71.7/100*V0 
    Pw=0.22   
    L=4e-4
    B1=V0-Vw_n1   

    C7=0.447e-3  



    dt=0.2e-4
    M=0.759e-1

    C_n1=sc.zeros(7)
    C_n1[0:6]=0.290e-3
    C_n1[6]=0.447e-3


    C0=C_n1[0]
    Vw_0=Vw_n1

    N=2000 
    n =1
    D = ,0.243e-4
    dx = sc.sqrt(D*dt/M)

        plt.ion()
        while n<N:
            Vw_n=Vw_n1
            C_n=C_n1
            R2=(Vw_n+B1)/(Vw_0+B1)
            Cc=C_n1[0]/C0
            F2_1=10000/3*Pw*A*(C0*Vw_0/Vw_n1-C_n[1])
            dV=F2_1*dt
            Vw_n1=Vw_n+dV
            C_n1[0]=C0*Vw_0/Vw_n1
            F_i_2=-D/dx*(C_n[1:7]-C_n[0:6])
            C_n1[0:6]=C_n[0:6]-F_i_2*A*dt/(L/(V0/A)*V0/5)
            n+=1
            ttime=n*0.02*1000

            #-----PLOT AREA---------------------------------#


            if x==1:
                plt.plot(ttime,R2)
            elif x==2:
                plt.plot(ttime,Cc)
            plt.draw()
            plt.show()

My problem is that i want to plot (ttime,R2) and (ttime,Cc).
But i can’t figure how to call R2 and Cc for the 3 different values of D (and dx).

Also, i am taking an error: tuple indices must be integers, not float

at dx[i]=sc.sqrt(D[i]*dt/M).

Thanks!

Answer 1

Consider these lines:

D=(0.133e-4,0.243e-4,0.283e-4)
for i in D:
    dx[i]=sc.sqrt(D[i]*dt/M)

i is a float. It can not be used as an index into the tuple D.
(D[i] does not make sense.)

Perhaps you meant

D=(0.133e-4,0.243e-4,0.283e-4)
for i, dval in enumerate(D):
    dx[i] = sc.sqrt(dval*dt/M)

Or, simply

import scipy as sc
D = sc.array([0.133e-4,0.243e-4,0.283e-4])
dx = sc.sqrt(D*dt/M)

---

• Don’t call plt.plot once for each point. That road leads to
  sluggish behavior. Instead, accumulate an entire curve’s worth of
  data points, and then call plt.plot once for the entire curve.
• To plot 3 curves on the same figure, simply call plt.plot 3 times.
  Do that first before calling plt.show().
• The while not flag loop was not ending when you enter 1 for x,
  because if x==2 should have been elif x==2.
• To animate a matplotlib plot, you should still try to avoid multiple
  calls to plt.plot. Instead, use plt.plot once to make a Line2D
  object, and then update the underlying data with calls to
  line.set_xdata and line.set_ydata. See Joe Kington’s example and this example from the matplotlib docs.

---

import scipy as sc
import matplotlib.pyplot as plt

def graph(x):
    plt.ion()
    fig = plt.figure()
    ax = fig.add_subplot(1, 1, 1)
    lines = []
    D = (0.133e-4, 0.243e-4, 0.283e-4)
    temperatures = ('T = 273','T = 293','T = 298')
    N = 2000
    linestyles = ('ob', '-r', '+m')
    for dval, linestyle, temp in zip(D, linestyles, temperatures):
        line, = ax.plot([], [], linestyle, label = temp) 
        lines.append(line)
    plt.xlim((0, N*0.02*1000))        
    if x == 1:
        plt.ylim((0.7, 1.0))
    else:
        plt.ylim((1.0, 1.6))
    plt.legend(loc = 'best')        
    for dval, line in zip(D, lines):
        A = 1.67e-6
        V0 = 88e-12
        Vw_n1 = 71.7/100*V0
        Pw = 0.22
        L = 4e-4
        B1 = V0-Vw_n1
        C7 = 0.447e-3
        dt = 0.2e-4
        M = 0.759e-1
        C_n1 = sc.zeros(7)
        C_n1[0:6] = 0.290e-3
        C_n1[6] = 0.447e-3
        C0 = C_n1[0]
        Vw_0 = Vw_n1

        tvals = []
        yvals = []
        dx = sc.sqrt(dval*dt/M)
        for n in range(1, N+1, 1):
            Vw_n = Vw_n1
            C_n = C_n1
            R2 = (Vw_n+B1)/(Vw_0+B1)
            Cc = C_n1[0]/C0
            F2_1 = 10000/3*Pw*A*(C0*Vw_0/Vw_n1-C_n[1])
            dV = F2_1*dt
            Vw_n1 = Vw_n+dV
            C_n1[0] = C0*Vw_0/Vw_n1
            F_i_2 = -dval/dx*(C_n[1:7]-C_n[0:6])
            C_n1[0:6] = C_n[0:6]-F_i_2*A*dt/(L/(V0/A)*V0/5)
            tvals.append(n*0.02*1000)
            yvals.append(R2 if x == 1 else Cc)
            if not len(yvals) % 50:
                line.set_xdata(tvals)
                line.set_ydata(yvals)
                fig.canvas.draw()

if __name__ == "__main__":
    flag = False
    while not flag:
        try:
            x = int(raw_input("Give a choice 1  or 2  : "))
            flag = True
            if x == 1:
                plt.title('Change in cell volume ratio as a function of time \n\
                at various temperatures')
                plt.xlabel('Time')
                plt.ylabel('Ceil volume ratio (V/V0)')
                graph(x)
            elif x == 2:
                plt.title('Increase of solute concentration at various temperatures')
                plt.xlabel('Time')
                plt.ylabel('Solute concentration in the Ceil (Cc)')
                graph(x)
            else:
                flag = False
                print("You must input 1 or 2")
        except ValueError:
            print("You must input 1 or 2")
    raw_input('Press a key when done')