Plotting multiple lines to a single Python figure

Question

This is my first Stack Overflow question so please excuse me if the formatting of this question does not follow the conventions of the Stack Overflow community.

My question is how can you (if possible) add a line to an existing Python figure using pyplot? Essentially, what I want to accomplish is I want to compile and run my code and have that generate a figure with a line on it. Then, what I want to do is change some data in the code, compile and run the code again, and then have the line generated from this running of the code show up on the already existing figure.

fig=plt.figure(figsize=(20,10))
time= np.array(range(0, time_steps+1)) 
sigma_11=Q[:, :, :, 0]
sigma_22=Q[:, :, :, 1]
sigma_12=Q[:, :, :, 2]
vel_x=Q[:, :, :, 3]
vel_y=Q[:, :, :, 4]
stiffness_mat=np.mat([[lamda+2*mu, lamda, 0],
                    [lamda, lamda+2*mu, 0],
                    [0, 0, 2*mu]])

Energ_P=np.zeros((time_steps+1))  
Energ_K=np.zeros((time_steps+1))
Energy_tot=np.zeros((time_steps+1))     
    for n in  range(0, time_steps+1):
Energ_P[n]=(Energy_P(stiffness_mat, Q[:, :, n, 0:3]))
Energ_K[n]=(Energy_K(Q[:, :, n, 3:5]))
Energy_tot[n]=Energ_P[n]+Energ_K[n]

sub1=fig.add_subplot(1, 2, 1)  
sub1.set_title('stress-time')
sub1.plot(time*del_t, sigma_11[bar_cells_x, bar_cells_y, :], label='stress_1')
sub1.plot(time*del_t, sigma_11[bar_cells_x/2, bar_cells_y/2, :], label='stress')
sub1.set_ylabel('sigma_11 [Pa]')
sub1.set_xlabel('time [s]')
sub1.legend(loc='best', fontsize='10')

plt.tight_layout()
plt.show()

I haven't really tried much of anything to solve this yet, save running the code multiple times. However, when I do this, all I end up doing is generating multiple figures.

What have you tried so far? Where are you running into problems? Let's see some code!!! — Matt Messersmith
– Matt Messersmith, Commented Jun 24, 2016 at 14:42
Possible duplicate of Adding an arbitrary line to a matplotlib plot in ipython notebook — Destrif
– Destrif, Commented Jun 24, 2016 at 14:44
Despite it's your first question, you should read and follow the conventions. Please, see help page on asking questions — Vladimir Vagaytsev
– Vladimir Vagaytsev, Commented Jun 24, 2016 at 14:50
Your code is not working for the reason NameError: name 'time_steps' is not defined. — SparkAndShine
– SparkAndShine, Commented Jun 24, 2016 at 15:01
You should tag your question with the plotting library's name that you are using. — martineau
– martineau, Commented Jun 24, 2016 at 15:10

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

Try adding the num argument to plt.figure. In other words, replace fig=plt.figure(figsize=(20,10)), with fig=plt.figure(num=1, figsize=(20,10)).

From the docs,

num : integer or string, optional, default: none

If not provided, a new figure will be created, and the figure number will be incremented.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Jun 24, 2016 at 18:40

lanery

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