creating inset in matplot lib

Question

I have created a plot in matplot lib and I wish to add an inset to that plot. The data I wish to plot is kept inside of a dictionary that I use in other figures. I'm finding this data inside a loop which I then run this loop again for the subplot. Here is the relevant segment:

leg = []     
colors=['red','blue']
count = 0                     
for key in Xpr: #Xpr holds my data
    #skipping over what I don't want to plot
    if not key[0] == '5': continue 
    if key[1] == '0': continue
    if key[1] == 'a': continue
    leg.append(key)
    x = Xpr[key]
    y = Ypr[key] #Ypr holds the Y axis and is created when Xpr is created
    plt.scatter(x,y,color=colors[count],marker='.')
    count += 1

plt.xlabel(r'$z/\mu$')
plt.ylabel(r'$\rho(z)$')
plt.legend(leg)
plt.xlim(0,10)
#Now I wish to create the inset
a=plt.axes([0.7,0.7,0.8,0.8])
count = 0
for key in Xpr:
    break
    if not key[0] == '5': continue
    if key[1] == '0': continue
    if key[1] == 'a': continue
    leg.append(key)
    x = Xpr[key]
    y = Ypr[key]
    a.plot(x,y,color=colors[count])
    count += 1
plt.savefig('ion density 5per Un.pdf',format='pdf')

plt.cla()

The strange thing is that when I tried to move the inset position, I still get the previous insets (those from the previous run of the code). I even tried to comment out the a=axes([]) line without any apparent. I attach en example file. Why is it acting in that way?

Answer 1

The simple answer is you should use plt.clf() which clears the figure, not the current axes. There is also a break in the inset loop which means none of that code will ever run.

When you start to do more complicated things than use a single axes, it is worth switching over to using the OO interface to matplotlib. It may seem more complicated at first, but you no longer have to worry about the hidden state of pyplot. Your code can be re-written as

fig = plt.figure()
ax = fig.add_axes([.1,.1,.8,.8]) # main axes
colors=['red','blue']
for key  in Xpr: #Xpr holds my data
    #skipping over what I don't want to plot
    if not key[0] == '5': continue 
    if key[1] == '0': continue
    if key[1] == 'a': continue
    x = Xpr[key]
    y = Ypr[key] #Ypr holds the Y axis and is created when Xpr is created
    ax.scatter(x,y,color=colors[count],marker='.',label=key)
    count += 1

ax.set_xlabel(r'$z/\mu$')
ax.set_ylabel(r'$\rho(z)$')
ax.set_xlim(0,10)
leg = ax.legend()

#Now I wish to create the inset
ax_inset=fig.add_axes([0.7,0.7,0.3,0.3])
count =0
for key  in Xpr: #Xpr holds my data
    if not key[0] == '5': continue
    if key[1] == '0': continue
    if key[1] == 'a': continue
    x = Xpr[key]
    y = Ypr[key]
    ax_inset.plot(x,y,color=colors[count],label=key)
    count +=1

ax_inset.legend()