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Numpy and Matplotlib Error with very Minimal Example

I have been using numpy and matplotlib together for some time now, successfully. Suddenly, I am getting unusual errors when using them together. The following is a minimal example:
import numpy as np
import matplotlib.pyplot as plt
fig,ax = plt.subplots(1,1)
x = np.eye(10)
u = np.linalg.svd(x)
plt.show()
If I run the code once, it works. If I run the code again, I get an exception:
LinAlgError: SVD did not converge. Bizarrely, this behavior disappears when the call to pyplot is removed:
import numpy as np
import matplotlib.pyplot as plt
#fig,ax = plt.subplots(1,1)
x = np.eye(10)
u = np.linalg.svd(x)
#plt.show()
I tried this with two different python environments with numpy versions 18.1 and 18.5. I am wondering if anyone has any information about what could possibly cause this behavior.
edit: I was running these two blocks of code in a jupyter notebook with only those lines of code and nothing else. In order to reproduce the behavior in the interactive interpreter, you need to add the line plt.show() in between runs. I edited the post to include this line.
edit: matplotlib 3.3.2, numpy 18.1 or 18.5, and I can use python 3.8.1 or 3.6.8

Python not showing plots

When I run the following code, plots don't show up even though I am not getting any error messages.
import matplotlib.pyplot as plt
plt.plot = ([1,2], [1,2])
plt.show()
I tried the following
1) Change Spyder->Preferences->Graphics backend = Automatic (Reset kernel)
2)
import matplotlib
matplotlib.use('Agg')
Got error: "no effect because the backend has already been chosen"
I am using Python 3.6 with Spyder that comes with Anaconda

there is an error in your code, it must be:
import matplotlib.pyplot as plt
plt.plot([1,2], [1,2])
plt.show()

Hold is not working for pyplot

I have a problem using pyplot. I am new to Python so sorry if I am doing some obvious mistake.
After I have plotted something using pyplot it shows the graph, but when I then try and add e.g. ylabel it will not update the current graph. It results in a new graph with only the ylabel, not previously entered information. So to me it seems to be a problem with recognizing the current graph/axis, but the ishold delivers a True statement.
My setup is Python 2.7 in Python(x,y). The problem occurs both in the Spyder IDE and the IPython Qt Console. It does however not occur in the regular IPython console (which, by constrast, is not interactive, but everything is included when using show(). When I turn off interactive in Spyder/Qt console it does not show anything after using the show() command).
import matplotlib.pyplot as plt
plt.plot([1,2,3,4])
Out[2]: [<matplotlib.lines.Line2D at 0x78ca370>]

plt.ylabel('test')
Out[3]: <matplotlib.text.Text at 0x5bd5990>

plt.ishold()
Out[4]: True
matplotlib.get_backend()
Out[6]: 'module://IPython.kernel.zmq.pylab.backend_inline'
Hope any of you have some input. Thanks.

This is one of the things were InlineBackend have to behave differently from other backend or you would have sort of a memory leak. You have to keep explicit handle to matplotlib figure and/or set close_figure to False in config. Usually pyplot is a compatibility layer for matlab for convenience, try to learn to do using the Object Oriented way.
fig,ax = subplots()
ax.plot(range(4))
ax.set_ylabel('my label')
...

ipython pandas plot does not show

I am using the anaconda distribution of ipython/Qt console. I want to plot things inline so I type the following from the ipython console:
%pylab inline
Next I type the tutorial at (http://pandas.pydata.org/pandas-docs/dev/visualization.html) into ipython...
import matplotlib.pyplot as plt
import pandas as pd
ts = pd.Series(randn(1000), index = pd.date_range('1/1/2000', periods=1000))
ts = ts.cumsum()
ts.plot()
... and this is all that i get back:
<matplotlib.axes.AxesSubplot at 0x109253410>
But there is no plot. What could be wrong? Is there another command that I need to supply? The tutorial suggests that that is all that I need to type.

Plots are not displayed until you run
plt.show()

There could be 2 ways to approach this problem:
1) Either invoke the inline/osx/qt/gtk/gtk3/tk backend. Depends on the ipython console that you have been using. So, simply do:
%matplotlib inline #Here the inline backend is invoked, which removes the necessity of calling show after each plot.
or for ipython/qt console, do:
%matplotlib qt #This one works for me, thus, depends on the ipython console you use.
#
2) Or, do the traditional way as aforementioned (already answered above on this page):
plt.show() #However, you will have to call this show function each time.

Use pylab to plot image returned from Scipy

I'm working to migrate from MatLab to python in Sage.
So I use these commands and I faced this error in Sage:
from scipy import misc
l = misc.lena();
import pylab as pl
pl.imshow(l)
The Error or message (i don't know) is:
matplotlib.image.AxesImage object at 0xb80198c
And it doesn't show any image

It's not an error, just print the object that method returned.
There are two ways to show the figure:
Add pl.show() after calling pl.imshow(l)
Use ipython --pylab to open your python shell,

That is an object being returned from pylab after using the "imshow" command. That is the location of the Axes image object.
documentation:
http://matplotlib.sourceforge.net/api/pyplot_api.html#matplotlib.pyplot.imshow
Looks like it says it displays the object to the current axes. If you havent already created a plot I imagine you wont see anything
Simple google search suggests this might be what you are looking for
http://docs.scipy.org/doc/scipy/reference/generated/scipy.misc.lena.html

from scipy import misc
l = misc.lena();
import pylab as pl
pl.imshow(l)
####use this
pl.show()