Matplotlib graph axis changing [duplicate] - matplotlib

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Closed 1 year ago.
I am trying to make graph using pandas and matplotlib. My data in x and y axis is as follows
Data in X ( It is a python list)
[99.50133729728567,
99.32177485513289,
99.29662080782298,
99.1922871744391,
99.14070177652418,
99.29499371273404,
99.54826208274174,
99.85501632675789,
99.98246755801047,
100.28450605132474,
100.69047659277543,
100.82812684703163,
100.67670430280266,
100.39417022400526,
100.22792692751301,
99.9158443902431,
99.55075159185297,
99.330916993794,
99.37737347787801,
99.62973414137957,
100.01866583740237,
100.42758798072411,
100.56199275721731,
100.48335938102836,
100.313649654463,
100.16496347602485,
99.82351418830224,
99.46621756385987,
99.33208175544729,
99.2794271217398,
99.42925472046936,
99.52825492237166,
99.7573717856461,
99.96122191358516,
100.1013977818942,
100.26595437442364]
Data in Y ( It is a python list)
[100.00020398087408,
100.00043468828244,
100.00050028851648,
100.00030297162272,
99.9997920462273,
99.99883929230562,
99.99906856654064,
99.99950793983656,
99.9986149630411,
99.9982943411356,
99.99939115721274,
100.00021418167366,
100.0008698442229,
100.00061513516697,
100.00129114064856,
100.00151549197089,
100.00027715439002,
100.00023658939669,
99.99899872492574,
99.99747708221712,
99.99758605940052,
99.9990886473757,
100.00046810814177,
100.00045794761733,
100.00090169642483,
100.00184415283576,
100.0021535400512,
100.00079677558163,
100.0005244158289,
99.99967151341512,
100.00009168515908,
99.99958972419704,
99.99920652259239,
99.99939034471534,
99.99908335764445,
100.00043148740218]
I am using following code to make the graph
plt.plot(ss['x'].iloc[0:n], ss['y'].iloc[0:n], linestyle="-", marker='>', label=sector)
plt.legend()
plt.show()
The graph shows like this:
I want to achieve the following:
The x axis seems fine, with scale around 100. But y axis changes the scale on its own as can be seen in the image. While actual y data is of the order of magnitude around 100, the graph has order of magnitude .0011. I am not sure why this change on its own and how to correct it and get around 100.

Answer 1

To find out the range of your Y values you can do this:
print(min(Y), max(Y))
This gives:
99.99747708221712 100.0021535400512
The distance from min(Y) to max(Y) is only 0.0046. That is why matplotlib has plotted the Y axis as a range (-0.002 to +0.002) + an offset of '1e2', which is shown at the top left. '1e2' means "1 x 10 to the power of 2", i.e. 100. Therefore the y-axis range is correct: 99.998 to 100.002.
My guess is, that it shows the labels as -0.002, -0.001, 0.000, ... etc. +1e2 because they are easier to read than 99.998, 99.999, 100.000, ... etc.
UPDATE:
I looked in the documentation and there is a command for setting the tick label behaviour. Use this setting to turn off the behaviour above:
plt.ticklabel_format(axis='y', useOffset=False)
Then the labels are 'normal':