Plot logarithmic axes with matplotlib in python

Question

I want to plot a graph with one logarithmic axis using matplotlib    I ve been reading the docs  but can t figure out the syntax  I know that it s probably something simple like  scale linear  in the plot arguments  but I can t seem to get it right  Sample program    import pylab import matplotlib pyplot as plt a    pow 10  i  for i in range 10   fig   plt figure   ax   fig add subplot 2  1  1   line    ax plot a  color  blue   lw 2  pylab show

User · Answer

First of all  it s not very tidy to mix pylab and pyplot code  What s more  pyplot style is preferred over using pylab   Here is a slightly cleaned up code  using only pyplot functions   from matplotlib import pyplot  a     pow 10 i  for i in range 10     pyplot subplot 2 1 1  pyplot plot a  color  blue   lw 2  pyplot yscale  log   pyplot show     The relevant function is pyplot yscale    If you use the object-oriented version  replace it by the method Axes set yscale    Remember that you can also change the scale of X axis  using pyplot xscale    or Axes set xscale      Check my question What is the difference between    log    and    symlog     to see a few examples of the graph scales that matplotlib offers

User · Answer

if you want to change the base of logarithm  just add  plt yscale  log  base 2    Before Matplotlib 3 3  you would have to use basex basey as the bases of log

User · Answer

I know this is slightly off-topic  since some comments mentioned the ax set yscale  log   to be  nicest  solution I thought a rebuttal could be due  I would not recommend using ax set yscale  log   for histograms and bar plots  In my version  0 99 1 1  i run into some rendering problems - not sure how general this issue is  However both bar and hist has optional arguments to set the y-scale to log  which work fine   references  http   matplotlib org api pyplot api html matplotlib pyplot bar  http   matplotlib org api pyplot api html matplotlib pyplot hist

User · Answer

So if you are simply using the unsophisticated API  like I often am  I use it in ipython a lot   then this is simply  yscale  log   plot        Hope this helps someone looking for a simple answer

User · Answer

You can use the Axes set yscale method  That allows you to change the scale after the Axes object is created  That would also allow you to build a control to let the user pick the scale if you needed to   The relevant line to add is   ax set yscale  log     You can use  linear  to switch back to a linear scale  Here s what your code would look like   import pylab import matplotlib pyplot as plt a    pow 10  i  for i in range 10   fig   plt figure   ax   fig add subplot 2  1  1   line    ax plot a  color  blue   lw 2   ax set yscale  log    pylab show

User · Answer

You simply need to use semilogy instead of plot   from pylab import   import matplotlib pyplot  as pyplot a     pow 10 i  for i in range 10    fig   pyplot figure   ax   fig add subplot 2 1 1   line    ax semilogy a  color  blue   lw 2  show

[python] Plot logarithmic axes with matplotlib in python

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