在Python中更改图形的x和y轴上的值

Question

if I had something like;

import numpy as np, math as m, matplotlib.pyplot as plt
def test():
    x = [1,2,3]
    y = [m.log(0.1),m.log(0.2),m.log(0.3)]

    fig1 = plt.figure()
    plt.plot(x,y)
    plt.show()

This will display a graph with the y axis showing negative numbers. I was wondering how you make the graph display it as a logarithm instead (like what the list y was initially defined to be).

Thanks!

Answer 1

Well the log of a fraction is negative, by the definition of a log. For example 10^x=1/2, x must be negative to get a fractional value. That is the idea behind a log. So your best bet is to display with a log scale so that it displays positive fractions.

The easiest way to do this would be to take 10^x where x is the decimal value, of every y value. Then you will have the y output as decimals, instead of negative numbers.

Then you can set .ylabel() as "log scale".

Edit: I think what you are looking for is answered on this stackoverflow question about making custom ticks. You should be able to use yticks instead of xticks used in the answer.