title: Why does Matplotlib locator_params hides negative labels?
body: <p>I'm using "matplotlib locator_params" to reduce the frequency of theta axis labels in the following plot:
  <a href="https://i.stack.imgur.com/KMS3J.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KMS3J.png" alt="enter image description here"></a>
  Using this line of code:</p>
  
  <pre><code>ax.locator_params(axis='x', nbins=30)
  </code></pre>
  
  <p>works fine, but the negative labels are hidden. The result is below:
  <a href="https://i.stack.imgur.com/JXLWf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JXLWf.png" alt="enter image description here"></a>
  How to show back the negative labels ?</p>
  
  <p>Also, how to reduce the number of labels in the r (longitude) direction ? replacing the parameter axis by y instead of x didn't work for me.</p>