Remove unwanted minor tick label for log plots

[pingelit]

Which issue(s) are closed by this pull request?

Closes #71

Changes proposed in this pull request:

• Disable the minor tick labels for log axis to remove the unwanted tick labels.

[pingelit]

So far I've only added this to the freq plot, due to some open questions:

• Is this what we want? Log formatter for plots adds unwanted ticks in scientific notation #71 suggests another approach.
• Should this be the default, even for freq_scale='linear'

[f-brinkmann]

Thanks for checking, I think it resolves the issue. I did not see any effect on linear axes. Applying it only to log. frequency axis might be the cleaner solution as it would maintain as much Matplotlib default behavior as possible.

[mberz]

Just minor things.
I'd also agree to not use this for linearly scaled axes.
We should not close #71 though, or create a new issue, since this only fixes part of the issue. The other problem is that one may end up with a very low number (or on extreme cases none) of major ticks when zooming in on the frequency axis.

[mberz]

Suggested change

	from matplotlib.ticker import (
	NullFormatter
	)
	from matplotlib.ticker import NullFormatter

[mberz]

Suggested change

	from matplotlib.ticker import (
	NullFormatter
	)
	from matplotlib.ticker import NullFormatter

[f-brinkmann]

Agreed and opened a new issue with a more specific name #451

[pingelit]

Just fixed the comments from @mberz.
Before opening the pull request, I want to check if this behavior can be unit tested.

[f-brinkmann]

Thanks for implementing!