X-limits issue with base.assert_line() and seaborn.regplot()

[marty-larocque]

Currently, the documentation for base.assert_line(), reads: "Asserts that there exists a line [that]... goes at least from x coordinate min_val to x coordinate max_val".

More simply, this means that base.assert_line() is checking that the line extends to the limits of the x-data. It is checking that the line extends to the left of the lowest x-value and to the right of the highest x-value.

This can cause an issue when used with seaborn.regplot(). I have attached a plot that is the result of using seaborn.regplot() where the plot appears to be 'cropped in'. The x-limits for the plot partially cut off the outside x-values. (It should be noted that the data for the regression line does not extend past the x-limits of the plot. There isn't any more invisible line past the edges of the plot.)

What this means is that the x-values for the regression do not quite span the same range as the input data. Therefore, if this issue occurs, the assertion will always fail, even if the slope and y-intercept are correct.

This can also be seen on the assignment ea-python-2020-04-lidar-uncertainty.ipynb.

We should change the behavior of base.assert_line() so that this issue does not occur. Likely, this would mean that base.assert_line() would no longer check the min and max x-values of the regression line.

[lwasser]

nathan is working on this here: #248 once we merge this we can add this to @ryla5068 pr's above and add x/y lims as a parameter!

[marty-larocque]

@lwasser this can be closed when #239 is merged.

[nkorinek]

This can be closed, fixed in #274 @lwasser

[lwasser]

holy cow - closing this too thank you!