Add inplace Argument to dropna

[douglasdennis]

While I was reviewing the code for something else I noticed a dropna call that didn't have inplace set to True and wasn't getting assigned to a new variable. I set inplace to True as it seemed that was what was being done elsewhere in the code. If you prefer the dropna to be removed then I can make that edit instead.

[elbeejay]

Nice catch @douglasdennis and thanks for opening this PR. Would you mind adding a unit test that ensures we get the right behavior moving forward?

Something relatively small like the following should work, you could add it to tests/nwis_test.py. It fails for me using the current master branch, but will pass once your change is implemented.

def test_preformat_peaks_response():
    # make a data frame with a "peak_dt" datetime column
    # it will have some nan and none values
    data = {"peak_dt": ["2000-03-22",
                        "2001-06-08",
                        np.nan,
                        "2002-04-29",
                        "2003-02-23",
                        None,
                        "2003-12-12"],
            "peak_va": [1000,
                        2000,
                        3000,
                        4000,
                        5000,
                        6000,
                        7000]
    }
    # turn data into dataframe
    df = pd.DataFrame(data)
    # run preformat function
    df = preformat_peaks_response(df)
    # assertions
    assert 'datetime' in df.columns
    assert np.isnan(df['datetime']).sum() == 0

[douglasdennis]

I'd be happy to add a test. I should be able to get that done tomorrow. Thank you for putting one together for me!

[douglasdennis]

@elbeejay Sorry for the delay but I added the unit test. The test failure on the previous run looks to be an issue with setting up the build job and not related to this PR. Let me know if I'm missing something though.

[elbeejay]

This looks great, thanks @douglasdennis! Feel free to reach out in the future if you run into problems using dataretrieval or need help designing queries or manipulating the data.