Function check_df

pythonwhat/checks/check_object.py:251–300

Check whether a DataFrame was defined and it is the right type ``check_df()`` is a combo of ``check_object()`` and ``is_instance()`` that checks whether the specified object exists and whether the specified object is pandas DataFrame. You can continue checking the data frame with ``che

(state, index, missing_msg=None, not_instance_msg=None, expand_msg=None)

def check_df(state, index, missing_msg=None, not_instance_msg=None, expand_msg=None):
    """Check whether a DataFrame was defined and it is the right type

    ``check_df()`` is a combo of ``check_object()`` and ``is_instance()`` that checks whether the specified object exists
    and whether the specified object is pandas DataFrame.

    You can continue checking the data frame with ``check_keys()`` function to 'zoom in' on a particular column in the pandas DataFrame:

    Args:
        index (str): Name of the data frame to zoom in on.
        missing_msg (str): See ``check_object()``.
        not_instance_msg (str): See ``is_instance()``.
        expand_msg (str): If specified, this overrides any messages that are prepended by previous SCT chains.

    :Example:

        Suppose you want the student to create a DataFrame ``my_df`` with two columns.
        The column ``a`` should contain the numbers 1 to 3,
        while the contents of column ``b`` can be anything: ::

            import pandas as pd
            my_df = pd.DataFrame({"a": [1, 2, 3], "b": ["a", "n", "y"]})

        The following SCT would robustly check that: ::

            Ex().check_df("my_df").multi(
                check_keys("a").has_equal_value(),
                check_keys("b")
            )

        - ``check_df()`` checks if ``my_df`` exists (``check_object()`` behind the scenes) and is a DataFrame (``is_instance()``)
        - ``check_keys("a")`` zooms in on the column ``a`` of the data frame, and ``has_equal_value()`` checks if the columns correspond between student and solution process.
        - ``check_keys("b")`` zooms in on hte column ``b`` of the data frame, but there's no 'equality checking' happening

        The following submissions would pass the SCT above: ::

            my_df = pd.DataFrame({"a": [1, 1 + 1, 3], "b": ["a", "l", "l"]})
            my_df = pd.DataFrame({"a": [1, 2, 3], "b": [4, 5, 6], "c": [7, 8, 9]})

    """
    import pandas as pd
    child = check_object(
        state,
        index,
        missing_msg=missing_msg,
        expand_msg=expand_msg,
        typestr="pandas DataFrame",
    )
    is_instance(child, pd.DataFrame, not_instance_msg=not_instance_msg)
    return child


def check_keys(state, key, missing_msg=None, expand_msg=None):