Improve chart speed

[David Platten]

When plotting a chart of 1,000,000 studies with the “Remove category whitespace padding“ it takes about 8 seconds to prepare the Pandas dataframe.

This section of chart_functions.py (from line 156) removes any leading and trailing whitespace and also removes any multiple spaces:

    if data_point_name_remove_whitespace_padding:
        df[field_dict["names"]] = df[field_dict["names"]].apply(
            lambda x: x.str.strip().replace("\s+", " ", regex=True)
        )

Replacing it with this code reduces the time to 5 seconds:

    if data_point_name_remove_whitespace_padding:
        # Remove any spaces at start and end of each entry
        df[field_dict["names"]] = df[field_dict["names"]].apply(lambda x: x.str.strip())
        # Remove any multiple spaces
        df[field_dict["names"]] = df[field_dict["names"]].apply(lambda x: x.str.replace("\s+", " ", regex=True))

It’s the same as the first code snippet, but the strip() is run first, and then the replace().