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The accepted answer will work, but will run df.count() for each column, which is quite taxing for a large number of columns. Calculate it once before the list comprehension and save yourself an enormous amount of time: def drop_null_columns(df): """ This function drops columns containing all null values. :param df: A PySpark ...


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You probably mean "MapReduce" by "Hadoop". MapReduce is an older model where each operation took input from storage, computed, wrote results to storage. Of course, many real-world tasks involve lots of operations - read, filter, transform, aggregate, etc. Expressing those in MapReduce would be difficult, and what's more, every single ...


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This could work. Suppose if your column name is "Marital status" and categorical, v1=dataset['Marital status'].unique() dataset['Marital status'].replace(to_replace=v1,value= list(range(len(v1))), inplace=True)


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Possible answer from here The problem is that you're trying to pickle an object from the module where it's defined. If you move the class into a separate file and import it into your script, then it should work. That solution isn't viable for me in an iPython notebook though. So here I some additional information from here Python's pickle actually does ...


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