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Accessing Partition of Dataset in Python Recipe

DV
Level 1
Accessing Partition of Dataset in Python Recipe

My goal is to iterate through the different partitions of a dataset, but I'm having trouble accessing the partitions that exist. For more context, I have a set of functions to manipulate the dataframe that is passed through. I would like to  loop through each partition and set that to a dataframe that can be passed through the functions.

 

I tried using the function iter_rows and specifying the partition spec, but I receive an error that the function does not have the argument "partitions". Could you help me understand why the partitions argument is not working and/or an alternative to accessing a partition of a dataset? Is there a way to only choose a partition when running the get_dataframe function?

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DV_3-1579216840816.png

 

Thank you!

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2 Replies
Clément_Stenac
Dataiker
Dataiker

Hi,

Selecting partitions is done on the Dataset object, not at the time of iterating or getting dataframes:

grp = dataiku.Dataset("mydataset")

grp.add_read_partitions(["1"])

for x in grp.iter_rows():
    # This will only retrieve rows of partition 1
    do_stuff()

 

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carlhyde
Level 1

Iterating through pandas dataFrame objects is generally slow. Pandas iteration beats the whole purpose of using DataFrame. It is an anti-pattern and is something you should only do when you have exhausted every other option. It is better look for a List Comprehensions , vectorized solution or DataFrame.apply() method.

Pandas DataFrame loop using list comprehension example

result = [(x, y,z) for x, y,z in zip(df['Name'], df['Promoted'],df['Grade'])]

 

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