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# ask-ai
l

Lucas Humbert

02/21/2024, 1:42 PM
I have one ops which return a list and a second one which return a pandas dataframe. I need to compare the 2 results. I want to convert the dataframe into list to have a list comparison in a third ops. Could you write me the code doing the whole
s

Scout

02/21/2024, 1:42 PM
Based on the documentation, I can guide you through the process of comparing the results of two ops, one returning a list and the other returning a pandas DataFrame, and then performing a list comparison in a third op. However, I will not be able to provide a custom code example that is not found in the documentation. Here's a step-by-step explanation of how you might set up your ops and the comparison logic: 1. First Op: This op returns a list. Let's call it
op_returning_list
. 2. Second Op: This op returns a pandas DataFrame. Let's call it
op_returning_dataframe
. 3. Third Op: This op will take the outputs of the first two ops, convert the DataFrame to a list, and then perform the comparison. Let's call it
compare_lists_op
. The third op would look something like this, based on the functions described in the documentation:
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python
from dagster import op, Out
import pandas as pd

@op
def op_returning_list():
    # Your logic here
    return some_list

@op
def op_returning_dataframe():
    # Your logic here
    return some_dataframe

@op
def compare_lists_op(list_result, dataframe_result):
    # Convert DataFrame to list
    dataframe_as_list = dataframe_result.values.tolist()
    
    # Perform comparison
    comparison_result = list(set(list_result) & set(dataframe_as_list))
    
    # You can now work with the comparison_result
    # For example, return it or print it
    return comparison_result
In the above code,
dataframe_result.values.tolist()
is used to convert the DataFrame to a list of lists. If you want to flatten this list of lists into a single list (assuming the DataFrame is one-dimensional), you could use a list comprehension or another method to do so. Please note that the actual implementation of the comparison logic will depend on the specific details of your comparison (e.g., whether you're comparing values directly, whether you need to handle nested lists, etc.). To wire these ops together in a job, you would use a graph:
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python
from dagster import graph, execute_graph

@graph
def my_comparison_graph():
    list_result = op_returning_list()
    dataframe_result = op_returning_dataframe()
    compare_lists_op(list_result, dataframe_result)

# Convert the graph to a job to execute it
my_comparison_job = my_comparison_graph.to_job()
Remember to replace the placeholder logic in
op_returning_list
and
op_returning_dataframe
with your actual logic for generating the list and DataFrame, respectively. To execute the job, you would call
execute_graph
with the appropriate parameters:
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python
if __name__ == "__main__":
    result = execute_graph(my_comparison_job)
This is a high-level guide based on the functions and concepts provided in the documentation. For a more detailed implementat
ion, you would need to adapt this to your specific use case and ensure that all necessary imports and data types are correctly handled.
l

Lucas Humbert

02/21/2024, 1:46 PM
The op you called "compare_lists_op" must take 2 lists in parameters. I need to convert my dataframe into before this ops. How do you do that ?
@Scout The op you called "compare_lists_op" must take 2 lists in parameters. I need to convert my dataframe into before this ops. How do you do that ?
s

Scout

02/21/2024, 1:48 PM
To convert a pandas DataFrame to a list before passing it to the
compare_lists_op
, you can create an intermediate op that performs the conversion. This op will take the DataFrame as input, convert it to a list, and then output that list. Here's how you can define this intermediate op:
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python from dagster import op  @op def dataframe_to_list(dataframe_result):     # Assuming you want to convert the entire DataFrame into a list of values     # This will create a list of lists if the DataFrame has multiple columns     list_from_dataframe = dataframe_result.values.tolist()          # If you want to flatten the list of lists into a single list (for a single column DataFrame)     # You can use a list comprehension or itertools.chain     # flattened_list = [item for sublist in list_from_dataframe for item in sublist]          return list_from_dataframe
Now, you can use this intermediate op in your graph to convert the DataFrame to a list before passing both lists to the `compare_lists_op`:
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python from dagster import graph  @graph def my_comparison_graph():     list_result = op_returning_list()     dataframe_result = op_returning_dataframe()     list_from_dataframe = dataframe_to_list(dataframe_result)     compare_lists_op(list_result, list_from_dataframe)  # Convert the graph to a job to execute it my_comparison_job = my_comparison_graph.to_job()
The
compare_lists_op
will now receive two lists as its inputs:
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python @op def compare_lists_op(list1, list2):     # Perform comparison     comparison_result = list(set(list1) & set(list2))          # You can now work with the comparison_result     # For example, return it or print it     return comparison_result
This setup ensures that the DataFrame is converted to a list before the comparison takes place in
compare_lists_op
. Remember to adjust the conversion logic in
dataframe_to_list
based on the structure of your DataFrame and how you want the data to be represented in the list format.
🎉 1
l

Lucas Humbert

02/21/2024, 1:56 PM
@Scout python difference between 2 lists of string return as a list of string
s

Scout

02/21/2024, 1:56 PM
To find the difference between two lists of strings in Python, you can use set operations to identify items that are unique to each list. Here's an example of how you can do this:
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python def difference_between_lists(list1, list2):     # Convert lists to sets to perform set operations     set1 = set(list1)     set2 = set(list2)      # Find the difference between the two sets     # This will return items that are in set1 but not in set2     difference = set1 - set2      # Convert the set back to a list of strings     difference_list = list(difference)      return difference_list  # Example usage: list_a = ["apple", "banana", "cherry"] list_b = ["banana", "kiwi", "apple"]  # Find items in list_a that are not in list_b result = difference_between_lists(list_a, list_b) print(result)  # Output: ['cherry']
In this example,
difference_between_lists
function takes two lists of strings, converts them to sets, and then calculates the difference using the
-
operator. The result is a set containing elements that are in
list1
but not in
list2
. Finally, the set is converted back to a list of strings and returned. If you want to find items that are unique to each list (i.e., in
list1
but not in
list2
, and vice versa), you can use the symmetric difference operation:
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python def symmetric_difference_between_lists(list1, list2):     # Convert lists to sets to perform set operations     set1 = set(list1)     set2 = set(list2)      # Find the symmetric difference between the two sets     # This will return items that are unique to each set     symmetric_difference = set1 ^ set2      # Convert the set back to a list of strings     symmetric_difference_list = list(symmetric_difference)      return symmetric_difference_list  # Example usage: result = symmetric_difference_between_lists(list_a, list_b) print(result)  # Output may vary in order, e.g., ['cherry', 'kiwi']
The
symmetric_difference_between_lists
function uses the
^
operator to find the symmetric difference between the two sets, which includes elements that are in either
set1
or
set2
but not in both. The result is then converted back to a list of strings. Note that the order of items in the output list may vary because sets do not maintain order.
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