Transformer

​

Example

from pandas import DataFrame


@transformer
def transform_df(df: DataFrame, *args, **kwargs) -> DataFrame:
    return df.iloc[:10]

​

How data is received from upstream blocks

All blocks (except Scratchpads and Sensors) pass their data from the return statement in their decorated function to all their downstream blocks.

In order to access the data from an upstream block within a current block, use the positional arguments of the decorated function.

For example, in the above function named transform_df, the output data from its upstream block is accessed by the positional argument named df.

​

Getting data from multiple upstream blocks

If a block has more than 1 upstream block, then each upstream block’s output is accessible via positional arguments.

For example, if you have 3 upstream blocks, than there will be 3 positional arguments available within the transform_df function.

See below for an example:

from pandas import DataFrame
import pandas as pd


@transformer
def transform_df(df1, df2, df3, **kwargs) -> DataFrame:
    return pd.concat([df1, df2, df3])