Helper function for altair exports #8

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1. timvink

   added

   enhancementNew feature or requestNew feature or request

   on Dec 10, 2021
2. ewellinger commented on Jun 1, 2023

   

   ewellinger

   on Jun 1, 2023

   Last edited by ewellinger

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   This might need to be tweaked somewhat, but I created this helper function that roughly follows the logic you're suggesting here:

   import json
   from pathlib import Path
   
   from altair import Chart
   from pydantic import BaseModel, DirectoryPath, validator
   
   
   class ChartParams(BaseModel):
       output_dir: DirectoryPath
       data_file: str
       plot_name: str
   
       @validator("data_file")
       def validate_data_file(cls, val, values):
           if "output_dir" in values:
               full_path = values["output_dir"].absolute() / val
               if not full_path.exists():
                   raise ValueError("data_file does not exist")
           return val
   
       @validator("plot_name")
       def validate_plot_name(cls, val):
           if not val.endswith("json"):
               raise ValueError(f"plot_name must end with .json")
           return val
   
       @property
       def plot_path(self):
           return self.output_dir / self.plot_name
   
   
   def save_chart(chart: Chart, output_dir: Path, data_file: str = "results.csv", plot_name: str = "plot.json") -> None:
       params = ChartParams(output_dir=output_dir, data_file=data_file, plot_name=plot_name)
   
       # Convert the plot to JSON
       plot = json.loads(chart.to_json())
   
       del plot["datasets"]
       plot["data"] = {"url": data_file}
       with open(params.plot_path, "w") as fo:
           json.dump(plot, fo)

   This assumes you're storing the plot in the same directory as the CSV file containing the data.