filter_data

Instructions

Implementation Reference

• src/visidata_mcp/server.py:323-404 (handler)

  The filter_data tool implementation - filters data based on column conditions (equals, contains, greater_than, less_than) using pandas, with optional output to save filtered results

  @mcp.tool()
  def filter_data(file_path: str, column: str, condition: str, value: str, output_path: Optional[str] = None) -> str:
      """
      Filter data based on a condition.
      
      Args:
          file_path: Path to the data file
          column: Column name to filter on
          condition: Filter condition (equals, contains, greater_than, less_than)
          value: Value to filter by
          output_path: Optional path to save filtered data
      
      Returns:
          Information about the filtered data
      """
      try:
          import pandas as pd
          from pathlib import Path
          
          file_extension = Path(file_path).suffix.lower()
          
          # Load with pandas
          if file_extension == '.csv':
              df = pd.read_csv(file_path)
          elif file_extension == '.json':
              df = pd.read_json(file_path)
          elif file_extension in ['.xlsx', '.xls']:
              df = pd.read_excel(file_path)
          elif file_extension == '.tsv':
              df = pd.read_csv(file_path, sep='\t')
          else:
              df = pd.read_csv(file_path)
          
          if column not in df.columns:
              return f"Error: Column '{column}' not found. Available columns: {list(df.columns)}"
          
          original_rows = len(df)
          
          # Apply filter
          if condition == "equals":
              filtered_df = df[df[column].astype(str) == value]
          elif condition == "contains":
              filtered_df = df[df[column].astype(str).str.contains(value, case=False, na=False)]
          elif condition == "greater_than":
              try:
                  numeric_value = float(value)
                  filtered_df = df[pd.to_numeric(df[column], errors='coerce') > numeric_value]
              except ValueError:
                  return f"Error: Cannot convert '{value}' to number for greater_than comparison"
          elif condition == "less_than":
              try:
                  numeric_value = float(value)
                  filtered_df = df[pd.to_numeric(df[column], errors='coerce') < numeric_value]
              except ValueError:
                  return f"Error: Cannot convert '{value}' to number for less_than comparison"
          else:
              return f"Error: Unknown condition '{condition}'. Use: equals, contains, greater_than, less_than"
          
          result = {
              "original_rows": original_rows,
              "filtered_rows": len(filtered_df),
              "filter_applied": f"{column} {condition} {value}"
          }
          
          # If output path is specified, save filtered data
          if output_path:
              output_extension = Path(output_path).suffix.lower()
              if output_extension == '.csv':
                  filtered_df.to_csv(output_path, index=False)
              elif output_extension == '.json':
                  filtered_df.to_json(output_path, orient='records', indent=2)
              elif output_extension in ['.xlsx', '.xls']:
                  filtered_df.to_excel(output_path, index=False)
              else:
                  # Default to CSV
                  filtered_df.to_csv(output_path, index=False)
              result["saved_to"] = output_path
          
          return json.dumps(result, indent=2)
          
      except Exception as e:
          return f"Error filtering data: {str(e)}\n{traceback.format_exc()}"

• src/visidata_mcp/server.py:323-323 (registration)

  The @mcp.tool() decorator that registers filter_data as an MCP tool

  @mcp.tool()