Add create-meta subcommand

metasyn/__main__.py

@@ -4,12 +4,15 @@
 import pathlib
 import pickle
 import sys
+from configparser import ConfigParser
 
 try:  # Python < 3.10 (backport)
     from importlib_metadata import entry_points, version
 except ImportError:
     from importlib.metadata import entry_points, version  # type: ignore [assignment]
 
+import polars as pl
+
 from metasyn import MetaFrame
 from metasyn.validation import create_schema
 
@@ -19,7 +22,8 @@
 Usage: metasyn [subcommand] [options]
 
 Available subcommands:
-    synthesize - generate synthetic data from a .json file
+    create-meta - generate a GMF (.json) file.
+    synthesize - generate synthetic data from a GMF (.json) file
     jsonschema - generate json schema from distribution providers
 
 Program information:
@@ -46,11 +50,72 @@ def main() -> None:
     elif subcommand == "schema":
         schema()
 
+    elif subcommand == "create-meta":
+        create_metadata()
+
     else:
         print(f"Invalid subcommand ({subcommand}). For help see metasyn --help")
         sys.exit(1)
 
 
+def _parse_config(config_fp):
+    config = ConfigParser()
+    config.read(config_fp)
+    spec = {}
+    for section in config.sections():
+        if section.startswith("var."):
+            new_dict = {}
+            for key, val in dict(config[section]).items():
+                try:
+                    new_dict[key] = config.getboolean(section, key)
+                except ValueError:
+                    pass
+                try:
+                    new_dict[key] = config.getfloat(section, key)
+                except ValueError:
+                    pass
+                try:
+                    new_dict[key] = config.getint(section, key)
+                except ValueError:
+                    pass
+                if key not in new_dict:
+                    new_dict[key] = val
+            spec[section[4:]] = new_dict
+    return spec
+
+
+def create_metadata():
+    """Program to create and export metadata from a DataFrame to a GMF file (.json)."""
+    parser = argparse.ArgumentParser(
+        prog="metasyn create-meta",
+        description="Create a Generative Metadata Format file from a CSV file.",
+    )
+    parser.add_argument(
+        "input",
+        help="input file; a CSV file that you want to synthesize later.",
+        type=pathlib.Path,
+    )
+    parser.add_argument(
+        "output",
+        help="output file: .json",
+        type=pathlib.Path,
+    )
+    parser.add_argument(
+        "--config",
+        help="Configuration file to specify distribution behavior.",
+        type=pathlib.Path,
+        default=None,
+    )
+    args, _ = parser.parse_known_args()
+    if args.config is not None:
+        spec = _parse_config(args.config)
+    else:
+        spec = {}
+    data_frame = pl.read_csv(args.input, try_parse_dates=True)
+    meta_frame = MetaFrame.fit_dataframe(data_frame, spec=spec)
+    meta_frame.export(args.output)
+
+
 def synthesize() -> None:
     """Program to generate synthetic data."""
     parser = argparse.ArgumentParser(