Enhancements to data sampler

tools/statvar_importer/data_sampler.py

@@ -54,6 +54,14 @@
 flags.DEFINE_integer(
     'sampler_rows_per_key', 5,
     'The maximum number of rows to select for each unique value found.')
+flags.DEFINE_integer(
+    'sampler_uniques_per_column', 10,
+    'The maximum number of unique values to track per column. '
+    'If 0 or -1, all unique values are tracked.')
+flags.DEFINE_boolean(
+    'sampler_exhaustive', False,
+    'If True, sets sampler_output_rows and sampler_uniques_per_column to '
+    'infinity, and sampler_rows_per_key to 1, to capture every unique value.')
 flags.DEFINE_float(
     'sampler_rate', -1,
     'The sampling rate for random row selection (e.g., 0.1 for 10%).')
@@ -65,6 +73,11 @@
 flags.DEFINE_string(
     'sampler_unique_columns', '',
     'A comma-separated list of column names to use for selecting unique rows.')
+flags.DEFINE_list(
+    'sampler_column_keys', [],
+    'A list of "column:file" pairs containing values that MUST be included '
+    'in the sample if they appear in the input data. '
+    'Example: "variableMeasured:prominent_svs.txt"')
 flags.DEFINE_string('sampler_input_delimiter', ',',
                     'The delimiter used in the input CSV file.')
 flags.DEFINE_string('sampler_input_encoding', 'UTF8',
@@ -75,6 +88,7 @@
 _FLAGS = flags.FLAGS
 
 import file_util
+import mcf_file_util
 
 from config_map import ConfigMap
 from counters import Counters
@@ -103,27 +117,37 @@ def __init__(
         self,
         config_dict: dict = None,
         counters: Counters = None,
+        column_include_values: dict = None,
     ):
         """Initializes the DataSampler object.
 
         Args:
             config_dict: A dictionary of configuration parameters.
             counters: A Counters object for tracking statistics.
+            column_include_values: a dictionary of column-name to set of values
+              in the column to be included in the sample
         """
         self._config = ConfigMap(config_dict=get_default_config())
         if config_dict:
             self._config.add_configs(config_dict)
         self._counters = counters if counters is not None else Counters()
+        self._column_include_values = column_include_values
         self.reset()
 
     def reset(self) -> None:
         """Resets the state of the DataSampler.
 
         This method resets the internal state of the DataSampler, including the
-        counts of unique column values and the number of selected rows. This is
-        useful when you want to reuse the same DataSampler instance for sampling
-        multiple files.
+        counts of unique column values and the number of selected rows. If
+        sampler_exhaustive is set in the configuration, it applies overrides
+        to other configuration parameters to capture all unique values.
         """
+        if self._config.get('sampler_exhaustive'):
+            # Exhaustive mode overrides limits to capture all unique values.
+            self._config.set_config('sampler_output_rows', -1)
+            self._config.set_config('sampler_uniques_per_column', -1)
+            self._config.set_config('sampler_rows_per_key', 1)
+
         # Dictionary of unique values: count per column
         self._column_counts = {}
         # Dictionary of column index: list of header strings
@@ -144,6 +168,16 @@ def reset(self) -> None:
                 if col.strip()
             ]
 
+        # Must include values: dict of column_name -> set of values
+        self._must_include_values = load_column_keys(
+            self._config.get('sampler_column_keys', []))
+        if self._column_include_values:
+            for col, vals in self._column_include_values.items():
+                self._must_include_values.setdefault(col, set()).update(vals)
+
+        # Map of column index -> set of values
+        self._must_include_indices = {}
+
     def __del__(self) -> None:
         """Logs the column headers and counts upon object deletion."""
         logging.log(2, f'Sampler column headers: {self._column_headers}')
@@ -179,22 +213,35 @@ def _get_column_count(self, column_index: int, value: str) -> int:
             return 0
         return col_values.get(value, 0)
 
-    def _should_track_column(self, column_index: int) -> bool:
-        """Determines if a column should be tracked for unique values.
+    def _is_unique_column(self, column_index: int) -> bool:
+        """Determines if a column is specified for unique value sampling.
 
         Args:
             column_index: The index of the column.
 
         Returns:
-            True if the column should be tracked (either no unique columns
-            specified or this column is in the unique columns list).
+            True if the column should be sampled for unique values.
         """
         if not self._unique_column_names:
-            # No specific columns specified, track all
+            # No specific columns specified, track all for unique sampling
             return True
         # Check if this column is in our unique columns
         return column_index in self._unique_column_indices.values()
 
+    def _should_track_column(self, column_index: int) -> bool:
+        """Determines if a column should be tracked for counts.
+
+        Args:
+            column_index: The index of the column.
+
+        Returns:
+            True if the column should be tracked for unique values or is a
+            must-include column.
+        """
+        if self._is_unique_column(column_index):
+            return True
+        return column_index in self._must_include_indices
+
     def _process_header_row(self, row: list[str]) -> None:
         """Process a header row to build column name to index mapping.
 
@@ -206,15 +253,27 @@ def _process_header_row(self, row: list[str]) -> None:
         Args:
             row: A header row containing column names.
         """
-        if not self._unique_column_names:
-            return
-
         for index, column_name in enumerate(row):
-            if column_name in self._unique_column_names:
+            if self._unique_column_names and column_name in self._unique_column_names:
                 self._unique_column_indices[column_name] = index
                 logging.level_debug() and logging.debug(
                     f'Mapped unique column "{column_name}" to index {index}')
 
+            if self._must_include_values and column_name in self._must_include_values:
+                self._must_include_indices[index] = self._must_include_values[
+                    column_name]
+                logging.info(
+                    f'Mapped must-include column "{column_name}" to index {index}'
+                )
+
+    def _is_must_include(self, column_index: int, value: str) -> bool:
+        """Checks if a column value is in the must-include list."""
+        if column_index not in self._must_include_indices:
+            return False
+        # Normalize the input value before checking against the set
+        return mcf_file_util.strip_namespace(
+            value) in self._must_include_indices[column_index]
+
     def _add_column_header(self, column_index: int, value: str) -> str:
         """Adds the first non-empty value of a column as its header.
 
@@ -282,13 +341,26 @@ def select_row(self, row: list[str], sample_rate: float = -1) -> bool:
             # Too many rows already selected. Drop it.
             return False
         max_count = self._config.get('sampler_rows_per_key', 3)
+        if max_count <= 0:
+            max_count = sys.maxsize
         max_uniques_per_col = self._config.get('sampler_uniques_per_column', 10)
+        if max_uniques_per_col <= 0:
+            max_uniques_per_col = sys.maxsize
+
         for index in range(len(row)):
-            # Skip columns not in unique_columns list
-            if not self._should_track_column(index):
-                continue
             value = row[index]
             value_count = self._get_column_count(index, value)
+
+            # Rule 1: Always include if it's a must-include value and
+            # we haven't reached per-key limit.
+            if value_count < max_count and self._is_must_include(index, value):
+                self._counters.add_counter('sampler-selected-must-include', 1)
+                return True
+
+            # Skip columns not in unique_columns list for general unique sampling
+            if not self._is_unique_column(index):
+                continue
+
             if value_count == 0 or value_count < max_count:
                 # This is a new value for this column.
                 col_counts = self._column_counts.get(index, {})
@@ -301,7 +373,7 @@ def select_row(self, row: list[str], sample_rate: float = -1) -> bool:
         # No new unique value for the row.
         # Check random sampler.
         if sample_rate < 0:
-            sample_rate = self._config.get('sampler_rate')
+            sample_rate = self._config.get('sampler_rate', -1)
         if random.random() <= sample_rate:
             self._counters.add_counter('sampler-sampled-rows', 1)
             return True
@@ -390,6 +462,7 @@ def sample_csv_file(self, input_file: str, output_file: str = '') -> str:
                         # Process and write header rows from the first input file.
                         if row_index <= header_rows and input_index == 0:
                             self._process_header_row(row)
+                            self._add_row_counts(row)
                             csv_writer.writerow(row)
                             self._counters.add_counter('sampler-header-rows', 1)
                             # After processing all header rows, validate that all
@@ -425,9 +498,40 @@ def sample_csv_file(self, input_file: str, output_file: str = '') -> str:
         return output_file
 
 
+def load_column_keys(column_keys: list) -> dict:
+    """Returns a dictionary of column name to set of keys loaded from a file.
+    The set of keys for a column are used as filter when sampling.
+
+    Args:
+      column_keys: comma separated list of column_name:<csv file> with
+        first column as the keys to be loaded.
+
+    Returns:
+      dictionary of column name to a set of keys for that column
+        { <column-name1>: { key1, key2, ...}, <column-name2>: { k1, k2...} ...}
+    """
+    column_map = {}
+    if not isinstance(column_keys, list):
+        column_keys = column_keys.split(',')
+
+    for col_file in column_keys:
+        column_name, file_name = col_file.split(':', 1)
+        if not file_name:
+            logging.error(f'No file for column {column_name} in {column_keys}')
+            continue
+
+        col_items = file_util.file_load_csv_dict(file_name)
+        column_map[column_name] = set(col_items.keys())
+        logging.info(
+            f'Loaded {len(col_items)} for column {column_name} from {file_name}'
+        )
+    return column_map
+
+
 def sample_csv_file(input_file: str,
                     output_file: str = '',
-                    config: dict = None) -> str:
+                    config: dict = None,
+                    counters: Counters = None) -> str:
     """Samples a CSV file and returns the path to the sampled file.
 
     This function provides a convenient way to sample a CSV file with a single
@@ -443,6 +547,8 @@ def sample_csv_file(input_file: str,
           - sampler_output_rows: The maximum number of rows to include in the
             sample.
           - sampler_rate: The sampling rate to use for random selection.
+          - sampler_exhaustive: If True, overrides limits to capture all unique
+            values.
           - header_rows: The number of header rows to copy from the input file
             and search for sampler_unique_columns. Increase this if column names
             appear in later header rows (e.g., after a title row).
@@ -455,6 +561,7 @@ def sample_csv_file(input_file: str,
           - input_delimiter: The delimiter used in the input file.
           - output_delimiter: The delimiter to use in the output file.
           - input_encoding: The encoding of the input file.
+        counters: optional Counters object to get counts of sampling.
 
     Returns:
         The path to the output file with the sampled rows.
@@ -484,7 +591,7 @@ def sample_csv_file(input_file: str,
     """
     if config is None:
         config = {}
-    data_sampler = DataSampler(config_dict=config)
+    data_sampler = DataSampler(config_dict=config, counters=counters)
     return data_sampler.sample_csv_file(input_file, output_file)
 
 
@@ -500,23 +607,31 @@ def get_default_config() -> dict:
     # Use default values of flags for tests
     if not _FLAGS.is_parsed():
         _FLAGS.mark_as_parsed()
-    return {
+
+    config = {
         'sampler_rate': _FLAGS.sampler_rate,
         'sampler_input': _FLAGS.sampler_input,
         'sampler_output': _FLAGS.sampler_output,
         'sampler_output_rows': _FLAGS.sampler_output_rows,
         'header_rows': _FLAGS.sampler_header_rows,
         'sampler_rows_per_key': _FLAGS.sampler_rows_per_key,
+        'sampler_uniques_per_column': _FLAGS.sampler_uniques_per_column,
         'sampler_column_regex': _FLAGS.sampler_column_regex,
         'sampler_unique_columns': _FLAGS.sampler_unique_columns,
+        'sampler_column_keys': _FLAGS.sampler_column_keys,
         'input_delimiter': _FLAGS.sampler_input_delimiter,
         'output_delimiter': _FLAGS.sampler_output_delimiter,
         'input_encoding': _FLAGS.sampler_input_encoding,
+        'sampler_exhaustive': _FLAGS.sampler_exhaustive,
     }
 
+    return config
+
 
 def main(_):
-    sample_csv_file(_FLAGS.sampler_input, _FLAGS.sampler_output)
+    counters = Counters()
+    sample_csv_file(_FLAGS.sampler_input, _FLAGS.sampler_output, counters=counters)
+    counters.print_counters()
 
 
 if __name__ == '__main__':