Issue/204/is qp file

src/qp/__init__.py

@@ -12,7 +12,7 @@
 from .scipy_pdfs import *
 from .packed_interp_pdf import *
 from .ensemble import Ensemble
-from .factory import instance, add_class, create, read, read_metadata, convert, concatenate, iterator, data_length, from_tables
+from .factory import instance, add_class, create, read, read_metadata, convert, concatenate, iterator, data_length, from_tables, is_qp_file
 from .lazy_modules import *
 
 from . import utils

src/qp/factory.py

@@ -158,6 +158,29 @@ def read_metadata(self, filename):
         tables = io.read(filename, NUMPY_DICT, keys=['meta'])
         return tables["meta"]
 
+    def is_qp_file(self, filename):
+        """Test if a file is a qp file
+
+        Parameters
+        ----------
+        filename : `str`
+            File to test
+
+        Returns
+        -------
+        value : bool
+            True if the file is a qp file
+        """
+        try:
+            # If this isn't a table-like file with a 'meta' table this will throw an exception
+            tables = io.readNative(filename, keys=['meta'])
+            # If the 'meta' tables doesn't have 'pdf_name' or it is empty this will throw an exception or fail
+            return len(tables['meta']['pdf_name']) > 0
+        except Exception as msg:
+            # Any exception means it isn't a qp file
+            print(f"This is not a qp file because {msg}")
+        return False
+
     def read(self, filename):
         """Read this ensemble from a file
 
@@ -343,3 +366,4 @@ def instance():
 concatenate = _FACTORY.concatenate
 data_length = _FACTORY.data_length
 from_tables = _FACTORY.from_tables
+is_qp_file = _FACTORY.is_qp_file

tests/qp/test_infrastructure.py

@@ -4,7 +4,7 @@
 import os
 import unittest
 import qp
-
+from qp.test_funcs import build_ensemble
 from qp import test_data
 
 
@@ -55,6 +55,14 @@ def test_get_val_or_default():
         test_dict.pop(None)
         assert qp.dict_utils.get_val_or_default(test_dict, 'nokey') is None
 
+    def test_is_qp_file(self):
+        fname = 'norm_ensemble.hdf5'
+        norm_test_data = qp.stats.norm_gen.test_data['norm']
+        ens_norm = build_ensemble(norm_test_data)
+        ens_norm.write_to(fname)
+        self.files.append(fname)
+        assert qp.instance().is_qp_file(fname)
+        assert not qp.instance().is_qp_file('test_pit.py')
 
 if __name__ == '__main__':
     unittest.main()