Use HipsSurveyProperties to write the properties file

hips/draw/healpix.py

@@ -1,8 +1,9 @@
 # Licensed under a 3-clause BSD style license - see LICENSE.rst
 from pathlib import Path
+from collections import OrderedDict
 import numpy as np
 from astropy_healpix import healpy as hp
-from ..tiles import HipsTile, HipsTileMeta
+from ..tiles import HipsTile, HipsTileMeta, HipsSurveyProperties
 from ..utils.healpix import hips_tile_healpix_ipix_array
 
 
@@ -76,12 +77,11 @@ def healpix_to_hips(hpx_data, tile_width, base_path, file_format='fits'):
         filename.parent.mkdir(exist_ok=True, parents=True)
         tile.write(filename=filename)
 
-    # Write a minimal property file
-    properties = f"""
-    hips_tile_format = {file_format}
-    hips_tile_width = {tile_width}
-    hips_frame = {tile.meta.frame}
-    """
 
-    with (base_path / 'properties').open('w') as f:
-        f.write(properties)
+    data = OrderedDict()
+    data['hips_tile_format'] = file_format
+    data['hips_tile_width'] = tile_width
+    data['hips_frame'] = tile.meta.frame
+
+    properties = HipsSurveyProperties(data=data)
+    properties.write(base_path / 'properties')

hips/draw/tests/test_healpix.py

@@ -32,3 +32,6 @@ def test_healpix_to_hips(tmpdir, file_format):
             data = np.array(Image.open(filename))
             data = data.T
         assert_allclose(val, data)
+
+    properties = (tmpdir / 'properties').read_text(encoding=None)
+    assert file_format in properties

hips/tiles/survey.py

@@ -2,6 +2,7 @@
 from collections import OrderedDict
 from io import StringIO
 from csv import DictWriter
+from pathlib import Path
 import urllib.request
 from typing import List, Union
 from astropy.table import Table
@@ -178,6 +179,29 @@ def tile_url(self, tile_meta: HipsTileMeta) -> str:
         """Tile URL on the server (str)."""
         return self.base_url + '/' + tile_meta.tile_default_url
 
+    def to_string(self):
+        """Convert properties to string"""
+        properties = ''
+        for key, value in self.data.items():
+            line = f'{key} = {value}\n'
+            properties += line
+
+        return properties
+
+    def write(self, path):
+        """
+        Write properties to text file.
+
+        Parameters
+        ----------
+        path : str or `~pathlib.Path`
+            Base path where to write the properties file.
+        """
+        text = self.to_string()
+        Path(path).write_text(text)
+
+
+
 
 class HipsSurveyPropertiesList:
     """HiPS survey properties list.