From e42cf80c7fecbfe1aab65b1b8af692a04b640451 Mon Sep 17 00:00:00 2001
From: dr-guangtou <dr.guangtou@gmail.com>
Date: Fri, 31 Aug 2018 17:00:38 -0700
Subject: [PATCH] #10 Add _find_sfd_map() function

---
 kungpao/extinction.py | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/kungpao/extinction.py b/kungpao/extinction.py
index ec1350e..0b6a67a 100644
--- a/kungpao/extinction.py
+++ b/kungpao/extinction.py
@@ -2,12 +2,35 @@
 
 from __future__ import print_function, absolute_import, division
 
+import subprocess
+
 from astropy.coordinates import SkyCoord
 
 
 __all__ = ['radec_extinction']
 
 
+def _find_sfd_maps(north='SFD_dust_4096_ngp.fits',
+                   south='SFD_dust_4096_sgp.fits', index=0):
+    """Use locate command to find the SFD files."""
+    north_map = subprocess.check_output(
+        "locate %s" % north, shell=True).splitlines()
+    south_map = subprocess.check_output(
+        "locate %s" % south, shell=True).splitlines()
+
+    if north_map:
+        north_file = north_map[index].decode('utf-8')
+    else:
+        north_file = None
+
+    if south_map:
+        south_file = south_map[index].decode('utf-8')
+    else:
+        south_file = None
+
+    return north_file, south_file
+
+
 def radec_extinction(ra, dec, a_lambda=1.0):
     """Estimate the Galactic extinction for HSC filters.