make_r500_regions.py: split out functions "get_r500()" and "get_center()"

1 files changed, 53 insertions, 23 deletions

diff --git a/make_r500_regions.py b/make_r500_regions.py
index d7e15cf..cc0c0a2 100755
--- a/make_r500_regions.py
+++ b/make_r500_regions.py
@@ -6,9 +6,12 @@
 # in order to visualize the FoV coverage of the observations.
 #
 # Aaron LI
-# 2016-04-15
+# Created: 2016-04-15
+# Updated: 2016-04-28
 #
-# ChangeLog:
+# Changelog:
+# 2016-04-28:
+#   * Add functions "get_r500()" and "get_center()" for code reuse
 # 2016-04-16:
 #   * Fix R500 unit (convert from kpc to Chandra ACIS pixel)
 #
@@ -21,6 +24,50 @@ import json
 import argparse
 
 
+def get_r500(info):
+    """
+    Get the R500 value (in unit pixel and kpc), as well as the value of
+    "kpc_per_pix"
+    """
+    if isinstance(info, str):
+        json_str = open(info_json).read().rstrip().rstrip(",")
+        info = json.loads(json_str)
+
+    if "R500 (kpc)" in info.keys():
+        # LWT's
+        r500_kpc = float(info["R500 (kpc)"])
+    elif "R500" in info.keys():
+        # ZZH's
+        r500_kpc = float(info["R500"])
+    else:
+        raise ValueError("Cannot get R500")
+
+    # Convert kpc to Chandra ACIS pixel
+    rmax_sbp_pix = float(info["Rmax_SBP (pixel)"])
+    rmax_sbp_kpc = float(info["Rmax_SBP (kpc)"])
+    kpc_per_pix  = rmax_sbp_kpc / rmax_sbp_pix
+    r500_pix     = r500_kpc / kpc_per_pix
+
+    results = {
+            "r500_kpc":    r500_kpc,
+            "r500_pix":    r500_pix,
+            "kpc_per_pix": kpc_per_pix,
+    }
+    return results
+
+
+def get_center(regfile):
+    """
+    Get the center coordinate from the given region file
+    """
+    regions = open(regfile).readlines()
+    regions = list(filter(lambda x: re.match(r"^(circle|annulus|pie).*",
+                                             x, re.I),
+                          regions))
+    xc, yc = map(float, re.split(r"[(,)]", regions[0])[1:3])
+    return (xc, yc)
+
+
 def frange(x, y, step):
     while x < y:
         yield x
@@ -45,30 +92,13 @@ def main():
     if args.json:
         info_json = args.json
 
-    json_str = open(info_json).read().rstrip().rstrip(",")
-    info = json.loads(json_str)
-
-    if "R500 (kpc)" in info.keys():
-        # lwt's
-        r500_kpc = float(info["R500 (kpc)"])
-    elif "R500" in info.keys():
-        # zzh's
-        r500_kpc = float(info["R500"])
-    else:
-        raise ValueError("Cannot get R500 from INFO.json")
-
-    # Convert kpc to Chandra ACIS pixel
-    rmax_sbp_pix = float(info["Rmax_SBP (pixel)"])
-    rmax_sbp_kpc = float(info["Rmax_SBP (kpc)"])
-    r500_pix = r500_kpc / rmax_sbp_kpc * rmax_sbp_pix
+    r500 = get_r500(info_json)
+    r500_kpc = r500["r500_kpc"]
+    r500_pix = r500["r500_pix"]
     print("R500: %.2f (kpc), %.2f (pixel)" % (r500_kpc, r500_pix))
 
     # get center coordinate
-    regions = open(args.regin).readlines()
-    regions = list(filter(lambda x: re.match(r"^(circle|annulus|pie).*",
-                                             x, re.I),
-                          regions))
-    xc, yc = re.split(r"[(,)]", regions[0])[1:3]
+    xc, yc = get_center(args.regin)
 
     # output region
     r500_regions = [