add press to altitude

modules/util/util.py

 import numpy as np
+from metpy.units import units
+from metpy.calc import thickness_hydrostatic
+
+
+class MyGenericException(Exception):
+    def __init__(self, message):
+        self.message = message
 
 
 def haversine_np(lon1, lat1, lon2, lat2):
@@ -53,3 +60,49 @@ def get_breaks(t, threshold):
     idxs = np.nonzero(d > threshold)
     return idxs
 
+
+def pressure_to_altitude(pres, temp, prof_pres, prof_temp, sfc_pres, sfc_temp, sfc_elev):
+    if not np.all(np.diff(prof_pres) > 0):
+        raise MyGenericException("target pressure profile must be monotonic increasing")
+
+    if pres < prof_pres[0]:
+        raise MyGenericException("target pressure less than top of pressure profile")
+
+    if temp is None:
+        temp = np.interp(pres, prof_pres, prof_temp)
+
+    i_top = np.argmax(np.extract(prof_pres <= pres, prof_pres)) + 1
+
+    pres_s = prof_pres.tolist()
+    temp_s = prof_temp.tolist()
+
+    pres_s = [pres] + pres_s[i_top:]
+    temp_s = [temp] + temp_s[i_top:]
+
+    prof_pres = np.array(pres_s)
+    prof_temp = np.array(temp_s)
+
+    i_bot = prof_pres.shape[0] - 1
+
+    if sfc_pres > prof_pres[i_bot]:
+        pres_s = pres_s + [sfc_pres]
+        temp_s = temp_s + [sfc_temp]
+    else:
+        idx = np.argmax(np.extract(prof_pres <= sfc_pres, prof_pres))
+        if sfc_temp is None:
+            sfc_temp = np.interp(sfc_pres, prof_pres, prof_temp)
+        pres_s = prof_pres.tolist()
+        temp_s = prof_temp.tolist()
+        pres_s = pres_s[0:idx] + [sfc_pres]
+        temp_s = temp_s[0:idx] + [sfc_temp]
+
+    prof_pres = np.array(pres_s)
+    prof_temp = np.array(temp_s)
+
+    prof_pres = prof_pres * units.hectopascal
+    prof_temp = prof_temp * units.kelvin
+    sfc_elev = sfc_elev * units.meter
+
+    z = thickness_hydrostatic(prof_pres, prof_temp) + sfc_elev
+
+    return z
\ No newline at end of file