From 18c6f061e3f2b49daf3819b5f2511c00303518fd Mon Sep 17 00:00:00 2001
From: LukasK13 <spam.lukas.klass@gmail.com>
Date: Tue, 14 Apr 2020 19:55:09 +0200
Subject: [PATCH] Grey body factory and lambda checker added

---
 esbo_etc/lib/helpers.py | 42 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/esbo_etc/lib/helpers.py b/esbo_etc/lib/helpers.py
index e17e97a..ed4cd80 100644
--- a/esbo_etc/lib/helpers.py
+++ b/esbo_etc/lib/helpers.py
@@ -1,6 +1,9 @@
 import logging
 import sys
 import traceback
+import astropy.units as u
+from astropy.modeling.models import BlackBody
+from typing import Union
 
 
 def error(msg: str, exit_: bool = True):
@@ -22,3 +25,42 @@ def error(msg: str, exit_: bool = True):
     if exit_:
         traceback.print_stack()
         sys.exit(1)
+
+
+@u.quantity_input(temp=[u.Kelvin, u.Celsius])
+def gb_factory(temp: u.Quantity, em: Union[int, float] = 1):
+    """
+    Factory for a grey body lambda-function.
+
+    Parameters
+    ----------
+    temp : Quantity in Kelvin / Celsius
+        The temperature fo the grey body.
+    em : Union[int, float]
+        Emissivity of the the grey body
+
+    Returns
+    -------
+    bb : Callable
+        The lambda function for the grey body.
+    """
+    bb = BlackBody(temperature=temp * u.K, scale=em * u.W / (u.m ** 2 * u.nm * u.sr))
+    return lambda wl: bb(wl)
+
+
+def isLambda(v: object):
+    """
+    Check if a object is of type lambda
+
+    Parameters
+    ----------
+    v : object
+        The object to check.
+
+    Returns
+    -------
+    res : bool
+        Result of the check
+    """
+    LAMBDA = lambda: 0
+    return isinstance(v, type(LAMBDA)) and v.__name__ == LAMBDA.__name__