added max_scaling_factor for linear_scaling (*) and delta_method (*) to avoid unrealistic results in some cases

Author: btschwertfeger

README.md

@@ -1,4 +1,4 @@
-# Bias-Adjustment-Python
+# Bias adjustment/correction procedures for climatic reasearch
 
 <div style="text-align: center">
 
@@ -9,7 +9,7 @@
 
 </div>
 
-Collection of different scale- and distribution-based bias adjustment techniques for climatic research. (see `examples.ipynb` for help)
+Collection of different scale- and distribution-based bias adjustment techniques for climatic research (see `examples.ipynb` for help).
 
 Bias adjustment procedures in Python are very slow, so they should not be used on large data sets.
 A C++ implementation that works way faster can be found [here](https://github.com/btschwertfeger/Bias-Adjustment-Cpp).
@@ -88,6 +88,11 @@ qdm_result = cm.adjust_3d( # 3d = 2 spatial and 1 time dimension
 # ratio based variables like precipitation)
 ```
 
+Notes:
+
+- When using the `adjust_3d` method you have to specify the method by name.
+- For the multiplicative linear scaling and delta method is a maximum scaling factor of 10 set. This can be changed by the `max_scaling_factor` parameter.
+
 ---
 
 ## Examples (see repository on [GitHub](https://github.com/btschwertfeger/Bias-Adjustment-Python))

cmethods/CMethods.py

@@ -54,6 +54,8 @@ def __init__(self, method: str, available_methods: list):
     ADDITIVE = ['+', 'add']
     MULTIPLICATIVE = ['*', 'mult']
 
+    MAX_SCALING_FACTOR = 10
+
     def __init__(self):
         pass
 
@@ -289,7 +291,14 @@ def linear_scaling(cls,
         if group != None: return cls.grouped_correction(method='linear_scaling', obs=obs, simh=simh, simp=simp, group=group, kind=kind, **kwargs)
         else:
             if kind in cls.ADDITIVE: return np.array(simp) + (np.nanmean(obs) - np.nanmean(simh)) # Eq. 1
-            elif kind in cls.MULTIPLICATIVE: return np.array(simp) * (np.nanmean(obs) / np.nanmean(simh)) # Eq. 2
+            elif kind in cls.MULTIPLICATIVE: 
+                scaling_factor = (np.nanmean(obs) / np.nanmean(simh))
+                if scaling_factor > 0 and scaling_factor > abs(kwargs.get('max_scaling_factor', cls.MAX_SCALING_FACTOR)):
+                    return np.array(simp) * abs(kwargs.get('max_scaling_factor', cls.MAX_SCALING_FACTOR))
+                elif scaling_factor < 0 and scaling_factor < -abs(kwargs.get('max_scaling_factor', cls.MAX_SCALING_FACTOR)):
+                    return np.array(simp) * -abs(kwargs.get('max_scaling_factor', cls.MAX_SCALING_FACTOR))
+                else: 
+                    return np.array(simp) * scaling_factor # Eq. 2
             else: raise ValueError('Scaling type invalid. Valid options for param kind: "+" and "*"')
 
     # ? -----========= V A R I A N C E - S C A L I N G =========------
@@ -404,7 +413,14 @@ def delta_method(cls,
         if group != None: return cls.grouped_correction(method='delta_method', obs=obs, simh=simh, simp=simp, group=group, kind=kind, **kwargs)
         else:
             if kind in cls.ADDITIVE: return np.array(obs) + (np.nanmean(simp) - np.nanmean(simh))     # Eq. 1
-            elif kind in cls.MULTIPLICATIVE: return np.array(obs) * (np.nanmean(simp) / np.nanmean(simh))   # Eq. 2
+            elif kind in cls.MULTIPLICATIVE: 
+                scaling_factor = (np.nanmean(simp) / np.nanmean(simh))  
+                if scaling_factor > 0 and scaling_factor > abs(kwargs.get('max_scaling_factor', cls.MAX_SCALING_FACTOR)):
+                    return np.array(obs) * abs(kwargs.get('max_scaling_factor', cls.MAX_SCALING_FACTOR))
+                elif scaling_factor < 0 and scaling_factor < -abs(kwargs.get('max_scaling_factor', cls.MAX_SCALING_FACTOR)):
+                    return np.array(obs) * -abs(kwargs.get('max_scaling_factor', cls.MAX_SCALING_FACTOR))
+                else: 
+                    return np.array(obs) * scaling_factor # Eq. 2
             else: raise ValueError(f'{kind} not implemented! Use "+" or "*" instead.')
 
 

cmethods/__version__.py

@@ -1,2 +1,2 @@
-VERSION = (0,5,3)
+VERSION = (0,5,4)
 __version__ = '.'.join(map(str, VERSION))

cmethods/tests/testing.py

@@ -8,6 +8,10 @@
 sys.path.append('../../')
 from cmethods.CMethods import CMethods
 
+if True: # local space
+    import cmethods
+    print(cmethods.__file__)
+
 formatter = logging.Formatter(
         fmt='%(asctime)s %(module)s,line: %(lineno)d %(levelname)8s | %(message)s',
         datefmt='%Y-%m-%d %H:%M:%S' # %I:%M:%S %p AM|PM format