half way there

metobs/data/filter.py

+"""Array filtering functions
+"""
+from numpy import ndarray, array, diff
+from numpy.ma import MaskedArray, masked_array
+
+__docformat__ = 'Epytext'
+__author__ = 'David Hoese'
+__version__ = '$Revision: 1.0 $'
+
+def filter_arr(arr, threshold, fill_value=None):
+    """Filter array arr of values that have a difference from the trend of
+    threshold.  If fill_value is None(default) then a numpy.ma.masked_array will
+    be returned with the filtered values being masked.
+
+    @param arr: array to be filtered
+    @type arr: array or list
+    @param threshold: allowable change between values
+    @type threshold: int or float
+    @param fill_value: Value to replace the filtered values with (ex. NaN)
+    @type fill_value: anything
+    """
+    if type.arr != ndarray or type.arr != MaskedArray:
+        if fill_value != None: arr = array(arr)
+        if fill_value == None: arr = masked_array(arr)
+
+    diff_arr = diff(arr, n=1)
+
+    if fill_value == None: arr = masked_where(diff_arr >= threshold, arr)
+
+    return arr
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