include absolute bias
diff --git a/ocw/metrics.py b/ocw/metrics.py
index 3a6477e..b266012 100644
--- a/ocw/metrics.py
+++ b/ocw/metrics.py
@@ -281,6 +281,29 @@
return ma.average(bias, axis=0)
else:
return bias
+
+
+def calc_absbias(target_array, reference_array, average_over_time=False):
+ ''' Calculate absolute difference between two arrays
+
+ :param target_array: an array to be evaluated, as model output
+ :type target_array: :class:'numpy.ma.core.MaskedArray'
+
+ :param reference_array: an array of reference dataset
+ :type reference_array: :class:'numpy.ma.core.MaskedArray'
+
+ :param average_over_time: if True, calculated bias is averaged for the axis=0
+ :type average_over_time: 'bool'
+
+ :returns: Absolute Biases array of the target dataset
+ :rtype: :class:'numpy.ma.core.MaskedArray'
+ '''
+
+ bias = abs(target_array - reference_array)
+ if average_over_time:
+ return ma.average(bias, axis=0)
+ else:
+ return bias
def calc_stddev(array, axis=None):
