Pulling Range data from head instead of the calculated Range

Is there a way to select the range given by the meta-data for my scaler point array in vtk instead of pulling the calculated one from dataarray.getRange()? In another word how can I find the min and max of my dataset while ignoring the no data value? An example would be, my data set contain -100 as my no data value and my actual data values are from -10 to 10 but it can vary depending on the file given. Is there a way for me to find the min and the max of the dataset while ignoring -100.