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I have a raster in .img format and i would trasform some values (Nan) into 0 with QGIS 2.14.3 (Windows). I've tried different ways but I didn't have results: 1- with raster --> conversion --> conversion format 2- operations with raster calculator (to replace non-zero values). With this operations, Nan values have been replaced by Nodata. After I have repeated the same operations but no data values haven't been replaced.