##Cell Statistics=name
##Select_directory=Folder
##statistic_name=string average
##Output_raster=Output raster
import glob, os
from PyQt4.QtCore import QFileInfo
from qgis.core import QgsRasterLayer, QgsRectangle

os.chdir(Select_directory)
raster_list = []
extent = QgsRectangle()
extent.setMinimal()

statistic_dic = {'average':0, 'count':1, 'median':2,'mode':3, 'minimum':4, 'min_raster':5,'maximum':6, 'max_raster':7, 'std':8, 'range':9}


for raster in glob.glob("*.tif"):
    fileInfo = QFileInfo(raster)
    baseName = fileInfo.baseName()
    rlayer = QgsRasterLayer(raster, baseName)
    # Combine raster layers to list
    raster_list .append(rlayer)
    # Combine raster extents
    extent.combineExtentWith(rlayer.extent())

# Get extent
xmin = extent.xMinimum()
xmax = extent.xMaximum()
ymin = extent.yMinimum()
ymax = extent.yMaximum()
# Run algorithm and set relevant parameters
processing.runalg("grass7:r.series",
                {"input":raster_list ,
                "-n":False,
                "method":statistic_dic[statistic_name],
                "range":'-10000000000,10000000000',
                "GRASS_REGION_PARAMETER":"%f,%f,%f,%f"% (xmin, xmax, ymin, ymax),
                "GRASS_REGION_CELLSIZE_PARAMETER":0,
                "output":Output_raster})