fix Gamma

Author: felixcheung

R/pkg/R/mllib_regression.R

@@ -106,8 +106,9 @@ setMethod("spark.glm", signature(data = "SparkDataFrame", formula = "formula"),
               weightCol <- ""
             }
 
+            # For known families, Gamma is upper-cased
             jobj <- callJStatic("org.apache.spark.ml.r.GeneralizedLinearRegressionWrapper",
-                                "fit", formula, data@sdf, family$family, family$link,
+                                "fit", formula, data@sdf, tolower(family$family), family$link,
                                 tol, as.integer(maxIter), as.character(weightCol), regParam)
             new("GeneralizedLinearRegressionModel", jobj = jobj)
           })