median in ggraph heat map

[pspangler1]

I would like to illustrate median values in the ggraph heat map below instead of the default mean. 

Looking at GPL I do not see a similar option for median values? Does GPL have this ability?

GGRAPH 

  /GRAPHDATASET NAME="graphdataset" 

    VARIABLES=level2recode[LEVEL=nominal] cat_level_1[LEVEL=nominal] Price[LEVEL=scale] 

    MISSING=LISTWISE REPORTMISSING=NO 

  /GRAPHSPEC SOURCE=VIZTEMPLATE(NAME="Heat Map"[LOCATION=LOCAL] 

    MAPPING( "color"="Price"[DATASET="graphdataset"] "rows"="cat_level_1"[DATASET="graphdataset"] "columns"="level2recode"[DATASET="graphdataset"])) 

    VIZSTYLESHEET="Traditional"[LOCATION=LOCAL] 

    LABEL='HEAT MAP: Price-cat_level_1-level2recode' 

    DEFAULTTEMPLATE=NO.

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