using DataFrames, FreqTables, NamedArrays

using Plots
gr(size=(400, 300)); # as you like



# Heatmap difinition for pivot
Plots.heatmap(pivot::NamedArray)= heatmap(names(pivot)..., pivot.array')



df = DataFrame(Location = ["NY", "SF", "NY", "NY", "SF", "SF", "TX", "TX", "TX", "DC", "DC", "DC"],
               Class = ["M","M","H","L","L","H", "H","L","M","M","H","L"],
               Score = rand(12))

pivot = freqtable(df, :Location, :Class, weights=df.Score)

heatmap(pivot)