[SOLVED] How to annotate a Gadfly heatmap?

How to annotate a Gadfly heatmap?

Coming from Python I'm trying to reproduce this Seaborn plot in Julia using the Gadfly package. I've two questions:

How to annotate this heatmap with the actual values per cell without "duplicating" lines of code?
And how to modify the xticks to show all the year values from 1949 to 1960?

My code so far:

using DataFrames
using CSV
using Gadfly
using Compose
using ColorSchemes 

download("https://raw.githubusercontent.com/mwaskom/seaborn-data/master/flights.csv", "flights.csv");
flights = DataFrame(CSV.File("flights.csv"))
flights_unstacked = unstack(flights, :month, :year, :passengers)

set_default_plot_size(16cm, 12cm)

plot(
    flights, 
    x=:year, 
    y=:month, 
    color=:passengers, 
    Geom.rectbin, 
    Scale.ContinuousColorScale(palette -> get(ColorSchemes.magma, palette)),
    Guide.xticks(ticks=[minimum(flights.year):maximum(flights.year);]), 
    Theme(background_color = "white"),

    Guide.annotation(compose(context(), text(fill(1949, 12), 1:12, string.(flights_unstacked[:, "1949"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1950, 12), 1:12, string.(flights_unstacked[:, "1950"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1951, 12), 1:12, string.(flights_unstacked[:, "1951"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1952, 12), 1:12, string.(flights_unstacked[:, "1952"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1953, 12), 1:12, string.(flights_unstacked[:, "1953"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1954, 12), 1:12, string.(flights_unstacked[:, "1954"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1955, 12), 1:12, string.(flights_unstacked[:, "1955"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1956, 12), 1:12, string.(flights_unstacked[:, "1956"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1957, 12), 1:12, string.(flights_unstacked[:, "1957"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1958, 12), 1:12, string.(flights_unstacked[:, "1958"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1959, 12), 1:12, string.(flights_unstacked[:, "1959"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    Guide.annotation(compose(context(), text(fill(1960, 12), 1:12, string.(flights_unstacked[:, "1960"]), [hcenter], [vcenter]), fontsize(7pt), stroke("white"))), 
    )

Solution

The year xticks answer is to add

Guide.xticks(ticks=[minimum(flights.year):maximum(flights.year);]),

to the plot statement.

You then need a Guide.annotation() statement for the annotations. It needs some tuning to look the same as Seaborn's, but this does what you need:

Guide.annotation(
    compose(
        context(),
        text(
            flights.year,
            12:-1:1,
            string.(flights.passengers),
            [hcenter for x in flights.passengers],
        ),
        fontsize(2.5),
        stroke("white"),
    ),