# Animated Unicode Plots with Julia

I love Julia’s UnicodePlots.jl, a package for making pretty, colourful plots directly in the terminal. While playing around for Advent of Code I wrote a function to animate a sequence of Unicode plots. It’s not much, but I couldn’t find anything similar on Google so I thought I’d share.

The move_up helper function is the fiddly part; it moves the cursor to the start of where the plot begins so that a new plot can be printed right on top. After that I print the frames one after another, with a chosen delay, and finish by printin the final frame:

using UnicodePlots

function move_up(s::AbstractString)
move_up_n_lines(n) = "\u1b[\$(n)F"
# actually string_height - 1, but we're assuming cursor is on the last line
string_height = length(collect(eachmatch(r"\n", s)))
print(move_up_n_lines(string_height))
nothing
end

function animate(plots; frame_delay = 0)
print("\u001B[?25l") # hide cursor
for frame in frames[1:end-1]
print(frame)
sleep(frame_delay)
move_up(string(frame))
end
print(frames[end])
print("\u001B[?25h") # visible cursor
nothing
end


Now, to generate the example:

function makeplot(x::Integer)
lineplot(
[-1, 2, 3, 7],
[-1, floor(x / 2), 9, x],
title = "Example Plot",
name = "my line",
xlabel = "x",
ylabel = "y",
border = :dotted,
canvas = DotCanvas
)
end

frames = [makeplot(i) for i in vcat(1:9, range(9, 1, step = -1))]
animate(frames; frame_delay = 0.1)