DataFrames.jl is loaded dynamically.

Since the package is only needed to implement wrappers around the actual functions, there's no immediate drawback of loading it dynamically; any user will only need the wrappers after loading DataFrames, too. Perfect use case for Requires.jl.

Project.toml

@@ -16,14 +16,15 @@ ImageMagick = "6218d12a-5da1-5696-b52f-db25d2ecc6d1"
 Images = "916415d5-f1e6-5110-898d-aaa5f9f070e0"
 IndirectArrays = "9b13fd28-a010-5f03-acff-a1bbcff69959"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
+Requires = "ae029012-a4dd-5104-9daa-d747884805df"
 StatsBase = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
 TikzPictures = "37f6aa50-8035-52d0-81c2-5a1d08754b2d"
 
 [compat]
-Contour = "0.5"
 ColorBrewer = "0.4"
-Colors = "0.12"
 ColorSchemes = "3.9"
+Colors = "0.12"
+Contour = "0.5"
 DataFrames = "0.21"
 Discretizers = "3.2"
 ImageMagick = "0.7.3, 1"

src/PGFPlots.jl

@@ -8,10 +8,15 @@ export pushPGFPlots, popPGFPlots
 import Colors: RGB
 import Contour: contours, levels
 
+using Requires
 using Discretizers
-using DataFrames
 using Printf
 
+# load dynamic dependencies
+function __init__()
+    @require DataFrames="a93c6f00-e57d-5684-b7b6-d8193f3e46c0" include("dataframes.jl")
+end
+
 mutable struct ErrorBars
     data::AbstractMatrix{Real}
     style
@@ -42,14 +47,6 @@ end
 include("colormaps.jl")
 include("plots.jl")
 
-Plots.Linear(df::DataFrame; x::Symbol=:x, y::Symbol=:y, kwargs...) = Plots.Linear(df[!,x], df[!,y]; kwargs...)
-Plots.Linear3(df::DataFrame; x::Symbol=:x, y::Symbol=:y, z::Symbol=:z, kwargs...) = Plots.Linear3(df[!,x], df[!,y], df[!,z]; kwargs...)
-Plots.Histogram(df::DataFrame; x::Symbol=:x, kwargs...) = Plots.Histogram(df[!,x]; kwargs...)
-Plots.Scatter(df::DataFrame; x::Symbol=:x, y::Symbol=:y, kwargs...) = Plots.Scatter(df[!,x], df[!,y]; kwargs...)
-Plots.Quiver(df::DataFrame; x::Symbol=:x, y::Symbol=:y, u::Symbol=:u, v::Symbol=:v, kwargs...) = Plots.Quiver(convert(Vector, df[!,x]), convert(Vector, df[!,y]), convert(Vector, df[!,u]), convert(Vector, df[!,v]); kwargs...)
-Plots.Histogram2(df::DataFrame; x::Symbol=:x, y::Symbol=:y, kwargs...) = Plots.Histogram2(convert(Vector, df[!,x]), convert(Vector, df[!,y]); kwargs...)
-Plots.Histogram2(df::DataFrame, edges_x::AbstractVector{C}, edges_y::AbstractVector{C}; x::Symbol=:x, y::Symbol=:y, kwargs...) where {C<:Real} = Plots.Histogram2(convert(Vector, df[!,x]), convert(Vector, df[!,y]), edges_x, edges_y; kwargs...)
-
 import TikzPictures: TikzPicture, PDF, TEX, TIKZ, SVG, save, LaTeXString, @L_str, @L_mstr
 
 _pgfplotsoptions = Any[""]

src/dataframes.jl

@@ -0,0 +1,22 @@
+using DataFrames
+
+Plots.Linear(df::DataFrame; x::Symbol=:x, y::Symbol=:y, kwargs...) =
+    Plots.Linear(df[!,x], df[!,y]; kwargs...)
+
+Plots.Linear3(df::DataFrame; x::Symbol=:x, y::Symbol=:y, z::Symbol=:z, kwargs...) =
+    Plots.Linear3(df[!,x], df[!,y], df[!,z]; kwargs...)
+
+Plots.Histogram(df::DataFrame; x::Symbol=:x, kwargs...) =
+    Plots.Histogram(df[!,x]; kwargs...)
+
+Plots.Scatter(df::DataFrame; x::Symbol=:x, y::Symbol=:y, kwargs...) =
+    Plots.Scatter(df[!,x], df[!,y]; kwargs...)
+
+Plots.Quiver(df::DataFrame; x::Symbol=:x, y::Symbol=:y, u::Symbol=:u, v::Symbol=:v, kwargs...) =
+    Plots.Quiver(convert(Vector, df[!,x]), convert(Vector, df[!,y]), convert(Vector, df[!,u]), convert(Vector, df[!,v]); kwargs...)
+
+Plots.Histogram2(df::DataFrame; x::Symbol=:x, y::Symbol=:y, kwargs...) =
+    Plots.Histogram2(convert(Vector, df[!,x]), convert(Vector, df[!,y]); kwargs...)
+
+Plots.Histogram2(df::DataFrame, edges_x::AbstractVector{C}, edges_y::AbstractVector{C}; x::Symbol=:x, y::Symbol=:y, kwargs...) where {C<:Real} =
+    Plots.Histogram2(convert(Vector, df[!,x]), convert(Vector, df[!,y]), edges_x, edges_y; kwargs...)