fix stuff

Don't run gnuplot process connected to stdout

.travis.yml

@@ -6,15 +6,15 @@ os:
 #  - osx
 
 julia:
-  - 1.2
-  - nightly
+  - 1.5
+#  - nightly
 
 notifications:
   email: false
 
-matrix:
-  allow_failures:
-    - julia: nightly
+#matrix:
+#  allow_failures:
+#    - julia: nightly
 
 addons:
   apt:

ChangeLog.md

@@ -1,6 +1,38 @@
-# Version 1.3.0 (released on: Apr. 28, 2020)
+# Version 1.4.1 (released on: )
+- New features:
+	* Implicit recipes can now returns a `Vector{PlotElement}`;
+
+	* Allow using single quotes in output file names (#52);
+
+	* New function: `palette_levels()` can be used to modify palette levels before passing them to gnuplot;
+
+- Bugfix:
+	* Fixed `BoundsErrors` in `hist()` (#49);
+
+	* Fixed problem when generating documentation (#51);
+
+
+# Version 1.4.0 (released on: May 5, 2021)
+- New features:
+    * Missing values are accepted if the input arrays have `eltype <:
+      AbstractFloat`;
+
+    * Missing values are also accepted in calls to `hist`;
+
+	* VSCode and Pluto sessions are now properly handled (#35 and #43);
+
+- Bugfix:
+	* Multiplot were not displayed in Jupyter (#25);
+
+	* `gpvars()` fails if gnuplot character encoding is utf8
+      (#24);
+
+
+# Version 1.3.0 (released on: Apr. 29, 2020)
 
 - New features:
+    * The new `dgrid3d()` allows to interpolate scattered 2D data on a
+       2D regular grid;
 
     * The `Options` structure features a new `mime` field containing a
       dictionary to map a MIME type to gnuplot terminals;

Project.toml

@@ -1,6 +1,6 @@
 name = "Gnuplot"
 uuid = "dc211083-a33a-5b79-959f-2ff34033469d"
-version = "1.3.0"
+version = "1.4.1"
 
 [deps]
 ColorSchemes = "35d6a980-a343-548e-a6ea-1d62b119f2f4"
@@ -14,11 +14,11 @@ StructC14N = "d2514e9c-36c4-5b8e-97e2-51e7675c221c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
-ColorSchemes = "^3.5"
-ColorTypes = "^0.10"
+ColorSchemes = "^3.12"
+ColorTypes = "^0.11"
 Colors = "^0.12"
-DataStructures = "^0.17"
+DataStructures = "^0.18"
 ReplMaker = "^0.2"
 StatsBase = "^0.33"
 StructC14N = "^0.3"
-julia = "^1.2"
+julia = "^1.6"

README.md

@@ -3,10 +3,10 @@
 
 [![Build Status](https://travis-ci.org/gcalderone/Gnuplot.jl.svg?branch=master)](https://travis-ci.org/gcalderone/Gnuplot.jl)
 [![License](http://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat)](LICENSE.md)
-[![DocumentationStatus](https://img.shields.io/badge/docs-stable-blue.svg?style=flat)](https://gcalderone.github.io/Gnuplot.jl/v1.3.0/)
+[![DocumentationStatus](https://img.shields.io/badge/docs-stable-blue.svg?style=flat)](https://gcalderone.github.io/Gnuplot.jl/v1.4.0/index.html)
 
 
-**Gnuplot.jl** is a simple package able to send both data and commands from Julia to an underlying [gnuplot](http://gnuplot.sourceforge.net/) process.  Its main purpose it to provide a fast and powerful data visualization framework, using an extremely concise Julia syntax.
+**Gnuplot.jl** is a simple package able to send both data and commands from Julia to an underlying [gnuplot](http://gnuplot.sourceforge.net/) process.  Its main purpose it to provide a fast and powerful data visualization framework, using an extremely concise Julia syntax. It also has automatic display of plots in Jupyter, Juno and VS Code.
 
 
 ## Installation
@@ -21,9 +21,9 @@ You may check the installed **Gnuplot.jl** version with:
 ```julia
 ]st Gnuplot
 ```
-If the displayed version is not v1.3.0 you are probably having a dependency conflict. In this case try forcing installation of the latest version with:
+If the displayed version is not v1.4.0 you are probably having a dependency conflict. In this case try forcing installation of the latest version with:
 ```julia
-]add Gnuplot@1.3.0
+]add Gnuplot@1.4.0
 ```
 and check which package is causing the conflict.
 
@@ -37,7 +37,7 @@ test_terminal()
 
 
 ## Quick start
-The following examples are supposed to be self-explaining.  See [documentation](https://gcalderone.github.io/Gnuplot.jl/v1.3.0/) for further informations.
+The following examples are supposed to be self-explaining.  See [documentation](https://gcalderone.github.io/Gnuplot.jl/v1.4.0/) for further informations.
 
 ### A simple parabola
 ```julia

docs/src/api.md

@@ -21,6 +21,7 @@ gpvars
 hist
 linetypes
 palette
+palette_levels
 palette_names
 recipe
 save

docs/src/basic.md

@@ -210,6 +210,16 @@ saveas("basic008a") # hide
 ```
 ![](assets/basic008a.png)
 
+The palette levels may be easily stretched by using the [`palette_levels()`](@ref) and modifying the numeric levels, e.g.:
+```@example abc
+x = 0:0.1:10pi
+v, l, n = palette_levels(:viridis)
+@gsp palette(v.^0.25, l, n) cbr=[-1,1].*30 :-
+@gsp :-  x  x.*sin.(x)  x.*cos.(x)  x./20  "w p pt 7 ps var lc pal"
+saveas("basic008b") # hide
+```
+![](assets/basic008b.png)
+
 The list of all available palette can be retrieved with [`palette_names()`](@ref):
 ```@repl abc
 palette_names()

docs/src/install.md

@@ -19,11 +19,11 @@ Check **Gnuplot.jl** version with:
 ```julia-repl
 julia> ]st Gnuplot
 Status `~/.julia/environments/v1.4/Project.toml`
-  [dc211083] Gnuplot v1.3.0
+  [dc211083] Gnuplot v1.4.1
 ```
-If the displayed version is not `v1.3.0` you are probably having a dependency conflict.  In this case try forcing installation of the latest version with:
+If the displayed version is not `v1.4.1` you are probably having a dependency conflict.  In this case try forcing installation of the latest version with:
 ```julia-repl
-julia> ]add Gnuplot@1.3.0
+julia> ]add Gnuplot@1.4.1
 ```
 and check which package is causing the conflict.
 

docs/src/options.md

@@ -70,12 +70,11 @@ Each line reports the package name (`GNUPLOT`), the session name (`default`), th
 
 ## Package initialization
 
-If you use **Gnuplot.jl** frequently you may find convenient to collect all the package settings ([Options](@ref)) in a single place, to quickly recall them in a Julia session.  A possibility is to put the following code in the `~/.julia/config/startup.jl` initialization file (further info [here](https://docs.julialang.org/en/v1/stdlib/REPL/)):
+If you use **Gnuplot.jl** frequently you may find convenient to automatically apply the package settings ([Options](@ref)) whenever the package is loaded.  A possibility is to use [Requires.jl](https://github.com/JuliaPackaging/Requires.jl) and put the following code in the `~/.julia/config/startup.jl` initialization file (further info [here](https://docs.julialang.org/en/v1/stdlib/REPL/)):
 ```julia
-macro gnuplotrc()
-    return :(
-        using Gnuplot;
-
+using Requires
+@require Gnuplot="dc211083-a33a-5b79-959f-2ff34033469d" begin
+        @info "Custom Gnuplot initialization"
         # Uncomment the following if you don't have the gnuplot
         # executable installed on your platform:
         #Gnuplot.options.dry = true;
@@ -103,17 +102,13 @@ macro gnuplotrc()
 
         # Set the default linetypes
         empty!(Gnuplot.options.init);
-        push!(Gnuplot.options.init, linetypes(:Set1_5, lw=1.5, ps=1.5));
+        push!(Gnuplot.options.init, Gnuplot.linetypes(:Set1_5, lw=1.5, ps=1.5));
 
         # Initialize the gnuplot REPL using the provided `start_key`.
         if Gnuplot.options.gpviewer;
             Gnuplot.repl_init(start_key='>');
         end;
-    )
 end
 ```
-At the Julia prompt you may load the package and the associated settings by typing:
-```julia
-julia> @gnuplotrc
-```
-and you're ready to go.
+
+The above code will be automatically when you first load the package with `using Gnuplot`.

docs/src/recipes.md

@@ -125,7 +125,7 @@ end
 with only one mandatory argument.  In order to exploit the optional keyword we can explicitly invoke the recipe as follows:
 ```@example abc
 img = testimage("walkbridge");
-@gp palette(:gray) recipe(img, "flipy rot=15deg")
+@gp palette(:gray1) recipe(img, "flipy rot=15deg")
 saveas("recipes007c") # hide
 ```
 ![](assets/recipes007c.png)

docs/src/style.md

@@ -1,6 +1,6 @@
 # Style Guide
 
-The **Gnuplot.jl** loose syntax allows to create a plot using very different approaches.  While this was one of the initial purposes for the package, it may lead to decreased code readability if not used judiciously.
+The **Gnuplot.jl** loose syntax allows to create a plot using very different approaches.  While this was one of the initial purposes for the package, it may lead to a reduced code readability if not used judiciously.
 
 Here I will summarize a few, non-mandatory, guidelines which allows to maintain a neat syntax and a high readability:
 

docs/src/terminals.md

@@ -4,11 +4,7 @@ Gnuplot provides dozens of terminals to display plots or export them into files
 
 To use a specific terminal for interactive use you may either set it as initialization command for all new session with (see [Options](@ref)):
 ```julia
-Gnuplot.options.term = "wxt")
-```
-or directly send the command to a specific session (see [Direct command execution](@ref))
-```julia
-gpexec("set term wxt")
+Gnuplot.options.term = "wxt"
 ```
 See official [gnuplot documentation](http://gnuplot.sourceforge.net/documentation.html) for further info on terminals and their options.
 
@@ -16,13 +12,13 @@ See official [gnuplot documentation](http://gnuplot.sourceforge.net/documentatio
 ## Interactive terminals (`wxt` and `qt`)
 The multiplatform `wxt` and `qt` terminals are among the most widely used ones for their nicely looking outputs on display and for their interactive capabilities.
 
-You may set them as terminal with:
+You may use such terminals with:
 ```
-"set term wxt size 800,600"
+Gnuplot.options.term = "wxt size 800,600"
 ```
 or
 ```
-"set term qt  size 800,600"
+Gnuplot.options.term = "qt  size 800,600"
 ```
 (the `size 800,600` is optional and can be omitted).
 
@@ -30,9 +26,35 @@ Press the `h` key on the window to display an help message with all available ke
 
 
 ## Plot in a terminal application (`dumb`, `sixel` and `sixelgd`)
-Gnuplot supports plotting in a terminal application, with no need for X11 or other GUI support, via the `dumb`, `sixel` and `sixelgd` terminals.  These are extremely useful when you run Julia on a remote shell through `ssh`, with no X11 forwarding.
+Gnuplot supports plotting in a terminal application, with no need for X11 or other GUI support, via the `dumb`, `sixel` and `sixelgd` terminals.  These are extremely useful when you run Julia on a remote shell through `ssh`, with no X11 forwarding. The `dumb` terminal uses ASCII characters to draw a plot, while `sixel` and `sixelgd` actually use bitmaps (but require Sixel support to be enabled in the terminal, e.g. `xterm -ti vt340`).
 
-The `dumb` terminal uses ASCII characters to draw a plot, while `sixel` and `sixelgd` actually use bitmaps (but require Sixel support to be enabled in the terminal, e.g. `xterm -ti vt340`).  A sixel plot on `xterm` looks as follows:
+Dumb terminal can be used as follows:
+
+```jldoctest; setup = :(using Gnuplot)
+julia> origterm = Gnuplot.options.term;
+
+julia> Gnuplot.options.term = "dumb size 60,15";
+
+julia> @gp "plot sin(x)"
+
+    1 +-------------------------------------------------+
+  0.8 |-+         *+ *         + ** **      +    *  * +-|
+  0.6 |-+        *   **          *   *   sin(x) *******-|
+  0.4 |*+        *    *         *     *         *    *+-|
+  0.2 |*+       *      *        *     *        *      *-|
+    0 |*+       *      *       *       *       *      *-|
+      | *      *       *       *       *      *        *|
+ -0.2 |-*      *        *     *        *      *       +*|
+ -0.4 |-+*    *         *     *         *    *        +*|
+ -0.6 |-+*    *          *   *          **   *        +-|
+ -0.8 |-+ *  *     +     ** ** +         *  *         +-|
+   -1 +-------------------------------------------------+
+     -10          -5           0            5           10
+
+julia> Gnuplot.options.term = origterm;
+
+```
+A sixel plot on `xterm` looks as follows:
 ![](assets/sixelgd.png)
 
 The above terminals are available if gnuplot has been compiled with the `--with-bitmap-terminals` option enabled and Libgd (only for `sixelgd`).
@@ -58,7 +80,7 @@ Gnuplot is also able to export vector (i.e. non-raster) plots through the `svg`
 The `cairolatex` terminal allows to produce high quality plots by splitting the output into a PDF file (containing a rasterized image of a plot) and a `.tex` file (containing all the text as ``\LaTeX`` code).  The following example shows how to write plot tics and an equation in ``\LaTeX``:
 ```julia
 x = LinRange(-2pi, 2pi, 1000)
-@gp t="Polynomial approximation of sin(x)"  "set style fill transparent solid 0.6 noborder"
+@gp tit="Polynomial approximation of sin(x)"  "set style fill transparent solid 0.6 noborder"
 @gp :- raw"""set xtics ('$-\pi$' -pi, '$-\pi/2$' -pi/2, 0, '$\pi/2$' pi/2, '$\pi$' pi)"""
 @gp :- xr=3.8.*[-1, 1] yr=[-1.5,1.5] key="box opaque left horiz" linetypes(:Blues_3) "set grid front"
 latex = raw"""\begin{minipage}[c]{\textwidth}\begin{equation*}""" *

src/Gnuplot.jl

@@ -7,7 +7,7 @@ import Base.reset
 import Base.write
 import Base.show
 
-export session_names, dataset_names, palette_names, linetypes, palette,
+export session_names, dataset_names, palette_names, linetypes, palette_levels, palette,
     terminal, terminals, test_terminal,
     stats, @gp, @gsp, save, gpexec,
     boxxy, contourlines, dgrid3d, hist, recipe, gpvars, gpmargins, gpranges
@@ -236,12 +236,18 @@ const sessions = OrderedDict{Symbol, Session}()
 const options = Options()
 
 function __init__()
-    # Check whether we are running in a IJulia or Juno session.
+    # Check whether we are running in an IJulia, Juno, VSCode or Pluto session.
     # (copied from Gaston.jl).
     options.gpviewer = !(
         ((isdefined(Main, :IJulia)  &&  Main.IJulia.inited)  ||
-         (isdefined(Main, :Juno)    &&  Main.Juno.isactive()))
+         (isdefined(Main, :Juno)    &&  Main.Juno.isactive()) ||
+         (isdefined(Main, :VSCodeServer)) ||
+         (isdefined(Main, :PlutoRunner)) )
     )
+    if isdefined(Main, :VSCodeServer)
+        # VS Code shows "dynamic" plots with fixed and small size :-(
+        options.mime[MIME"image/svg+xml"] = replace(options.mime[MIME"image/svg+xml"], "dynamic" => "")
+    end
 end
 
 
@@ -277,11 +283,11 @@ function parseKeywords(; kwargs...)
     ismissing(kw.zrange ) || (push!(out, replace("set zrange  [" * join(kw.zrange , ":") * "]", "NaN"=>"*")))
     ismissing(kw.cbrange) || (push!(out, replace("set cbrange [" * join(kw.cbrange, ":") * "]", "NaN"=>"*")))
     ismissing(kw.key    ) || (push!(out, "set key " * kw.key  * ""))
-    ismissing(kw.title  ) || (push!(out, "set title   \"" * kw.title  * "\""))
-    ismissing(kw.xlabel ) || (push!(out, "set xlabel  \"" * kw.xlabel * "\""))
-    ismissing(kw.ylabel ) || (push!(out, "set ylabel  \"" * kw.ylabel * "\""))
-    ismissing(kw.zlabel ) || (push!(out, "set zlabel  \"" * kw.zlabel * "\""))
-    ismissing(kw.cblabel) || (push!(out, "set cblabel \"" * kw.cblabel * "\""))
+    ismissing(kw.title  ) || (push!(out, "set title   '" * kw.title  * "'"))
+    ismissing(kw.xlabel ) || (push!(out, "set xlabel  '" * kw.xlabel * "'"))
+    ismissing(kw.ylabel ) || (push!(out, "set ylabel  '" * kw.ylabel * "'"))
+    ismissing(kw.zlabel ) || (push!(out, "set zlabel  '" * kw.zlabel * "'"))
+    ismissing(kw.cblabel) || (push!(out, "set cblabel '" * kw.cblabel * "'"))
     ismissing(kw.xlog   ) || (push!(out, (kw.xlog  ?  ""  :  "un") * "set logscale x"))
     ismissing(kw.ylog   ) || (push!(out, (kw.ylog  ?  ""  :  "un") * "set logscale y"))
     ismissing(kw.zlog   ) || (push!(out, (kw.zlog  ?  ""  :  "un") * "set logscale z"))
@@ -298,7 +304,6 @@ function parseKeywords(; kwargs...)
     ismissing(kw.rmargin) ||  push!(out, (kw.rmargin == ""  ?  "unset rmargin"  :  "set rmargin at screen $(kw.rmargin)"))
     ismissing(kw.bmargin) ||  push!(out, (kw.bmargin == ""  ?  "unset bmargin"  :  "set bmargin at screen $(kw.bmargin)"))
     ismissing(kw.tmargin) ||  push!(out, (kw.tmargin == ""  ?  "unset tmargin"  :  "set tmargin at screen $(kw.tmargin)"))
-
     return join(out, ";\n")
 end
 
@@ -514,7 +519,6 @@ function readTask(gp::GPSession)
     delete!(sessions, gp.sid)
 end
 
-
 function GPSession(sid::Symbol)
     session = DrySession(sid)
     if !options.dry
@@ -529,13 +533,16 @@ function GPSession(sid::Symbol)
     end
 
     pin  = Base.Pipe()
+    pout = Base.Pipe()
     perr = Base.Pipe()
-    proc = run(pipeline(`$(options.cmd)`, stdin=pin, stdout=stdout, stderr=perr), wait=false)
+    proc = run(pipeline(`$(options.cmd)`, stdin=pin, stdout=pout, stderr=perr), wait=false)
     chan = Channel{String}(32)
 
     # Close unused sides of the pipes
+    Base.close(pout.in)
     Base.close(perr.in)
     Base.close(pin.out)
+    Base.start_reading(pout.out)
     Base.start_reading(perr.out)
 
     out = GPSession(getfield.(Ref(session), fieldnames(DrySession))...,
@@ -544,11 +551,19 @@ function GPSession(sid::Symbol)
 
     # Start reading tasks
     @async readTask(out)
+    @async while !eof(pout) # see PR #51
+        write(stdout, readavailable(pout))
+    end
 
     # Read gnuplot default terminal
     if options.term == ""
         options.term = terminal()
     end
+
+    # The stderr of the gnuplot process goes to Julia which can parse
+    # UTF8 characters (regardless of the terminal).
+    gpexec("set encoding utf8")
+
     return out
 end
 
@@ -698,7 +713,7 @@ end
 function DatasetBin(cols::Vararg{AbstractVector, N}) where N
     source = "binary record=$(length(cols[1])) format='"
     types = Vector{DataType}()
-    (length(cols) == 1)  &&  (source *= "%int")
+    #(length(cols) == 1)  &&  (source *= "%int")
     for i in 1:length(cols)
         @assert length(cols[1]) == length(cols[i])
         if     isa(cols[i][1], Int32);   push!(types, Int32);   source *= "%int"
@@ -715,7 +730,7 @@ function DatasetBin(cols::Vararg{AbstractVector, N}) where N
     (path, io) = mktemp()
     source = " '$path' $source"
     for row in 1:length(cols[1])
-        (length(cols) == 1)  &&  (write(io, convert(Int32, row)))
+        #(length(cols) == 1)  &&  (write(io, convert(Int32, row)))
         for col in 1:length(cols)
             write(io, convert(types[col], cols[col][row]))
         end
@@ -803,7 +818,7 @@ function useBinaryMethod(args...)
     elseif options.preferred_format == :auto
         if (length(args) == 1)  &&  isa(args[1], AbstractMatrix)
             binary = true
-        elseif all(ndims.(args) .== 1)
+        elseif all(ndims.(args) .== 1)  &&  all(Base.:<:.(eltype.(args), Real))
             s = sum(length.(args))
             if s > 1e4
                 binary = true
@@ -911,9 +926,10 @@ function execall(gp::GPSession; term::AbstractString="", output::AbstractString=
     if term != ""
         former_term = writeread(gp, "print GPVAL_TERM")[1]
         former_opts = writeread(gp, "print GPVAL_TERMOPTIONS")[1]
+        gpexec(gp, "unset multiplot")
         gpexec(gp, "set term $term")
     end
-    (output != "")  &&  gpexec(gp, "set output '$output'")
+    (output != "")  &&  gpexec(gp, "set output '$(replace(output, "'" => "''"))'")
 
     # printstyled("Plotting with terminal: " * terminal() * "\n", color=:blue, bold=true)
 
@@ -1105,15 +1121,24 @@ function parseArguments(_args...)
             end
             insert!(args, pos, string(strip(arg[1])) => nothing)
         elseif isa(arg, AbstractArray) &&            # ==> a dataset column
-            ((valtype(arg) <: Real)    ||
-             (valtype(arg) <: AbstractString))  ;
+            ((nonmissingtype(eltype(arg)) <: Real)    ||
+             (nonmissingtype(eltype(arg)) <: AbstractString))  ;
         elseif isa(arg, Real)                        # ==> a dataset column with only one row
             args[pos] = [arg]
         elseif isa(arg, Dataset)                ;    # ==> a Dataset object
         elseif hasmethod(recipe, tuple(typeof(arg))) # ==> implicit recipe
             # @info which(recipe, tuple(typeof(arg)))  # debug
             deleteat!(args, pos)
-            insert!(args, pos, recipe(arg))
+            pe = recipe(arg)
+            if isa(pe, PlotElement)
+                insert!(args, pos, pe)
+            elseif isa(pe, Vector{PlotElement})
+                for i in 1:length(pe)
+                    insert!(args, pos, pe[i])
+                end
+            else
+                error("Recipe must return a PlotElement or Vector{PlotElement}")
+            end
             continue
         elseif isa(arg, Vector{PlotElement})         # ==> explicit recipe (vector)
             deleteat!(args, pos)
@@ -1128,40 +1153,54 @@ function parseArguments(_args...)
         pos += 1
     end
 
-    # Third pass: convert data into Dataset objetcs
+    # Third pass: convert data into Dataset objects
     pos = 1
+    accum = Vector{AbstractArray}()
     while pos <= length(args)
         arg = args[pos]
-        if isa(arg, AbstractArray)   &&      # ==> beginning of a dataset
-            ((valtype(arg) <: Real)  ||
-             (valtype(arg) <: AbstractString))
+        taken = false
 
-            # Collect all data
-            accum = Vector{AbstractArray}()
-            while isa(arg, AbstractArray)  &&
-                ((valtype(arg) <: Real)    ||
-                 (valtype(arg) <: AbstractString))
+        if isa(arg, AbstractArray)
+            if nonmissingtype(eltype(arg)) != eltype(arg)
+                @assert nonmissingtype(eltype(arg)) <: AbstractFloat "Missing values are supported only on arrays of floats"
+                arg = replace(arg, missing => NaN)
+            end
+            tt = eltype(arg)
+
+            # Try to convert into Int, Float64 and String
+            if (tt  <: Integer)  &&  !(tt <: Int)
+                arg = convert(Array{Int}, arg)
+            elseif (tt  <: AbstractFloat)  &&  !(tt <: Float64)
+                arg = convert(Array{Float64}, arg)
+            elseif (tt  <: AbstractString)  &&  !(tt <: String)
+                arg = convert(Array{String}, arg)
+            end
+
+            tt = eltype(arg)
+            if  (tt <: Real)  ||
+                (tt <: AbstractString)
                 push!(accum, arg)
                 deleteat!(args, pos)
-                if pos <= length(args)
-                    arg = args[pos]
-                else
-                    break
+                taken = true
             end
         end
 
+        if !taken  ||  (pos > length(args))
+            if length(accum) > 0
                 mm = extrema(length.(accum))
-            if mm[1] == 0
-                # empty Dataset
+                if mm[1] == 0   # empty Dataset
                     @assert mm[1] == mm[2] "At least one input array is empty, while other(s) are not"
                     d = DatasetEmpty()
                 else
                     d = Dataset(accum)
                 end
                 insert!(args, pos, d)
+                empty!(accum)
             end
+
             pos += 1
         end
+    end
 
     # Fourth pass: collect PlotElement objects
     mid = 0
@@ -1321,7 +1360,7 @@ end
 
 Return the **Gnuplot.jl** package version.
 """
-version() = v"1.3.0"
+version() = v"1.4.1"
 
 # ---------------------------------------------------------------------
 """
@@ -1672,6 +1711,34 @@ function linetypes(cmap::ColorScheme; lw=1, ps=1, dashed=false, rev=false)
 end
 
 
+"""
+    palette_levels(cmap::ColorScheme; rev=false, smooth=false)
+    palette_levels(s::Symbol; rev=false, smooth=false)
+
+Convert a `ColorScheme` object into a `Tuple{Vector{Float64}, Vector{String}, Int}` containing:
+- the numeric levels (between 0 and 1 included) corresponding to colors in the palette;
+- the corresponding colors (as hex strings);
+- the total number of different colors in the palette.
+
+If the argument is a `Symbol` it is interpreted as the name of one of the predefined schemes in [ColorSchemes](https://juliagraphics.github.io/ColorSchemes.jl/stable/basics/#Pre-defined-schemes-1).
+
+If `rev=true` the palette is reversed.  If `smooth=true` the palette is interpolated in 256 levels.
+"""
+palette_levels(s::Symbol; kwargs...) = palette_levels(colorschemes[s]; kwargs...)
+function palette_levels(cmap::ColorScheme; rev=false, smooth=false)
+    levels = OrderedDict{Float64, String}()
+    for x in LinRange(0, 1, (smooth  ?  256  : length(cmap.colors)))
+        if rev
+            color = get(cmap, 1-x)
+        else
+            color = get(cmap, x)
+        end
+        levels[x] = "#" * Colors.hex(color)
+    end
+    return (collect(keys(levels)), collect(values(levels)), length(cmap.colors))
+end
+
+
 """
     palette(cmap::ColorScheme; rev=false, smooth=false)
     palette(s::Symbol; rev=false, smooth=false)
@@ -1682,19 +1749,13 @@ If the argument is a `Symbol` it is interpreted as the name of one of the predef
 
 If `rev=true` the palette is reversed.  If `smooth=true` the palette is interpolated in 256 levels.
 """
+function palette(values::Vector{Float64}, levels::Vector{String}, ncolors::Int)
+    str = string.(values) .* " '" .* levels .* "'"
+    return "set palette defined (" * join(str, ", ") * ")\nset palette maxcol $(ncolors)\n"
+end
 palette(s::Symbol; kwargs...) = palette(colorschemes[s]; kwargs...)
-function palette(cmap::ColorScheme; rev=false, smooth=false)
-    levels = Vector{String}()
-    for x in LinRange(0, 1, (smooth  ?  256  : length(cmap.colors)))
-        if rev
-            color = get(cmap, 1-x)
-        else
-            color = get(cmap, x)
-        end
-        push!(levels, "$x '#" * Colors.hex(color) * "'")
-    end
-    return "set palette defined (" * join(levels, ", ") * ")\nset palette maxcol $(length(cmap.colors))\n"
-end
+palette(cmap::ColorScheme; kwargs...) =
+    palette(palette_levels(cmap; kwargs...)...)
 
 
 # --------------------------------------------------------------------
@@ -1820,16 +1881,20 @@ function hist(v::Vector{T}; range=[NaN,NaN], bs=NaN, nbins=0, pad=true) where T
         if sum(hh.weights) < length(i)
             j = findall(v[i] .== range[2])
             @assert length(j) == (length(i) - sum(hh.weights))
+            if length(hh.weights) > 0
                 hh.weights[end] += length(j)
+            else
+                push!(hh.weights, length(j))
+            end
         end
     else
         hh = fit(Histogram, v[i], closed=:left)
     end
     @assert sum(hh.weights) == length(i)
     x = collect(hh.edges[1])
-    x = (x[1:end-1] .+ x[2:end]) ./ 2
+    binsize = isfinite(bs) ? bs : x[2] - x[1]
+    length(x) > 1 && (x = (x[1:end-1] .+ x[2:end]) ./ 2)
     h = hh.weights
-    binsize = x[2] - x[1]
     if pad
         x = [x[1]-binsize, x..., x[end]+binsize]
         h = [0, h..., 0]
@@ -1893,6 +1958,35 @@ function hist(v1::Vector{T1}, v2::Vector{T2};
     return Histogram2D(x1, x2, hh.weights, binsize1, binsize2)
 end
 
+# Allow missing values in input
+function hist(v::Vector{Union{Missing,T}}; kw...) where T <: Real
+    ii = findall(.!ismissing.(v))
+    @info "Neglecting missing values ($(length(v) - length(ii)))"
+    hist(convert(Vector{T}, v[ii]); kw...)
+end
+
+function hist(v1::Vector{Union{Missing,T1}}, v2::Vector{T2}; kw...) where {T1 <: Real, T2 <: Real}
+    ii = findall(.!ismissing.(v1)  .&
+                 .!ismissing.(v2)  )
+    @info "Neglecting missing values ($(length(v1) - length(ii)))"
+    hist(convert(Vector{T1}, v1[ii]), convert(Vector{T2}, v2[ii]), kw...)
+end
+
+function hist(v1::Vector{T1}, v2::Vector{Union{Missing, T2}}; kw...) where {T1 <: Real, T2 <: Real}
+    ii = findall(.!ismissing.(v1)  .&
+                 .!ismissing.(v2)  )
+    @info "Neglecting missing values ($(length(v1) - length(ii)))"
+    hist(convert(Vector{T1}, v1[ii]), convert(Vector{T2}, v2[ii]), kw...)
+end
+
+function hist(v1::Vector{Union{Missing,T1}}, v2::Vector{Union{Missing,T2}}; kw...) where {T1 <: Real, T2 <: Real}
+    ii = findall(.!ismissing.(v1)  .&
+                 .!ismissing.(v2)  )
+    @info "Neglecting missing values ($(length(v1) - length(ii)))"
+    hist(convert(Vector{T1}, v1[ii]), convert(Vector{T2}, v2[ii]), kw...)
+end
+
+
 
 # --------------------------------------------------------------------
 """
@@ -2254,7 +2348,7 @@ function gpvars(sid::Symbol)
         if length(s) == 2
             key = Symbol(s[1])
             if s[2][1] == '"'
-                out[key] = s[2][2:end-1]
+                out[key] = s[2][2:prevind(s[2], end, 1)]
             else
                 try
                     out[key] = Meta.parse(s[2])

test/runtests.jl

@@ -286,4 +286,8 @@ Gnuplot.quit(:default)
 Gnuplot.options.dry = true
 @gp hist(randn(1000))
 
+# Various hist() corner cases
+@gp hist([1,2,3], bs=2)
+@gp hist([1,1,1], bs=1)
+
 Gnuplot.quitall()