Julia PyPlot control parameters in multiple plot

New to Julia
1

Hello,
I am creating some plot in Julia using PyPlot. How can I how can I combine plots with PyPlot?
For instance, I would like one line in solid red the other in dotted green:

julia> x = range(0; stop=2*pi, length=1000)
0.0:0.006289474781961547:6.283185307179586

julia> y1 = sin.(3 * x + 4 * cos.(2 * x))
1000-element Array{Float64,1}:
 -0.7568024953079282
 -0.7687979429150046
 -0.7801330261327849
 -0.790830536475742
 -0.800913192079596
 -0.8104035427077365
  ⋮
 -0.6861303352619349
 -0.7017645466519309
 -0.7166271329853839
 -0.7307395907784272
 -0.7441239200875579
 -0.7568024953079278

julia> y2 = sin.(2 * x + 5 * cos.(3 * x))
1000-element Array{Float64,1}:
 -0.9589242746631385
 -0.9555431333512879
 -0.9525745225417045
 -0.9500689261982551
 -0.9480672919504057
 -0.9466011427015437
  ⋮
 -0.9795705265038878
 -0.975224815064202
 -0.9708927507542918
 -0.9666738797537784
 -0.9626578163088578
 -0.9589242746631386
julia> myPlot = plot(x, y1, x, y2, linewidth=2.0, color="green", "red", linestyle = "-", ".")
3-element Array{PyCall.PyObject,1}:
 PyObject <matplotlib.lines.Line2D object at 0x7f9b5feadbe0>
 PyObject <matplotlib.lines.Line2D object at 0x7f9b5fe7af98>
 PyObject <matplotlib.lines.Line2D object at 0x7f9b5fdc5240>
julia> xlabel("X-values")
PyObject Text(0.5, 23.52222222222222, 'X-values')
julia> ylabel("sin(x)")
PyObject Text(44.222222222222214, 0.5, 'sin(x)')
julia> title("simulation")
PyObject Text(0.5, 1.0, 'simulation')
julia> savefig("./plot.png", dpi = 100, format = "png", transparent = false)

But the graph is not really as I wanted:
plot
This compared to:

julia> myPlot = plot(x, y1, x, y2, linewidth=2.0)
2-element Array{PyCall.PyObject,1}:
 PyObject <matplotlib.lines.Line2D object at 0x7f9b5ffffb70>
 PyObject <matplotlib.lines.Line2D object at 0x7f9b5fde9d68>
julia> xlabel("X-values")
PyObject Text(0.5, 23.52222222222222, 'X-values')
julia> ylabel("sin(x)")
PyObject Text(60.347222222222214, 0.5, 'sin(x)')
julia> title("simulation")
PyObject Text(0.5, 1.0, 'simulation')
julia> savefig("./plot2.png", dpi = 100, format = "png", transparent = false)

plot2
I also tried to provide arrays but it was not good:

julia> myPlot = plot(x, y1, x, y2, linewidth=2.0, color=["green", "red"], linestyle = ["-", "."])
ERROR: PyError ($(Expr(:escape, :(ccall(#= /home/gigiux/.julia/packages/PyCall/ttONZ/src/pyfncall.jl:44 =# @pysym(:PyObject_Call), PyPtr, (PyPtr, PyPtr, PyPtr), o, pyargsptr, kw))))) <class 'ValueError'>
ValueError("Unrecognized linestyle: ['-', '.']",)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/pyplot.py", line 2813, in plot
    is not None else {}), **kwargs)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/__init__.py", line 1810, in inner
    return func(ax, *args, **kwargs)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/axes/_axes.py", line 1611, in plot
    for line in self._get_lines(*args, **kwargs):
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/axes/_base.py", line 393, in _grab_next_args
    yield from self._plot_args(this, kwargs)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/axes/_base.py", line 383, in _plot_args
    seg = func(x[:, j % ncx], y[:, j % ncy], kw, kwargs)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/axes/_base.py", line 288, in _makeline
    seg = mlines.Line2D(x, y, **kw)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/lines.py", line 381, in __init__
    self.set_linestyle(linestyle)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/lines.py", line 1101, in set_linestyle
    self._us_dashOffset, self._us_dashSeq = _get_dash_pattern(ls)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/lines.py", line 47, in _get_dash_pattern
    raise ValueError('Unrecognized linestyle: %s' % str(style))

Stacktrace:
 [1] pyerr_check at /home/gigiux/.julia/packages/PyCall/ttONZ/src/exception.jl:60 [inlined]
 [2] pyerr_check at /home/gigiux/.julia/packages/PyCall/ttONZ/src/exception.jl:64 [inlined]
 [3] macro expansion at /home/gigiux/.julia/packages/PyCall/ttONZ/src/exception.jl:84 [inlined]
 [4] __pycall!(::PyCall.PyObject, ::Ptr{PyCall.PyObject_struct}, ::PyCall.PyObject, ::PyCall.PyObject) at /home/gigiux/.julia/packages/PyCall/ttONZ/src/pyfncall.jl:44
 [5] _pycall!(::PyCall.PyObject, ::PyCall.PyObject, ::Tuple{StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}},Array{Float64,1},StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}},Array{Float64,1}}, ::Int64, ::PyCall.PyObject) at /home/gigiux/.julia/packages/PyCall/ttONZ/src/pyfncall.jl:29
 [6] _pycall!(::PyCall.PyObject, ::PyCall.PyObject, ::Tuple{StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}},Array{Float64,1},StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}},Array{Float64,1}}, ::Base.Iterators.Pairs{Symbol,Any,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:linewidth, :color, :linestyle),Tuple{Float64,Array{String,1},Array{String,1}}}}) at /home/gigiux/.julia/packages/PyCall/ttONZ/src/pyfncall.jl:11
 [7] #pycall#110(::Base.Iterators.Pairs{Symbol,Any,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:linewidth, :color, :linestyle),Tuple{Float64,Array{String,1},Array{String,1}}}}, ::Function, ::PyCall.PyObject, ::Type{PyCall.PyAny}, ::StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}, ::Vararg{Any,N} where N) at /home/gigiux/.julia/packages/PyCall/ttONZ/src/pyfncall.jl:86
 [8] (::getfield(PyCall, Symbol("#kw##pycall")))(::NamedTuple{(:linewidth, :color, :linestyle),Tuple{Float64,Array{String,1},Array{String,1}}}, ::typeof(PyCall.pycall), ::PyCall.PyObject, ::Type{PyCall.PyAny}, ::StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}, ::Vararg{Any,N} where N) at ./none:0
 [9] #plot#85(::Base.Iterators.Pairs{Symbol,Any,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:linewidth, :color, :linestyle),Tuple{Float64,Array{String,1},Array{String,1}}}}, ::Function, ::StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}, ::Vararg{Any,N} where N) at /home/gigiux/.julia/packages/PyPlot/cdCMF/src/PyPlot.jl:177
 [10] (::getfield(PyPlot, Symbol("#kw##plot")))(::NamedTuple{(:linewidth, :color, :linestyle),Tuple{Float64,Array{String,1},Array{String,1}}}, ::typeof(plot), ::StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}, ::Vararg{Any,N} where N) at ./none:0
 [11] top-level scope at none:0

How to a fine control the parameters in PyPlot?

2

Have a look at the examples at either
Plot Examples
or
the Julia Plots Gallery.

1 Like
3

The easiest thing is just to call plot multiple times. The lines will be added to the same plot, but then you can control their properties individually.

plot(x, y1, linewidth=2.0, color="green", linestyle = "-")
plot(x, y2, linewidth=2.0, color="red", linestyle = ":")
4

But I got:

julia> myPlot = plot(x, y1, linewidth=2.0, color="green", linestyle = "-")
1-element Array{PyCall.PyObject,1}:
 PyObject <matplotlib.lines.Line2D object at 0x7f910db93cf8>

julia> myPlot = plot(x, y2, linewidth=2.0, color="red", linestyle = ".")
ERROR: PyError ($(Expr(:escape, :(ccall(#= /home/gigiux/.julia/packages/PyCall/ttONZ/src/pyfncall.jl:44 =# @pysym(:PyObject_Call), PyPtr, (PyPtr, PyPtr, PyPtr), o, pyargsptr, kw))))) <class 'ValueError'>
ValueError("Invalid linestyle '.'; see docs of Line2D.set_linestyle for valid values",)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/pyplot.py", line 2813, in plot
    is not None else {}), **kwargs)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/__init__.py", line 1810, in inner
    return func(ax, *args, **kwargs)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/axes/_axes.py", line 1611, in plot
    for line in self._get_lines(*args, **kwargs):
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/axes/_base.py", line 393, in _grab_next_args
    yield from self._plot_args(this, kwargs)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/axes/_base.py", line 383, in _plot_args
    seg = func(x[:, j % ncx], y[:, j % ncy], kw, kwargs)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/axes/_base.py", line 288, in _makeline
    seg = mlines.Line2D(x, y, **kw)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/lines.py", line 381, in __init__
    self.set_linestyle(linestyle)
  File "/home/gigiux/.local/lib/python3.6/site-packages/matplotlib/lines.py", line 1095, in set_linestyle
    .format(ls))

Stacktrace:
 [1] pyerr_check at /home/gigiux/.julia/packages/PyCall/ttONZ/src/exception.jl:60 [inlined]
 [2] pyerr_check at /home/gigiux/.julia/packages/PyCall/ttONZ/src/exception.jl:64 [inlined]
 [3] macro expansion at /home/gigiux/.julia/packages/PyCall/ttONZ/src/exception.jl:84 [inlined]
 [4] __pycall!(::PyCall.PyObject, ::Ptr{PyCall.PyObject_struct}, ::PyCall.PyObject, ::PyCall.PyObject) at /home/gigiux/.julia/packages/PyCall/ttONZ/src/pyfncall.jl:44
 [5] _pycall!(::PyCall.PyObject, ::PyCall.PyObject, ::Tuple{StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}},Array{Float64,1}}, ::Int64, ::PyCall.PyObject) at /home/gigiux/.julia/packages/PyCall/ttONZ/src/pyfncall.jl:29
 [6] _pycall!(::PyCall.PyObject, ::PyCall.PyObject, ::Tuple{StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}},Array{Float64,1}}, ::Base.Iterators.Pairs{Symbol,Any,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:linewidth, :color, :linestyle),Tuple{Float64,String,String}}}) at /home/gigiux/.julia/packages/PyCall/ttONZ/src/pyfncall.jl:11
 [7] #pycall#110(::Base.Iterators.Pairs{Symbol,Any,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:linewidth, :color, :linestyle),Tuple{Float64,String,String}}}, ::Function, ::PyCall.PyObject, ::Type{PyCall.PyAny}, ::StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}, ::Vararg{Any,N} where N) at /home/gigiux/.julia/packages/PyCall/ttONZ/src/pyfncall.jl:86
 [8] (::getfield(PyCall, Symbol("#kw##pycall")))(::NamedTuple{(:linewidth, :color, :linestyle),Tuple{Float64,String,String}}, ::typeof(PyCall.pycall), ::PyCall.PyObject, ::Type{PyCall.PyAny}, ::StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}, ::Vararg{Any,N} where N) at ./none:0
 [9] #plot#85(::Base.Iterators.Pairs{Symbol,Any,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:linewidth, :color, :linestyle),Tuple{Float64,String,String}}}, ::Function, ::StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}, ::Vararg{Any,N} where N) at /home/gigiux/.julia/packages/PyPlot/cdCMF/src/PyPlot.jl:177
 [10] (::getfield(PyPlot, Symbol("#kw##plot")))(::NamedTuple{(:linewidth, :color, :linestyle),Tuple{Float64,String,String}}, ::typeof(plot), ::StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}, ::Vararg{Any,N} where N) at ./none:0
 [11] top-level scope at none:0

julia> myPlot = plot!(x, y2, linewidth=2.0, color="red", linestyle = ".")
ERROR: UndefVarError: plot! not defined
Stacktrace:
 [1] top-level scope at none:0

julia>
5

Did you read the error message? It says exactly what your problem is: '.' is an invalid linestyle. If you want a dotted line, you can use linestyle=":". As the message says, the valid linestyles are listed in the Line2D.set_linestyle documentation, which you can easily google.

2 Likes
6

You were right, sorry. I got the linestyle = “.” probably from another plot function’s help. It worked.
plot