From 93f9e9ac023fab53f90186a09781a53732cc8ac0 Mon Sep 17 00:00:00 2001
From: Matti Pastell <matti.pastell@helsinki.fi>
Date: Wed, 2 Nov 2016 09:26:10 +0200
Subject: [PATCH] Fix plotly output for markdown, fix examples

---
 examples/FIR_design.jl       |  6 ++-
 examples/FIR_design_plots.jl | 83 ++++++++++++++++++++++++++++++++++++
 src/plots.jl                 |  5 +++
 3 files changed, 92 insertions(+), 2 deletions(-)
 create mode 100644 examples/FIR_design_plots.jl

diff --git a/examples/FIR_design.jl b/examples/FIR_design.jl
index 2a49c0d..39fc0a2 100644
--- a/examples/FIR_design.jl
+++ b/examples/FIR_design.jl
@@ -56,7 +56,6 @@ end
 #' We will use the Hamming window, which is defined as:
 #' $w(n) = \alpha - \beta\cos\frac{2\pi n}{N-1}$, where $\alpha=0.54$ and $\beta=0.46$
 
-
 fs = 20
 f = digitalfilter(Lowpass(5, fs = fs), FIRWindow(hamming(61)))
 w = linspace(0, pi, 1024)
@@ -67,8 +66,11 @@ h = FIRfreqz(f, w)
 #' The next code chunk is executed in term mode, see the [script](FIR_design.jl) for syntax.
 #+ term=true
 
-h_db = log10(abs(h))
+h_db = log10(abs(h));
 ws = w/pi*(fs/2)
+
+#+
+
 plot(y = h_db, x = ws, Geom.line,
       Guide.xlabel("Frequency (Hz)"), Guide.ylabel("Magnitude (db)"))
 
diff --git a/examples/FIR_design_plots.jl b/examples/FIR_design_plots.jl
new file mode 100644
index 0000000..6d7a976
--- /dev/null
+++ b/examples/FIR_design_plots.jl
@@ -0,0 +1,83 @@
+#' % FIR filter design with Julia
+#' % Matti Pastell
+#' % 21th April 2016
+
+#' # Introduction
+
+#' This an example of a julia script that can be published using
+#' [Weave](http://mpastell.github.io/Weave.jl/latest/usage/).
+#' The script can be executed normally using Julia
+#' or published to HTML or pdf with Weave.
+#' Text is written in markdown in lines starting with "`#'` " and code
+#' is executed and results are included in the published document.
+
+#' Notice that you don't need to define chunk options, but you can using
+#' `#+`. just before code e.g. `#+ term=True, caption='Fancy plots.'`.
+#' If you're viewing the published version have a look at the
+#' [source](FIR_design_plots.jl) to see the markup.
+
+
+#' # FIR Filter Design
+
+#' We'll implement lowpass, highpass and ' bandpass FIR filters. If
+#' you want to read more about DSP I highly recommend [The Scientist
+#' and Engineer's Guide to Digital Signal
+#' Processing](http://www.dspguide.com/) which is freely available
+#' online.
+
+#' ## Calculating frequency response
+
+#' DSP.jl package doesn't (yet) have a method to calculate the
+#' the frequency response of a FIR filter so we define it:
+
+using Plots, DSP
+plotly()
+
+function FIRfreqz(b::Array, w = linspace(0, π, 1024))
+    n = length(w)
+    h = Array{Complex64}(n)
+    sw = 0
+    for i = 1:n
+      for j = 1:length(b)
+        sw += b[j]*exp(-im*w[i])^-j
+      end
+      h[i] = sw
+      sw = 0
+    end
+    return h
+end
+
+
+#' ## Design Lowpass FIR filter
+
+#' Designing a lowpass FIR filter is very simple to do with DSP.jl, all you
+#' need to do is to define the window length, cut off frequency and the
+#' window. We will define a lowpass filter with cut off frequency at 5Hz for a signal
+#' sampled at 20 Hz.
+#' We will use the Hamming window, which is defined as:
+#' $w(n) = \alpha - \beta\cos\frac{2\pi n}{N-1}$, where $\alpha=0.54$ and $\beta=0.46$
+
+
+fs = 20
+f = digitalfilter(Lowpass(5, fs = fs), FIRWindow(hamming(61)))
+w = linspace(0, pi, 1024)
+h = FIRfreqz(f, w)
+
+#' ## Plot the frequency and impulse response
+
+#' The next code chunk is executed in term mode, see the [script](FIR_design.jl) for syntax.
+#+ term=true
+
+h_db = log10(abs(h));
+ws = w/pi*(fs/2)
+
+#+
+
+plot(ws, h_db,
+      xlabel = "Frequency (Hz)", ylabel = "Magnitude (db)")
+
+#' And again with default options
+
+h_phase = unwrap(-atan2(imag(h),real(h)))
+plot(ws, h_phase,
+    xlabel = "Frequency (Hz)", ylabel = "Phase (radians)")
diff --git a/src/plots.jl b/src/plots.jl
index 76032da..ee9af07 100644
--- a/src/plots.jl
+++ b/src/plots.jl
@@ -29,6 +29,11 @@ function Base.display(report::Report, m::MIME"image/svg+xml", data::Plots.Plot{P
     report.rich_output *= "\n" * div * "\n" * plot
 end
 
+function Base.display(report::Report, m::MIME"image/png", data::Plots.Plot{Plots.PlotlyBackend})#
+  display(report, MIME("image/svg+xml"), data)
+end
+
+
 #PNG or SVG is not working, output html
 function Base.display(report::Report, m::MIME"image/svg+xml", plot::Plots.Plot{Plots.PlotlyJSBackend})
   script = "<script src=\"https://cdn.plot.ly/plotly-latest.min.js\"></script>"