Category Archives: Shiny

Sunflowers for COLOURlovers

Andar, lo que es andar, anduve encima siempre de las nubes (Del tiempo perdido, Robe)

If you give importance to colours, maybe you know already COLOURlovers. As can be read in their website, COLOURlovers is a creative community where people from around the world create and share colors, palettes and patterns, discuss the latest trends and explore colorful articles… All in the spirit of love.

There is a R package called colourlovers which provides access to the COLOURlovers API. It makes very easy to choose nice colours for your graphics. I used clpalettes function to search for the top palettes of the website. Their names are pretty suggestive as well: Giant Goldfish, Thought Provoking, Adrift in Dreams, let them eat cake … Inspired by this post I have done a Shiny app to create colored flowers using that palettes. Seeds are arranged according to the golden angle. One example:

Some others:

You can play with the app here.

If you want to do your own sunflowers, here you have the code. This is the ui.R file:

library(colourlovers)
library(rlist)
top=clpalettes('top')
sapply(1:length(top), function(x) list.extract(top, x)$title)->titles

fluidPage(
  titlePanel("Sunflowers for COLOURlovers"),
  fluidRow(
    column(3,
           wellPanel(
             selectInput("pal", label = "Palette:", choices = titles),
             sliderInput("nob", label = "Number of points:", min = 200, max = 500, value = 400, step = 50)
           )
    ),
    mainPanel(
      plotOutput("Flower")
    )
  )
  )

And this is the server.R one:

library(shiny)
library(ggplot2)
library(colourlovers)
library(rlist)
library(dplyr)

top=clpalettes('top')
sapply(1:length(top), function(x) list.extract(top, x)$title)->titles

CreatePlot = function (ang=pi*(3-sqrt(5)), nob=150, siz=15, sha=21, pal="LoversInJapan") {
  
  list.extract(top, which(titles==pal))$colors %>% 
    unlist %>% 
    as.vector() %>% 
    paste0("#", .) -> all_colors
  
  colors=data.frame(hex=all_colors, darkness=colSums(col2rgb(all_colors)))
  colors %>% arrange(-darkness)->colors
  
  background=colors[1,"hex"] %>% as.character

  colors %>% filter(hex!=background) %>% .[,1] %>% as.vector()->colors

  ggplot(data.frame(r=sqrt(1:nob), t=(1:nob)*ang*pi/180), aes(x=r*cos(t), y=r*sin(t)))+
    geom_point(colour=sample(colors, nob, replace=TRUE, prob=exp(1:length(colors))), aes(size=(nob-r)), shape=16)+
    scale_x_continuous(expand=c(0,0), limits=c(-sqrt(nob)*1.4, sqrt(nob)*1.4))+
    scale_y_continuous(expand=c(0,0), limits=c(-sqrt(nob)*1.4, sqrt(nob)*1.4))+
    theme(legend.position="none",
          panel.background = element_rect(fill=background),
          panel.grid=element_blank(),
          axis.ticks=element_blank(),
          axis.title=element_blank(),
          axis.text=element_blank())}

function(input, output) {
 output$Flower=renderPlot({
    CreatePlot(ang=180*(3-sqrt(5)), nob=input$nob, siz=input$siz, sha=as.numeric(input$sha), pal=input$pal)
  }, height = 550, width = 550 )}

The Ex Libris Generator

Go ahead stomp your feet on the floorboards
Clap your hands if that’s really what you came here for
(Heaven, The Milk Carton Kids)

Inspired by curves created by the harmonograph, I have done a Shiny app to generate random images that you can personalize and use as an Exlibris.  You can try the App here. For me, an exlibris (also known as bookplates) can be a nice, original and useful present for book-lovers. This is an example:
exlibris8
More examples:

I always put the code at the end of my posts. Since I always have doubts about how many people are interested in what I do, today will be different. I will share the code with those who ask it to me in any of the following ways:

  • Sending me a direct message on Twitter
  • Droping me an email

Cheers!

Three Shiny Apps to Celebrate the Beauty of Maths

Mathematics knows no races or geographic boundaries; for mathematics, the cultural world is one country (David Hilbert)

One of the best decisions I took this year related with this blog was to move it to my own self-hosted domain using WordPress.org. It allows to me, for example, to embed dynamic JavaScript visualizations like this one. Another thing I can do now is to upload my Shiny Apps to share them with my readers. In this post I have gathered three Apps I made some time ago; you can play with them as well as get the code I wrote for each one:

  • The Harmonograph: This App simulates harmonograph drawings. An harmonograph is a mechanism which draws trajectories by means of two pendulums: one moves a pencil and the other one moves a platform with a piece of paper on it. Click here to try it.
  • Shiny Wool Skeins: This App, inspired by this post, creates a plot consisting of chords inside a circle . You can change colors as well as the number and quality of the chords. Click here to try it.
  • The Coaster Maker: With this App you can create your own coasters using hypocicloids. Click here to try it.

I want to thank to my friend Jorge, without whom I would not have been able to make Shiny work in my server.

The Coaster Maker by Shiny

The word you invented is well formed and could be used in the Italian language (The Accademia della Crusca regarding to the word “Petaloso”, recently invented by an eight-year-old boy)

Are you tired of your old coasters? Do you like to make things by your own? Do you have a PC and a printer at home? If you answered yes to all these questions, just follow these simple instructions:

  • Install R and RStudio in your PC
  • Open RStudio and create a new Shiny Web App multiple file (ui.R/server.R)
  • Substitute sample code of each file by the code below
  • Press Run App
  • Press buttom Get your coaster! until you obtain a image you like
  • Print the image
  • Cut out the image
  • Place on the coaster your favorite drinking

These are some examples:

This is the code of ui.R

#
# This is the user-interface definition of a Shiny web application. You can
# run the application by clicking 'Run App' above.
#
# Find out more about building applications with Shiny here:
#
#    http://shiny.rstudio.com/
#
library(shiny)
shinyUI(fluidPage(
  titlePanel("The coaster maker"),
  sidebarLayout(
    sidebarPanel(
      #helpText(),
 
      # adding the new div tag to the sidebar
      tags$div(class="header", checked=NA,
               tags$p("This coasters are generated by hypocycloid curves.The curve is formed by the locus of a point,
                      attached to a circle, that rolls on the inside of another circle.
                      In the curve's equation the first part denotes the relative position between the two circles,
                      the second part denotes the rotation of the rolling circle.")),
      tags$div(class="header", checked=NA,
               HTML(
"More info <a href=\"http://www.2dcurves.com/roulette/rouletteh.html#rhodon\">here</a>")),
      actionButton('rerun','Get your coaster!')
    ),
    mainPanel(
      plotOutput("HarmPlot")
    )
  )
))

This is the code of server.R

# This is the server logic of a Shiny web application. You can run the
# application by clicking 'Run App' above.
#
# Find out more about building applications with Shiny here:
#
#    http://shiny.rstudio.com/
#
library(shiny)
library(ggplot2)
CreateDS = function ()
{
  t=seq(-31*pi, 31*pi, 0.002)
  a=sample(seq(from=1/31, to=29/31, by=2/31), 1)
  b=runif(1, min = 1, max = 3)
  data.frame(x=(1-a)*cos(a*t)+a*b*cos((1-a)*t), y=(1-a)*sin(a*t)-a*b*sin((1-a)*t))
}
shinyServer(function(input, output) {
  dat<-reactive({if (input$rerun) dat=CreateDS() else dat=CreateDS()})
    output$HarmPlot<-renderPlot({
    ggplot(dat())+
      geom_point(data=data.frame(x=0,y=0), aes(x,y), color=rgb(rbeta(1, .5, .5), rbeta(1, .5, .5), rbeta(1, .5, .5)) , shape=19, fill="yellow", size=220)+
      geom_polygon(aes(x, y), fill=rgb(rbeta(1, 2, 2), rbeta(1, 2, 2), rbeta(1, 2, 2))) +
      theme(legend.position="none",
            panel.background = element_rect(fill="white"),
            panel.grid=element_blank(),
            axis.ticks=element_blank(),
            axis.title=element_blank(),
            axis.text=element_blank())
  }, height = 500, width = 500)
})

Phyllotaxis By Shiny

Antonio, you don’t know what empathy is! (Cecilia, my beautiful wife)

Spirals are nice. In the wake of my previous post I have done a Shiny app to explore patterns generated by changing angle, shape and number of points of Fermat’s spiral equation. You can obtain an almost infinite number of images. This is just an example:
phyllotaxis12

I like thinking in imaginary flowers. This is why I called this experiment Phyllotaxis.
More examples:


Just one comment about code: I did the Shiny in just one R file as this guy suggested me some time ago because of this post.

This is the code. Do your own imaginary flowers:

library(shiny)
library(ggplot2)
CreatePlot = function (ang=pi*(3-sqrt(5)), nob=150, siz=15, alp=0.8, sha=16, col="black", bac="white") {
ggplot(data.frame(r=sqrt(1:nob), t=(1:nob)*ang*pi/180), aes(x=r*cos(t), y=r*sin(t)))+
geom_point(colour=col, alpha=alp, size=siz, shape=sha)+
scale_x_continuous(expand=c(0,0), limits=c(-sqrt(nob)*1.4, sqrt(nob)*1.4))+
scale_y_continuous(expand=c(0,0), limits=c(-sqrt(nob)*1.4, sqrt(nob)*1.4))+
theme(legend.position="none",
panel.background = element_rect(fill=bac),
panel.grid=element_blank(),
axis.ticks=element_blank(),
axis.title=element_blank(),
axis.text=element_blank())}
shinyApp(
ui = fluidPage(
titlePanel("Phyllotaxis by Shiny"),
fluidRow(
column(3,
wellPanel(
selectInput("col", label = "Colour of points:", choices = colors(), selected = "black"),
selectInput("bac", label = "Background colour:", choices = colors(), selected = "white"),
selectInput("sha", label = "Shape of points:",
choices = list("Empty squares" = 0, "Empty circles" = 1, "Empty triangles"=2,
"Crosses" = 3, "Blades"=4, "Empty diamonds"=5,
"Inverted empty triangles"=6, "Bladed squares"=7,
"Asterisks"=8, "Crosed diamonds"=9, "Crossed circles"=10,
"Stars"=11, "Cubes"=12, "Bladed circles"=13,
"Filled squares" = 15, "Filled circles" = 16, "Filled triangles"=17,
"Filled diamonds"=18), selected = 16),
sliderInput("ang", label = "Angle (degrees):", min = 0, max = 360, value = 180*(3-sqrt(5)), step = .05),
sliderInput("nob", label = "Number of points:", min = 1, max = 1500, value = 60, step = 1),
sliderInput("siz", label = "Size of points:", min = 1, max = 60, value = 10, step = 1),
sliderInput("alp", label = "Transparency:", min = 0, max = 1, value = .5, step = .01)
)
),
mainPanel(
plotOutput("Phyllotaxis")
)
)
),
server = function(input, output) {
output$Phyllotaxis=renderPlot({
CreatePlot(ang=input$ang, nob=input$nob, siz=input$siz, alp=input$alp, sha=as.numeric(input$sha), col=input$col, bac=input$bac)
}, height = 650, width = 650 )}
)

The 2D-Harmonograph In Shiny

If you wish to make an apple pie from scratch, you must first invent the universe (Carl Sagan)

I like Shiny and I can’t stop converting into apps some of my previous experiments: today is the turn of the harmonograph. This is a simple application since you only can press a button to generate a random harmonograph-simulated curve. I love how easy is to create a nice interactive app to play with from an existing code. The only trick in this case in to add a rerun button in the UI side and transfer the interaction to the server side using a simple if. Very easy. This is a screenshot of the application:

Shiny_2DHarmonograph

Press the button and you will get a new drawing. Most of them are nice scrawls and from time to time you will obtain beautiful shapely curves.

And no more candy words: It is time to complain. I say to RStudio with all due respect, you are very cruel. You let me to deploy my previous app to your server but you suspended it almost immediately for fifteen days due to “exceeded usage hours”. My only option is paying at least $440 per year to upgrade my current plan. I tried the ambrosia for an extremely short time. RStudio: Why don’t you launch a cheaper account? Why don’t you launch a free account with just one perpetual alive app at a time? Why don’t you increase the usage hours threshold? I can help you to calculate the return on investment of these scenarios.

Or, Why don’t you make me a gift for my next birthday? I promise to upload a new app per month to promote your stunning tool. Think about it and please let me know your conclusions.

Meanwhile I will run the app privately. This is the code to do it:

UI.R

# This is the user-interface definition of a Shiny web application.
# You can find out more about building applications with Shiny here:
# 
# http://www.rstudio.com/shiny/
 
library(shiny)
 
shinyUI(fluidPage(
  titlePanel("Mathematical Beauties: The Harmonograph"),
  sidebarLayout(
    sidebarPanel(
      #helpText(),
 
      # adding the new div tag to the sidebar            
      tags$div(class="header", checked=NA,
               tags$p("A harmonograph is a mechanical apparatus that employs pendulums to create a 
                       geometric image. The drawings created typically are Lissajous curves, or 
                       related drawings of greater complexity. The devices, which began to appear 
                       in the mid-19th century and peaked in popularity in the 1890s, cannot be 
                       conclusively attributed to a single person, although Hugh Blackburn, a professor 
                       of mathematics at the University of Glasgow, is commonly believed to be the official 
                       inventor. A simple, so-called \"lateral\" harmonograph uses two pendulums to control the movement 
                       of a pen relative to a drawing surface. One pendulum moves the pen back and forth along 
                       one axis and the other pendulum moves the drawing surface back and forth along a 
                       perpendicular axis. By varying the frequency and phase of the pendulums relative to 
                       one another, different patterns are created. Even a simple harmonograph as described 
                       can create ellipses, spirals, figure eights and other Lissajous figures (Source: Wikipedia)")),
               tags$div(class="header", checked=NA,
                       HTML("

Click <a href=\"http://paulbourke.net/geometry/harmonograph/harmonograph3.html\">here</a> to see an image of a real harmonograph

")
               ),
        actionButton('rerun','Launch the harmonograph!')
    ),
    mainPanel(
      plotOutput("HarmPlot")
    )
  )
))

server.R

# This is the server logic for a Shiny web application.
# You can find out more about building applications with Shiny here:
# 
# http://www.rstudio.com/shiny/
# 
 
library(shiny)
 
CreateDS = function () 
  {
   
  f=jitter(sample(c(2,3),4, replace = TRUE))
  d=runif(4,0,1e-02)
  p=runif(4,0,pi)
  xt = function(t) exp(-d[1]*t)*sin(t*f[1]+p[1])+exp(-d[2]*t)*sin(t*f[2]+p[2])
  yt = function(t) exp(-d[3]*t)*sin(t*f[3]+p[3])+exp(-d[4]*t)*sin(t*f[4]+p[4])
  t=seq(1, 200, by=.0005)
  data.frame(t=t, x=xt(t), y=yt(t))}
 
shinyServer(function(input, output) {
    dat<-reactive({if (input$rerun) dat=CreateDS() else dat=CreateDS()})
 output$HarmPlot<-renderPlot({
   plot(rnorm(1000),xlim =c(-2,2), ylim =c(-2,2), type="n")
   with(dat(), plot(x,y, type="l", xlim =c(-2,2), ylim =c(-2,2), xlab = "", ylab = "", xaxt='n', yaxt='n', col="gray10", bty="n"))
  }, height = 650, width = 650)
})

Shiny Wool Skeins

Chaos is not a pit: chaos is a ladder (Littlefinger in Game of Thrones)

Some time ago I wrote this post to show how my colleague Vu Anh translated into Shiny one of my experiments, opening my eyes to an amazing new world. I am very proud to present you the first Shiny experiment entirely written by me.

In this case I took inspiration from another previous experiment to draw some kind of wool skeins. The shiny app creates a plot consisting of chords inside a circle. There are to kind of chords:

  • Those which form a track because they are a set of glued chords; number of tracks and number of chords per track can be selected using Number of track chords and Number of scrawls per track sliders of the app respectively.
  • Those forming the background, randomly allocated inside the circle. Number of background chords can be chosen as well in the app

There is also the possibility to change colors of chords. This are the main steps I followed to build this Shiny app:

  1. Write a simple R program
  2. Decide which variables to parametrize
  3. Open a new Shiny project in RStudio
  4. Analize the sample UI.R and server.R files generated by default
  5. Adapt sample code to my particular code (some iterations are needed here)
  6. Deploy my app in the Shiny Apps free server

Number 1 is the most difficult step, but it does not depends on Shiny: rest of them are easier, specially if you have help as I had from my colleague Jorge. I encourage you to try. This is an snapshot of the app:

Skeins2

You can play with the app here.

Some things I thought while developing this experiment:

  • Shiny gives you a lot with a minimal effort
  • Shiny can be a very interesting tool to teach maths and programming to kids
  • I have to translate to Shiny some other experiment
  • I will try to use it for my job

Try Shiny: is very entertaining. A typical Shiny project consists on two files, one to define the user interface (UI.R) and the other to define the back end side (server.R).

This is the code of UI.R:

# This is the user-interface definition of a Shiny web application.
# You can find out more about building applications with Shiny here:
#
# http://shiny.rstudio.com
#
 
library(shiny)
 
shinyUI(fluidPage(
 
  # Application title
  titlePanel("Shiny Wool Skeins"),
  HTML("

This experiment is based on <a href=\"https://aschinchon.wordpress.com/2015/05/13/bertrand-or-the-importance-of-defining-problems-properly/\">this previous one</a> I did some time ago. It is my second approach to the wonderful world of Shiny.

"),
  # Sidebar with a slider input for number of bins
  sidebarLayout(
    sidebarPanel(
      inputPanel(
        sliderInput("lin", label = "Number of track chords:",
                    min = 1, max = 20, value = 5, step = 1),
        sliderInput("rep", label = "Number of scrawls per track:",
                    min = 1, max = 50, value = 10, step = 1),
        sliderInput("nbc", label = "Number of background chords:",
                    min = 0, max = 2000, value = 500, step = 2),
        selectInput("col1", label = "Track colour:",
                    choices = colors(), selected = "darkmagenta"),
        selectInput("col2", label = "Background chords colour:",
                    choices = colors(), selected = "gold")
      )
       
    ),
 
    # Show a plot of the generated distribution
    mainPanel(
      plotOutput("chordplot")
    )
  )
))

And this is the code of server.R:

# This is the server logic for a Shiny web application.
# You can find out more about building applications with Shiny here:
#
# http://shiny.rstudio.com
#
library(ggplot2)
library(magrittr)
library(grDevices)
library(shiny)
 
shinyServer(function(input, output) {
 
  df<-reactive({ ini=runif(n=input$lin, min=0,max=2*pi) 

  data.frame(ini=runif(n=input$lin, min=0,max=2*pi), 
             end=runif(n=input$lin, min=pi/2,max=3*pi/2))  -> Sub1

    Sub1=Sub1[rep(seq_len(nrow(Sub1)), input$rep),]
    Sub1 %>% apply(c(1, 2), jitter) %>% as.data.frame() -> Sub1
    Sub1=with(Sub1, data.frame(col=input$col1, x1=cos(ini), y1=sin(ini), x2=cos(end), y2=sin(end)))
    Sub2=runif(input$nbc, min = 0, max = 2*pi)
    Sub2=data.frame(x=cos(Sub2), y=sin(Sub2))
    Sub2=cbind(input$col2, Sub2[(1:(input$nbc/2)),], Sub2[(((input$nbc/2)+1):input$nbc),])
    colnames(Sub2)=c("col", "x1", "y1", "x2", "y2")
    rbind(Sub1, Sub2)
  })
   
  opts=theme(legend.position="none",
             panel.background = element_rect(fill="white"),
             panel.grid = element_blank(),
             axis.ticks=element_blank(),
             axis.title=element_blank(),
             axis.text =element_blank())
   
  output$chordplot<-renderPlot({
    p=ggplot(df())+geom_segment(aes(x=x1, y=y1, xend=x2, yend=y2), colour=df()$col, alpha=runif(nrow(df()), min=.1, max=.3), lwd=1)+opts;print(p)
  }, height = 600, width = 600 )
})