# The Ex Libris Generator

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:

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.

# Amazing Things That Happen When You Toss a Coin 12 Times

If there is a God, he’s a great mathematician (Paul Dirac)

Imagine you toss a coin 12 times and you count how many heads and tails you are obtaining after each throwing (the coin is equilibrated so the probability of head or tail is the same). At some point, it can happen that number of heads and number of tails are the same. For example, if you obtain the sequence T-H-T-T-H-T-H-H-T-T-H-H, after the second throwing, number of heads is equal to number of tails (and both equal to one). It happens again after the 8th throwing and after last one. In this example, the last throwing where equallity occurs is the number 12. Obviously, equallity can only be observed in even throwings.

If you repeat the experiment 10.000 times you will find something like this if you draw the relative frequency of the last throwing where cumulated number of heads is equal to the one of tails:

From my point of view there are three amazing things in this plot:

1. It is symmetrical, so prob(n)=prob(12-n)
2. The least likely throwing to obtain the last equality is the central one.
3. As a corollary, the most likely is not obtaining any equality (number of heads never are the same than number of tails) or obtaining last equality in the last throwing: two extremely different scenarios with the same chances to be observed.

Behind the simplicity of tossing coins there is a beautiful universe of mathematical surprises.

library(dplyr)
library(ggplot2)
library(scales)
tosses=12
iter=10000
results=data.frame(nmax=numeric(0), count=numeric(0), iter=numeric(0))
tmp=data.frame(nmax=numeric(0))
for (j in 1:iter)
{
data.frame(x=sample(c(-1,1), size=tosses, replace=TRUE)) %>%
mutate(cumsum = cumsum(x)) %>% filter(cumsum==0) %>%
summarize(nmax=max(as.numeric(n))) %>% rbind(tmp)->tmp
}
tmp %>%
group_by(nmax) %>%
summarize(count=n()) %>%
mutate(nmax=ifelse(is.finite(nmax), nmax, 0), iter=iter) %>%
rbind(results)->results
opts=theme(
panel.background = element_rect(fill="darkolivegreen1"),
panel.border = element_rect(colour="black", fill=NA),
axis.line = element_line(size = 0.5, colour = "black"),
axis.ticks = element_line(colour="black"),
panel.grid.major = element_line(colour="white", linetype = 1),
panel.grid.minor = element_blank(),
axis.text.y = element_text(colour="black"),
axis.text.x = element_text(colour="black"),
text = element_text(size=20),
legend.key = element_blank(),
plot.title = element_text(size = 30)
)
ggplot(results, aes(x=nmax, y=count/iter)) +
geom_line(size=2, color="green4")+
geom_point(size=8, fill="green4", colour="darkolivegreen1",pch=21)+
scale_x_continuous(breaks = seq(0, tosses, by=2))+
scale_y_continuous(labels=percent, limits=c(0, .25))+
labs(title="What happens when you toss a coin 12 times?",
x="Last throwing where cumulated #tails = #heads",
y="Probability (estimated)")+opts


# Women in Orchestras

I believe in the truth of fairy-tales more than I believe in the truth in the newspaper (Lotte Reiniger)

In my opinion, this graph is a visual demonstration that we live in a male chauvinist world.

In this experiment I download the members of ten top orchestras of the world with the amazing rvest package. After cleaning texts, I obtain the gender of names with genderizeR package as I did here. Since I only take into account names genderized with high probability, these numbers cannot be exact. Apart of this, the plot speaks by itself.

setwd("YOUR WORKING DIRECTORY HERE")
library(rvest)
library(dplyr)
library(genderizeR)
html_nodes(".name") %>%
html_text(trim=TRUE) %>%
iconv("UTF-8") %>%
gsub("[\r,\n]"," ", .) %>%
gsub("\\s+", " ", .) %>%
paste(collapse=" ") %>%
findGivenNames() -> berliner
saveRDS(berliner, file="berliner.RDS")
html_text(trim=TRUE) %>%
iconv("UTF-8") %>%
gsub("\\s+", " ", .) %>%
paste(collapse=" ") %>%
findGivenNames() -> rco
saveRDS(rco, file="rco.RDS")
html_nodes(".td") %>%
html_text(trim=TRUE) %>%
iconv("UTF-8") %>%
gsub("[\r,\n]"," ", .) %>%
gsub("\\s+", " ", .) %>%
.[23] %>%
findGivenNames() -> spb
saveRDS(spb, file="spb.RDS")
html_nodes(".col-main") %>%
html_text(trim=TRUE) %>%
iconv("UTF-8") %>%
gsub("[\r,\n]"," ", .) %>%
gsub("\\s+", " ", .) %>%
gsub("([[:lower:]])([[:upper:]][[:lower:]])", "\\1 \\2", .) %>%
findGivenNames() -> one
saveRDS(one, file="one.RDS")
html_nodes("#content") %>%
html_text(trim=TRUE) %>%
iconv("UTF-8") %>%
gsub("[\r,\n]"," ", .) %>%
gsub("\\s+", " ", .) %>%
findGivenNames() -> leipzig
saveRDS(leipzig, file="leipzig.RDS")
html_nodes(".ModSuiteMembersC") %>%
html_text(trim=TRUE) %>%
iconv("UTF-8") %>%
gsub("[\r,\n,\t,*]"," ", .) %>%
gsub("\\s+", " ", .) %>%
gsub("([[:lower:]])([[:upper:]][[:lower:]])", "\\1 \\2", .) %>%
paste(collapse=" ") %>%
.[-18] %>%
findGivenNames() -> wiener
saveRDS(wiener, file="wiener.RDS")
html_nodes(".view-content") %>%
html_text(trim=TRUE) %>%
iconv("UTF-8") %>%
gsub("\\s+", " ", .) %>%
gsub("(?%
.[1] %>%
findGivenNames() -> laphil
saveRDS(laphil, file="laphil.RDS")
html_nodes(".resp-tab-content-active") %>%
html_text(trim=TRUE) %>%
iconv("UTF-8") %>%
gsub("[\r,\n]"," ", .) %>%
gsub("\\s+", " ", .) %>%
gsub("(?%
findGivenNames() -> nyphil
saveRDS(nyphil, file="nyphil.RDS")
urls=c("http://lso.co.uk/orchestra/players/strings.html",
"http://lso.co.uk/orchestra/players/woodwind.html",
"http://lso.co.uk/orchestra/players/brass.html",
"http://lso.co.uk/orchestra/players/percussion-harps-and-keyboards.html")
sapply(urls, function(x)
{
html_nodes(".clearfix") %>%
html_text(trim=TRUE) %>%
iconv("UTF-8") %>%
gsub("[\r,\n,\t,*]"," ", .) %>%
gsub("\\s+", " ", .)
}) %>% paste(., collapse=" ") %>%
findGivenNames() -> lso
saveRDS(lso, file="lso.RDS")
html_nodes("#content-column") %>%
html_text(trim=TRUE) %>%
iconv("UTF-8") %>%
gsub("[\r,\n]"," ", .) %>%
gsub("\\s+", " ", .) %>%
findGivenNames() -> osm
saveRDS(osm, file="osm.RDS")
rbind(c("berliner", "Berliner Philharmoniker"),
c("rco", "Royal Concertgebouw Amsterdam"),
c("spb", "St. Petersburg Philharmonic Orchestra"),
c("one", "Orquesta Nacional de España"),
c("leipzig", "Gewandhaus Orchester Leipzig"),
c("wiener", "Wiener Philarmoniker"),
c("laphil", "The Los Angeles Philarmonic"),
c("nyphil", "New York Philarmonic"),
c("lso", "London Symphony Orchestra"),
c("osm", "Orchestre Symphonique de Montreal")) %>% as.data.frame()-> Orchestras
colnames(Orchestras)=c("Id", "Orchestra")
list.files(getwd(),pattern = ".RDS") %>%
lapply(function(x)
readRDS(x) %>% as.data.frame(stringsAsFactors = FALSE) %>% cbind(Id=gsub(".RDS", "", x))
) %>% do.call("rbind", .) -> all
all %>% mutate(probability=as.numeric(probability)) %>%
filter(probability > 0.9 & count > 15) %>%
filter(!name %in% c("viola", "tuba", "harp")) %>%
group_by(Id, gender) %>%
summarize(Total=n())->all
all %>% filter(gender=="female") %>% mutate(females=Total) %>% select(Id, females) -> females
all %>% group_by(Id) %>% summarise(Total=sum(Total)) -> total
inner_join(total, females, by = "Id") %>% mutate(po_females=females/Total) %>%
inner_join(Orchestras, by="Id")-> df
library(ggplot2)
library(scales)
opts=theme(legend.position="none",
plot.background = element_rect(fill="gray85"),
panel.background = element_rect(fill="gray85"),
panel.grid.major.y=element_blank(),
panel.grid.major.x=element_line(colour="white", size=2),
panel.grid.minor=element_blank(),
axis.title = element_blank(),
axis.line.y = element_line(size = 2, color="black"),
axis.text = element_text(colour="black", size=18),
axis.ticks=element_blank(),
plot.title = element_text(size = 35, face="bold", margin=margin(10,0,10,0), hjust=0))
ggplot(df, aes(reorder(Orchestra, po_females), po_females)) +
geom_bar(stat="identity", fill="darkviolet", width=.5)+
scale_y_continuous(labels = percent, expand = c(0, 0), limits=c(0,.52))+
geom_text(aes(label=sprintf("%1.0f%%", 100*po_females)), hjust=-0.05, size=6)+
ggtitle(expression(atop(bold("Women in Orchestras"), atop("% of women among members", "")))) +
coord_flip()+opts


# The Gender of Big Data

When I grow up I want to be a dancer (Carmen, my beautiful daughter)

The presence of women in positions of responsibility inside Big Data companies is quite far of parity: while approximately 5o% of world population are women, only 7% of CEOs of Top 100 Big Data Companies are.

To do this experiment, I did some webscraping to download the list of big data companies from here. I also used a very interesting package called genderizeR, which makes gender prediction based on first names (more info here).

Here you have the code:

library(rvest)
library(stringr)
library(dplyr)
library(genderizeR)
library(ggplot2)
c(., paste0("http://www.crn.com/slide-shows/data-center/300076709/2015-big-data-100-data-management.htm/pgno/0/",1:30)) %>%
c(., paste0("http://www.crn.com/slide-shows/data-center/300076740/2015-big-data-100-infrastructure-tools-and-services.htm/pgno/0/",1:25)) -> webpages
results=data.frame()
for(x in webpages)
{
read_html(x) %>% html_nodes("p:nth-child(1)") %>% .[[2]] %>% html_text() -> Company
read_html(x) %>% html_nodes("p:nth-child(2)") %>% .[[1]] %>% html_text() -> Executive
results=rbind(results, data.frame(Company, Executive))
}
results=data.frame(lapply(results, as.character), stringsAsFactors=FALSE)
results[74,]=c("Trifacta", "Top Executive: CEO Adam Wilson")
results %>% mutate(Name=gsub("Top|\\bExec\\S*|\\bCEO\\S*|President|Founder|and|Co-Founder|\\:", "", Executive)) %>%
mutate(Name=word(str_trim(Name))) -> results
results %>%
select(Name) %>%
findGivenNames() %>%
filter(probability > 0.9 & count > 15) %>%
as.data.frame() -> data
data %>% group_by(gender) %>% summarize(Total=n()) -> dat
doughnut=gvisPieChart(dat,
options=list(
width=450,
height=450,
legend="{ position: 'bottom', textStyle: {fontSize: 10}}",
chartArea="{left:25,top:50}",
title='TOP 100 BIG DATA COMPANIES 2015
Gender of CEOs (Source: crn.com)',
colors="['red','blue']",
pieHole=0.5),
chartid="doughnut")
plot(doughnut)


# The Unbereable Insolence of Prime Numbers or (Playing to be Ulam)

So rock me mama like a wagon wheel, rock me mama anyway you feel (Wagon Wheel, Old Crow Medicine Show)

This is the third iteration of Hilbert curve. I placed points in its corners. Since the curve has beginning and ending, I labeled each vertex with the order it occupies:Dark green vertex are those labeled with prime numbers and light ones with non-prime. This is the sixth iteration colored as I described before (I removed lines and labels):

Previous plot has 4.096 points. There are 564 primes lower than 4.096. What If I color 564 points randomly instead coloring primes? This is an example:

Do you see any difference? I do. Let me place both images together (on the left, the one with primes colored):

The dark points are much more ordered in the first plot. The second one is more noisy. This is my particular tribute to Stanislaw Ulam and its spiral: one of the most amazing fruits of boredom in the history of mathematics.

This is the code:

library(reshape2)
library(dplyr)
library(ggplot2)
library(pracma)
opt=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())
hilbert = function(m,n,r) {
for (i in 1:n)
{
tmp=cbind(t(m), m+nrow(m)^2)
m=rbind(tmp, (2*nrow(m))^r-tmp[nrow(m):1,]+1)
}
melt(m) %>% plyr::rename(c("Var1" = "x", "Var2" = "y", "value"="order")) %>% arrange(order)}
iter=3 #Number of iterations
df=hilbert(m=matrix(1), n=iter, r=2)
subprimes=primes(nrow(df))
df %>%  mutate(prime=order %in% subprimes,
random=sample(x=c(TRUE, FALSE), size=nrow(df), prob=c(length(subprimes),(nrow(df)-length(subprimes))), replace = TRUE)) -> df
#Labeled (primes colored)
ggplot(df, aes(x, y, colour=prime)) +
geom_path(color="gray75", size=3)+
geom_point(size=28)+
scale_colour_manual(values = c("olivedrab1", "olivedrab"))+
scale_x_continuous(expand=c(0,0), limits=c(0,2^iter+1))+
scale_y_continuous(expand=c(0,0), limits=c(0,2^iter+1))+
geom_text(aes(label=order), size=8, color="white")+
opt
#Non labeled (primes colored)
ggplot(df, aes(x, y, colour=prime)) +
geom_point(size=5)+
scale_colour_manual(values = c("olivedrab1", "olivedrab"))+
scale_x_continuous(expand=c(0,0), limits=c(0,2^iter+1))+
scale_y_continuous(expand=c(0,0), limits=c(0,2^iter+1))+
opt
#Non labeled (random colored)
ggplot(df, aes(x, y, colour=random)) +
geom_point(size=5)+
scale_colour_manual(values = c("olivedrab1", "olivedrab"))+
scale_x_continuous(expand=c(0,0), limits=c(0,2^iter+1))+
scale_y_continuous(expand=c(0,0), limits=c(0,2^iter+1))+
opt


# Going Bananas With Hilbert

It seemed that everything is in ruins, and that all the basic mathematical concepts have lost their meaning (Naum Vilenkin, Russian mathematician, regarding to the discovery of Peano’s curve)

Giuseppe Peano found in 1890 a way to draw a curve in the plane that filled the entire space: just a simple line covering completely a two dimensional plane. Its discovery meant a big earthquake in the traditional structure of mathematics. Peano’s curve was the first but not the last: one of these space-filling curves was discovered by Hilbert and takes his name. It is really beautiful:

Hilbert’s curve can be created iteratively. These are the first six iterations of its construction:

As you will see below, R code to create Hilbert’s curve is extremely easy. It is also very easy to play with the curve, altering the order in which points are sorted. Changing the initial matrix(1) by some other number, resulting curves are quite appealing:

Let’s go futher. Changing ggplot geometry from geom_path to geom_polygon generate some crazy pseudo-tessellations:

And what if you change the matrix exponent?

And what if you apply polar coordinates?

We started with a simple line and with some small changes we have created fantastical images. And all these things only using black and white. Do you want to add some colors? Try with the following code (if you draw something interesting, please let me know):

library(reshape2)
library(dplyr)
library(ggplot2)
opt=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())
hilbert = function(m,n,r) {
for (i in 1:n)
{
tmp=cbind(t(m), m+nrow(m)^2)
m=rbind(tmp, (2*nrow(m))^r-tmp[nrow(m):1,]+1)
}
melt(m) %>% plyr::rename(c("Var1" = "x", "Var2" = "y", "value"="order")) %>% arrange(order)}
# Original
ggplot(hilbert(m=matrix(1), n=1, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(1), n=2, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(1), n=3, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(1), n=4, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(1), n=5, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(1), n=6, r=2), aes(x, y)) + geom_path()+ opt
# Changing order
ggplot(hilbert(m=matrix(.5), n=5, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(0), n=5, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(tan(1)), n=5, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(3), n=5, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(-1), n=5, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(log(.1)), n=5, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(-15), n=5, r=2), aes(x, y)) + geom_path()+ opt
ggplot(hilbert(m=matrix(-0.001), n=5, r=2), aes(x, y)) + geom_path()+ opt
# Polygons
ggplot(hilbert(m=matrix(log(1)), n=4, r=2), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(.5), n=4, r=2), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(tan(1)), n=5, r=2), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(-15), n=4, r=2), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(-25), n=4, r=2), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(0), n=4, r=2), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(1000000), n=4, r=2), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(-1), n=4, r=2), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(-.00001), n=4, r=2), aes(x, y)) + geom_polygon()+ opt
# Changing exponent
gplot(hilbert(m=matrix(log(1)), n=4, r=-1), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(.5), n=4, r=-2), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(tan(1)), n=4, r=6), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(-15), n=3, r=sin(2)), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(-25), n=4, r=-.0001), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(0), n=4, r=200), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(1000000), n=3, r=.5), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(-1), n=4, r=sqrt(2)), aes(x, y)) + geom_polygon()+ opt
ggplot(hilbert(m=matrix(-.00001), n=4, r=52), aes(x, y)) + geom_polygon()+ opt
# Polar coordinates
ggplot(hilbert(m=matrix(1), n=4, r=2), aes(x, y)) + geom_polygon()+ coord_polar()+opt
ggplot(hilbert(m=matrix(-1), n=5, r=2), aes(x, y)) + geom_polygon()+ coord_polar()+opt
ggplot(hilbert(m=matrix(.1), n=2, r=.5), aes(x, y)) + geom_polygon()+ coord_polar()+opt
ggplot(hilbert(m=matrix(1000000), n=2, r=.1), aes(x, y)) + geom_polygon()+ coord_polar()+opt
ggplot(hilbert(m=matrix(.25), n=3, r=3), aes(x, y)) + geom_polygon()+ coord_polar()+opt
ggplot(hilbert(m=matrix(tan(1)), n=5, r=1), aes(x, y)) + geom_polygon()+ coord_polar()+opt
ggplot(hilbert(m=matrix(1), n=4, r=1), aes(x, y)) + geom_polygon()+ coord_polar()+opt
ggplot(hilbert(m=matrix(log(1)), n=3, r=sin(2)), aes(x, y)) + geom_polygon()+ coord_polar()+opt
ggplot(hilbert(m=matrix(-.0001), n=4, r=25), aes(x, y)) + geom_polygon()+ coord_polar()+opt


# Polar Circles

You cannot find peace by avoiding life (Virginia Woolf)

Combining polar coordinates, RColorBrewer palettes, ggplot2 and a simple trigonometric function to define the width of the tiles is easy to produce nice circular plots like these:

Do you want to try? Here you have the code:

library(ggplot2)
library(dplyr)
library(RColorBrewer)
n=500
m=50
w=sapply(seq(from=-3.5*pi, to=3.5*pi, length.out=n), function(x) {abs(sin(x))})
x=c(1)
for (i in 2:n) {x[i]=x[i-1]+1/2*(w[i-1]+w[i])}
expand.grid(x=x, y=1:m) %>%
mutate(w=rep(w, m))-> df
opt=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())
ggplot(df, aes(x=x,y=y))+geom_tile(aes(fill=x, width=w))+
coord_polar(start = runif(1, min = 0, max = 2*pi))+opt
ggplot(df, aes(x=x,y=y))+geom_tile(aes(fill=w, width=w))+
coord_polar(start = runif(1, min = 0, max = 2*pi))+opt
ggplot(df, aes(x=x,y=y))+geom_tile(aes(fill=y, width=w))+
coord_polar(start = runif(1, min = 0, max = 2*pi))+opt
ggplot(df, aes(x=x,y=y))+geom_tile(aes(fill=w*y, width=w))+
coord_polar(start = runif(1, min = 0, max = 2*pi))+opt


# Trigonometric Pattern Design

Triangles are my favorite shape, three points where two lines meet (Tessellate, Alt-J)

Inspired by recurrence plots and by the Gauss error function, I have done the following plots. The first one represents the recurrence plot of $f\left ( x \right )= sec\left ( x \right )$ where distance between points is measured by Gauss error function:

This one is the same for $f\left ( x \right )= tag\left ( x \right )$

And this one represents $latex f\left ( x \right )= sin\left ( x \right )$

I like them: they are elegant, attractive and easy to make. Try your own functions. One final though: the more I use magrittr package, the more I like it. This is the code for the first plot.

library("magrittr")
library("ggplot2")
library("pracma")
RecurrencePlot = function(from, to, col1, col2) {
opt = theme(legend.position  = "none",
panel.background = element_blank(),
axis.ticks       = element_blank(),
panel.grid       = element_blank(),
axis.title       = element_blank(),
axis.text        = element_blank())
seq(from, to, by = .1) %>% expand.grid(x=., y=.) %>%
ggplot( ., aes(x=x, y=y, fill=erf(sec(x)-sec(y)))) + geom_tile() +
RecurrencePlot(from = -5*pi, to = 5*pi, col1 = "black", col2= "white")


# 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:

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 )
})