Advent of Code 2019 challenge with R

This article is originally published at https://tomaztsql.wordpress.com

I have decided to tackle this year’s Advent Of Code using R (more or less). I know there are more preferred languages, such as Python, C#, Java, JavaScript, Go, Kotlin, C++, Elixir, but it was worth trying.

Into the 8th day of the competition, in the time of writing this blog post, I have had little problems using R. There was a competition on second day, that initiated the array of arrays with 0-based first position, and knowing that R is 1-based first position, I had some fun (and aggravation) finding out the problem. And at the end, I rewrote everything in Python The same set of instructions continued on the 5th and 6th day, but R should also be just as good as any other language.

On the day 3, the Manhattan distance (similar to Manhattan wiring) from starting point to closest intersection of two different wires needed to be calculated. Which of course, it was fun, but an extra little tickle was to visualize both wires in 2-D space.

The following dataset is, the dataset I have received, your’s will be different. And the code was just a product of 10 minutes writing (hence, not really optimized).

My dataset is presented as:

library(ggplot2)
# read instructions for both wires
d <- c("R1007","D949","R640","D225","R390","D41","R257","D180","L372","U62","L454","U594","L427","U561","R844","D435","L730","U964","L164","U342","R293","D490","L246","U323","L14","D366","L549","U312","L851","U959","L255","U947","L179","U109","R850","D703","L310","U175","L665","U515","R23","D633","L212","U650","R477","U131","L838","D445","R999","D229","L772","U716","L137","U355","R51","D565","L410","D493","L312","U623","L846","D283","R980","U804","L791","U918","L641","U258","R301","U727","L307","U970","L748","U229","L225","U997","L134","D707","L655","D168","L931","D6","R36","D617","L211","D453","L969","U577","R299","D804","R910","D898","R553","U298","L309","D912","R757","U581","R228","U586","L331","D865","R606","D163","R425","U670","R156","U814","L168","D777","R674","D970","L64","U840","L688","U144","L101","U281","L615","D393","R277","U990","L9","U619","L904","D967","L166","U839","L132","U216","R988","U834","R342","U197","L717","U167","L524","U747","L222","U736","L149","D156","L265","U657","L72","D728","L966","U896","R45","D985","R297","U38","R6","D390","L65","D367","R806","U999","L840","D583","R646","U43","L731","D929","L941","D165","R663","U645","L753","U619","R60","D14","L811","D622","L835","U127","L475","D494","R466","U695","R809","U446","R523","D403","R843","U715","L486","D661","L584","U818","L377","D857","L220","U309","R192","U601","R253","D13","L95","U32","L646","D983","R13","U821","L1","U309","L425","U993","L785","U804","L663","U699","L286","U280","R237","U388","L170","D222","L900","U204","R68","D453","R721","U326","L629","D44","R925","D347","R264","D767","L785","U249","R989","D469","L446","D384","L914","U444","R741","U90","R424","U107","R98","U20","R302","U464","L808","D615","R837","U405","L191","D26","R661","D758","L866","D640","L675","U135","R288","D357","R316","D127","R599","U411","R664","D584","L979","D432","R887","D104","R275","D825","L338","D739","R568","D625","L829","D393","L997","D291","L448","D947","L728","U181","L137","D572","L16","U358","R331","D966","R887","D122","L334","D560","R938","D159","R178","D29","L832","D58","R37")
d2 <- c("L993","U121","L882","U500","L740","D222","R574","U947","L541","U949","L219","D492","R108","D621","L875","D715","R274","D858","R510","U668","R677","U327","L284","U537","L371","U810","L360","U333","L926","D144","R162","U750","L741","D360","R792","D256","L44","D893","R969","D996","L905","D524","R538","U141","R70","U347","L383","U74","R893","D560","L39","U447","L205","D783","L244","D40","R374","U507","L946","D934","R962","D138","L584","U562","L624","U69","L77","D137","L441","U671","L849","D283","L742","D459","R105","D265","R312","D734","R47","D369","R676","D429","R160","D814","L881","D830","R395","U598","L413","U817","R855","D377","L338","D413","L294","U321","L714","D217","L15","U341","R342","D480","R660","D11","L192","U518","L654","U13","L984","D866","R877","U801","R413","U66","R269","D750","R294","D143","R929","D786","R606","U816","L562","U938","R484","U32","R136","U30","L393","U209","L838","U451","L387","U413","R518","D9","L847","D605","L8","D805","R348","D174","R865","U962","R926","U401","R445","U720","L843","U785","R287","D656","L489","D465","L192","U68","L738","U962","R384","U288","L517","U396","L955","U556","R707","U329","L589","U604","L583","U457","R545","D504","L521","U711","L232","D329","L110","U167","R311","D234","R284","D984","L778","D295","R603","U349","R942","U81","R972","D505","L301","U422","R840","U689","R225","D780","R379","D200","R57","D781","R166","U245","L865","U790","R654","D127","R125","D363","L989","D976","R993","U702","L461","U165","L747","U656","R617","D115","L783","U187","L462","U838","R854","D516","L978","U846","R203","D46","R833","U393","L322","D17","L160","D278","R919","U611","L59","U709","L472","U871","L377","U111","L612","D177","R712","U628","R858","D54","L612","D303","R205","U430","R494","D306","L474","U848","R816","D104","L967","U886","L866","D366","L120","D735","R694","D335","R399","D198","R132","D787","L749","D612","R525","U163","R660","U316","R482","D412","L376","U170","R891","D202","R408","D333","R842","U965","R955","U440","L26","U747","R447","D8","R319","D188","L532","D39","L863","D599","R307","U253","R22")

Creating two empty dataframes (each for different group) and a helper function to decode the instructions: R1007 -> should be undestood as Right for 1007 steps and in accordance, the coordinates change.

gCoord2 <- function(pos, prevX, prevY){
direction <- substring(pos,1,1)
val <- as.integer(substring(pos,2,nchar(pos)))
#a <- c(0,0)
if (direction == "R") {
a <- c(prevX,prevY+val) 
return(a)}
if (direction == "L") {
a <- c(prevX,prevY-val) 
return(a)}
if (direction == "U") {
a <- c(prevX+val,prevY) 
return(a)}
if (direction == "D") {
a <- c(prevX-val, prevY) 
return(a)}
}

And not to iterate through both datasets and binding them into single one:

df <- data.frame(x = c(0), y = c(0), group = 1)
df2 <- data.frame(x = c(0), y = c(0), group = 2)

for (i in 1:length(d)){
ii <- d[i] 
print(ii)
#get last value from df
X <- tail(df$x,1)
Y <- tail(df$y,1)
x1<- gCoord2(d[i],X,Y)[1]
y1<- gCoord2(d[i],X,Y)[2]
df <-rbind(df, c(x=x1, y=y1, group=1))
}

for (i in 1:length(d2)){
ii <- d2[i] 
print(ii)
#get last value from df
X <- tail(df2$x,1)
Y <- tail(df2$y,1)
x1<- gCoord2(d2[i],X,Y)[1]
y1<- gCoord2(d2[i],X,Y)[2]
df2 <-rbind(df2, c(x=x1, y=y1, group=2))
}

df3 <- rbind(df,df2)

Finally, touch of ggplot2:

ggplot(df3, aes(x = x, y = y, group = group, colour=group)) +
geom_path(size = 0.75, show.legend = FALSE) +
# theme_void() +
ggtitle('Advent Of Code 2019; Day 3 - Graph; starting point(0,0)')

And the graph with both wires:

Happy R-coding!

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