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| # Palindromic Numbers | |
| # Nathan Stephens | |
| # 1/18/2023 | |
| library(magrittr) | |
| library(ggplot2) | |
| # Reverse digits of an integer | |
| f<-function(x){ x %>% | |
| as.character %>% | |
| strsplit("") %>% | |
| unlist %>% | |
| rev %>% | |
| paste(collapse = "") %>% | |
| as.numeric | |
| } | |
| # Calculate number of iterations to achieve palindrome | |
| out<-matrix(nrow=0, ncol=3) | |
| for(x in 1000:9999){ | |
| y<-x | |
| i<-0 | |
| while(f(y)!=y){ | |
| y<-y+f(y) | |
| i<-i+1 | |
| if(i==30){i<-NA; break} | |
| } | |
| out<-rbind(out, cbind(x,y,i)) | |
| } | |
| # Organize data for plotting | |
| df<-data.frame( | |
| group=out[,1]%/%1000*1000, | |
| increment=out[,1]%%1000,out, | |
| iterations=out[,3], | |
| log10_iterations=log10(out[,3]), | |
| missing=is.na(out[,3]) | |
| ) | |
| # Plot | |
| ggplot() + | |
| geom_line(aes(increment, log10_iterations), df) + | |
| facet_grid(rows = vars(group)) + | |
| geom_vline(aes(xintercept=increment), df[df$missing,], color="tomato") + | |
| geom_vline(aes(xintercept=increment), df[is.infinite(df$log10_iterations),], color="cyan") + | |
| labs(title="Palindromic Number", | |
| subtitle="https://en.wikipedia.org/wiki/Palindromic_number", | |
| caption="(Cyan) Zero iterations; (Red) Iterations exceeded calculation") |
Author
nwstephens
commented
Jan 18, 2023
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