Sys.setlocale("LC_TIME", "English")
library(ggplot2)
library(anytime)
library(tidyverse)
library(svglite)
library(Rcpp)

polls <- read.table("DE.csv", header=T, sep=",", fileEncoding="UTF-8", stringsAsFactor=F)
polls$polldate <- as.Date(anydate(polls$polldate))

spansize <- 0.50           # general smoothing parameter for trend line
nnum <- 600                 # number of points used for trendline (resolution)
startdate <- '1991-12-31'   # date of previous election
enddate <- '1992-11-03'     # (latest) date of next election

# retrieve party names from CSV
party1 <- colnames(polls)[2]
party2 <- colnames(polls)[3]
party3 <- colnames(polls)[4]

# define party colors (taken from https://en.wikipedia.org/wiki/Category:Germany_political_party_colour_templates)
col1 <- '#3333FF'
col2 <- '#E81B23'
col3 <- '#4F990C'

transp <-'55'       # transparency level of points

graph <- ggplot(polls)+
  geom_vline(xintercept = as.Date(startdate), color='#aaaaaabb')+       # vertical line (last election)
  geom_vline(xintercept = as.Date(enddate), color='#aaaaaabb')+         # vertical line (next election)
  geom_segment(aes(x=as.Date(startdate), xend=as.Date(enddate), y=50, yend=50), color='#666666bb', linetype='dashed')+      # horizontal line (election threshold 5%)
  # add poll points
  geom_point(aes(x = polldate, y = .data[[party1]]), size = 1.5, color = paste0(col1, transp), fill = paste0(col1, transp)) +
  geom_point(aes(x = polldate, y = .data[[party2]]), size = 1.5, color = paste0(col2, transp), fill = paste0(col2, transp)) +
  geom_point(aes(x = polldate, y = .data[[party3]]), size = 1.5, color = paste0(col3, transp), fill = paste0(col3, transp)) +
  # add trend lines
  # the "span" (smoothing parameter) should be manually changed for individual parties that have less polling data
  geom_smooth(aes(x = polldate, y = .data[[party1]]), method = "loess", span = spansize, n = nnum, se = FALSE, color = col1) +
  geom_smooth(aes(x = polldate, y = .data[[party2]]), method = "loess", span = spansize, n = nnum, se = FALSE, color = col2) +
  geom_smooth(aes(x = polldate, y = .data[[party3]]), method = "loess", span = spansize, n = nnum, se = FALSE, color = col3) +
  scale_y_continuous(labels = function(x) paste0(x, "%"), limits=c(0,69))+    # add %, manual limits on y-axis
  scale_x_date(limits = as.Date(c(startdate,enddate)), date_minor_breaks = "1 months", date_breaks = "3 months", date_labels = "%b %Y")+    # grid: 1 month, labels: 3 months
  labs(x = "", y = "")+
  scale_color_manual(name="",
                     breaks = c('col1','col2','col3'),
                     labels = c(party1,party2,party3),
					 values = c('col1'=col1,'col2'=col2,'col3'=col3))+
  # legend appearance
  theme(
    axis.text.x = element_text(size = 11),
    axis.text.y = element_text(size = 12),
    axis.title.y = element_text(size = 16),
    legend.position="right",
    legend.key.width=unit(24, "pt"),
    legend.key.height=unit(24, "pt"),
    legend.text = element_text(size=16, margin = margin(b = 5, t = 5, unit = "pt")))

graph + theme()

ggsave(file="polls.svg", plot=graph, width=18, height=8)

# workaround since svglite doesn't properly work in Wikipedia
aaa=readLines("polls.svg",-1)
bbb <- gsub(".svglite ", "", aaa)
writeLines(bbb,"polls.svg")

polldate,Clinton,Bush,Perot
12/30/1991,47,48,
2/9/1992,38,53,
2/20/1992,43,53,
3/12/1992,44,50,
3/22/1992,43,52,
3/29/1992,31,44,16
4/1/1992,25,44,24
4/23/1992,28,38,23
4/22/1992,26,41,25
5/10/1992,29,35,30
5/19/1992,27,35,30
5/20/1992,25,35,35
6/8/1992,25,31,39
6/10/1992,25,33,37
6/14/1992,24,32,34
6/20/1992,24,32,30
6/30/1992,27,33,32
7/7/1992,28,31,33
7/8/1992,28,35,30
7/11/1992,30,33,25
7/13/1992,35,31,24
7/14/1992,40,31,20
7/18/1992,56,34,
7/19/1992,58,29,
7/19/1992,63,33,
7/24/1992,56,36,
8/2/1992,57,32,
8/12/1992,58,35,
8/17/1992,58,35,
8/17/1992,51,35,
8/18/1992,51,40,
8/19/1992,48,43,
8/22/1992,52,42,
8/30/1992,56,36,
9/1/1992,50,45,
9/2/1992,54,39,
9/6/1992,48,43,
9/15/1992,51,42,
9/20/1992,50,40,
9/30/1992,52,35,7
10/4/1992,48,35,9
10/4/1992,53,36,9
10/5/1992,48,34,9
10/5/1992,46,32,10
10/8/1992,49,34,10
10/15/1992,47,34,13
10/21/1992,47,28,19
10/21/1992,45,31,20
10/22/1992,42,34,20
10/22/1992,46,32,18
10/22/1992,38,31,17
10/22/1992,43,31,18
10/23/1992,42,37,17
10/23/1992,42,30,22
10/31/1992,43,36,15
10/23/1992,42,38,16
11/1/1992,44,36,14