R Question
Using geom_segment to create a timeline visualization
I am trying to create a chart like this one produced in the NYTimes using ggplot:
I think I'm getting close, but I'm not quite sure how to separate out some of my data so I get the right view. My data is political office holders that appear something like this:
name,year_elected,year_left,years_in_office,type,party
Person 1,1969,1969,1,Candidate,Unknown
Person 2,1969,1971,2,Candidate,Unknown
Person 3,1969,1973,4,Candidate,Unknown
Person 4,1969,1973,4,Candidate,Unknown
Person 5,1971,1974,3,Candidate,Unknown
Person 1,1971,1976,5,Candidate,Unknown
Person 2,1971,1980,9,Candidate,Unknown
Person 6,1973,1978,5,Candidate,Unknown
Person 7,1973,1980,7,Candidate,Unknown
Person 8,1975,1980,5,Candidate,Unknown
Person 9,1977,1978,1,Candidate,Unknown
And I've used the below code to get very close to this view, but I think an issue I'm running into is either drawing segments incorrectly (e.g., I don't seem to have a single segment for each candidate), or segments are overlapping/stacking. The key issue I'm running into is my list of office holders is around 60, but my chart is only drawing around 28 lines.
library(googlesheets)
library(tidyverse)
# I'm reading from a Google Spreadsheet
data <- gs_title("Council Members")
data_sj <- gs_read(ss = data, ws = "Sheet1")
ggplot(data, aes(year_elected, years_in_office)) +
geom_segment(aes(x = year_elected, y = 0,
xend = year_left, yend = years_in_office)) +
theme_minimal()
The above code gives me:
Thanks ahead of time for any pointers!
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Answer Source
If your data frame is called d, then:
- Transform it to
data.table - Add jitter to
year_electer - Add equivalent jitter to
year_left - Add group (as an example) to color your samples
Use ggrepel to add text if there are many points.
Code:
library(data.table)
library(ggplot2)
library(ggrepel)
d[, year_elected2 := jitter(year_elected)]
d[, year_left2 := year_left + year_elected2 - year_elected + 0.01]
d[, group := TRUE]
d[factor(years_in_office %/% 9) == 1, group := FALSE]
ggplot(d, aes(year_elected2, years_in_office)) +
geom_segment(aes(x = year_elected2, xend = year_left2,
y = 0, yend = years_in_office, linetype = group),
alpha = 0.8, size = 1, color = "grey") +
geom_point(aes(year_left2), color = "black", size = 3.3) +
geom_point(aes(year_left2, color = group), size = 2.3) +
geom_text_repel(aes(year_left2, label = name), ) +
scale_colour_brewer(guide = FALSE, palette = "Dark2") +
scale_linetype_manual(guide = FALSE, values = c(2, 1)) +
labs(x = "Year elected",
y = "Years on office") +
theme_minimal(base_size = 10)
Result:
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