Plot solid lines when you have uneven values in the x axis

Question

I was trying to plot a line using ggplot but because the x values (days) are not even spaced I do not get a solid line. I tried instead of using geom_line() to use geom_smooth() but I get the lines with confidence intervals.

My data looks like this:

#df
treatment day1 day2 day4 day6 day9
1         12,7 11,1 8,7  7,4  5,9
2         13,4 11,3 8,6  6,9  5,3
3         11,3 10,5 8,9  7,6  6,2

Is it any other geometric expression or way to arrange the data to plot a solid continuous line? Thanks in advance

This type of problems generally has to do with reshaping the data. The format should be the long format and the data is in wide format. See [this post](https://stackoverflow.com/questions/2185252/reshaping-data-frame-from-wide-to-long-format) on how to reshape the data from wide to long format. — Rui Barradas, Oct 05 '21 at 06:58

score 3 · Accepted Answer · answered Oct 05 '21 at 06:53

I'm not sure what you want exactly but it can look something like the following:

library(tidyverse)

data <- tibble(treatment = 1:3,
       day1 = c(12.7, 13.4, 11.3),
       day2 = c(11.1, 11.3, 10.5),
       day4 = c(8.7, 8.6, 8.9),
       day6 = c(7.4, 6.9, 7.6),
       day9 = c(5.9, 5.3 ,6.2))

data %>% 
  pivot_longer(-treatment, names_to = "days", names_prefix = "day") %>% 
  mutate(days = as.integer(days),
         treatment = as.character(treatment)) %>% 
  ggplot(aes(days, value, color = treatment)) +
  geom_line()

If it's not the case it can be helpful if you specify the graph you hope to get (x and y variable) and the code you have run.

In the `mutate`, coerce to factor, `treatment = factor(treatment)`. — Rui Barradas, Oct 05 '21 at 06:57

score 1 · Answer 2 · answered Oct 05 '21 at 07:40

You could use melt from reshape2 package and base graphics.

d1 <- reshape2::melt(d0, id=1, variable.name = "day") |>
  transform(day=as.numeric(gsub('day', '', day))) 

plot(value ~ day, d1, type='n', main='My Plot')
by(d1, d1$treatment, \(x) lines(value ~ day, x, col=x[1, 1] + 1))
legend('topright', legend=1:3, title='Treatment', lty=1, col=2:4, cex=.8)

Data

d0 <- read.table(header=T, text='treatment day1 day2 day4 day6 day9
1         12,7 11,1 8,7  7,4  5,9
2         13,4 11,3 8,6  6,9  5,3
3         11,3 10,5 8,9  7,6  6,2', dec=',')

Thanks that type of plot I was looking for – Gonzalo de Quesada Oct 05 '21 at 08:33 — Gonzalo de Quesada, Oct 05 '21 at 08:33

Plot solid lines when you have uneven values in the x axis

2 Answers2