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I can't seem to get geom_path to connect dodged points within a facet_wrap with grouped variables. The path lines remain vertical instead of connecting observations. I want to keep the points dodged as a way to show time trajectory within a treatment. Example data and ggplot script below.

df <- data.frame (Treatment  = c("Drill_Herb", "Drill_Herb", "Drill_None", "Drill_None", "Herb_None","Herb_None", "Herb_Drill", "Herb_Drill"),
                  Comparison_Combo = c("Drill_Herb_TO_Drill_None", "Drill_Herb_TO_Drill_None", "Herb_None_TO_Herb_Drill", "Herb_None_TO_Herb_Drill"),
                  Ratio = sample(1:8, 8, replace=FALSE),
                  Year = c("2017", "2021","2017", "2021","2017", "2021","2017", "2021"))

ggplot(df, aes(x=Treatment, y=Ratio, shape=str_wrap(Year,25), 
  linetype=str_wrap(Treatment))) +
  facet_wrap(~Comparison_Combo, drop = TRUE, scales = "free_x", nrow = 1) +
  geom_point(size=3.5, position=position_dodge(width=0.55))+
  geom_path(aes(group=Treatment), lwd=1, 
  position=position_dodge(width=0.55))

Output:

Image of output plot

Chad Kluender
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1 Answers1

0

Edit2:

You could create an extra column with the x-axis position in numeric way to have the values dodged. You could use two x aesthetic columns for both the layer and geom_point and geom_line. Using scale_x_continuous to have the continuous axis to dodge the values and create labels like this:

library(ggplot2)
library(stringr)
library(dplyr)

df %>%
  mutate(Treatment2 = c(0.8, 1.2, 2.8, 3.2, 1.8, 2.2, 3.8, 4.2)) %>%
  ggplot(aes(x=Treatment, y=Ratio, shape=Year, linetype=factor(Treatment))) +
  geom_point(aes(x = Treatment2), size=3.5)+
  geom_line(aes(group = Treatment, x = Treatment2)) +
  scale_x_continuous(breaks = c(1,2,3,4), labels = c("Drill_Herb", "Herb_None", "Drill_None", "Herb_Drill")) +
  facet_wrap(~Comparison_Combo, drop = TRUE, scales = "free_x", nrow = 1)

Created on 2023-01-31 with reprex v2.0.2

Edit

You should add a column that shows the combination of the points you want to connect like this:

library(ggplot2)
library(stringr)
library(dplyr)

df %>%
  mutate(Treatment2 = c(1, 2, 3, 4, 1, 2, 3, 4)) %>%
  ggplot(aes(x=Treatment, y=Ratio, shape=Year, linetype=factor(Treatment2), group = factor(Treatment2))) +
  facet_wrap(~Comparison_Combo, drop = TRUE, scales = "free_x", nrow = 1) +
  geom_point(size=3.5, position=position_dodge(width=0.55))+
  geom_path(lwd=1, 
            position=position_dodge(width=0.55))

Created on 2023-01-31 with reprex v2.0.2

You could use group in your aesthetics like this:

library(ggplot2)
library(stringr)
ggplot(df, aes(x=Treatment, y=Ratio, shape=str_wrap(Year,25), 
               linetype=str_wrap(Treatment), group = 1)) +
  facet_wrap(~Comparison_Combo, drop = TRUE, scales = "free_x", nrow = 1) +
  geom_point(size=3.5, position=position_dodge(width=0.55))+
  geom_path(aes(group=Treatment), lwd=1, 
            position=position_dodge(width=0.55))

Created on 2023-01-31 with reprex v2.0.2

Quinten
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  • The issue is that I would prefer if the points were dodged within a treatment, and the connecting line would show the time trajectory from 2017 to 2021. Exactly like in my reference figure, but the lines should connect the points, instead of being vertical. – Chad Kluender Jan 31 '23 at 18:57
  • Hi @ChadKluender, Aah I see, you need a column which shows an unique combination for your linetype. – Quinten Jan 31 '23 at 19:21
  • Hi @ChadKluender, Please see updated answer above! – Quinten Jan 31 '23 at 19:29
  • Thanks Quinten, this is still not the answer I'm looking for. I'm trying to connect the individual year symbols within the treatments within a comparison combo. For example, drill_none 2017 to drill_none 2021. We did this on the first example you created, but the point jitter was removed. It seems that every time I create a grouping variable the jitter is removed. Even when I create a unique ID for treatmentXcomparison combo – Chad Kluender Jan 31 '23 at 19:59