Às 19:20 de 01/07/2023, Luigi Marongiu escreveu:
Hello,
I have a dataframe with measurements stratified by the concentration
of a certain substance. I would like to plot the points of the
measures and connect the points within each series of concentrations.
When I launch ggplot2 I get the error
```
geom_path: Each group consists of only one observation. Do you need to
adjust the
group aesthetic?
```
and no lines are drawn.
Where am I going wrong?
Thank you
Luigi
```
df = data.frame(Conc = c(rep(1, 3), rep(2, 3), rep(5, 3)),
Time = rep(1:3, 3),
Value = c(0.91, 0.67, 0.71, 0.91, 0.65, 0.74, 0.95, 0.67,
0.67))
df$Time <- as.factor(df$Time)
levels(df$Time) = c(1, 4, 24)
df$Conc <- as.factor(df$Conc)
levels(df$Conc) = c(1, 2, 5)
library(ggplot2)
ggplot(df, aes(x=Time, y=Value, colour=Conc)) +
geom_point(size=6) +
geom_line(aes(x=Time, y=Value, colour=Conc)) +
scale_colour_manual(values = c("darkslategray3", "darkslategray4",
"deepskyblue4")) +
ggtitle("Working example") +
xlab(expression(bold("Time (h)"))) +
ylab(expression(bold("Concentration (mM)")))
```
Hello,
Here are two solutions. I have removed the redundant aes() from
geom_line in both plots.
1. If you do not coerce Time to factor, the x axis will be continuous.
The plot will be as expected but you wi have to include a
scale_x_continuous to have the wanted labels.
df = data.frame(Conc = c(rep(1, 3), rep(2, 3), rep(5, 3)),
Time = rep(1:3, 3),
Value = c(0.91, 0.67, 0.71, 0.91, 0.65, 0.74, 0.95,
0.67, 0.67))
library(ggplot2)
df$Conc <- factor(df$Conc, levels = c(1, 2, 5))
ggplot(df, aes(x=Time, y=Value, colour=Conc)) +
geom_point(size=6) +
geom_line() +
scale_colour_manual(values = c("darkslategray3", "darkslategray4",
"deepskyblue4")) +
scale_x_continuous(breaks = 1:3, labels = c(1, 2, 24)) +
ggtitle("Working example") +
xlab(expression(bold("Time (h)"))) +
ylab(expression(bold("Concentration (mM)")))
2. Time is coerced to factor. Then, tell geom_line the data is grouped
by Conc. This is probably the solution you should use.
df$Time <- factor(df$Time, labels = c(1, 4, 24))
ggplot(df, aes(x=Time, y=Value, colour=Conc)) +
geom_point(size=6) +
geom_line(aes(group = Conc)) +
scale_colour_manual(values = c("darkslategray3", "darkslategray4",
"deepskyblue4")) +
ggtitle("Working example") +
xlab(expression(bold("Time (h)"))) +
ylab(expression(bold("Concentration (mM)")))
Hope this helps,
Rui Barradas
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