Scatterplot numerical y against two x groups-CodePudding

From my data, I created the following vectors:

ratio_automatic <- c(2.031, 2.24, 2.00, 0.46, 2.75, 0.86, 2.69, 0.44)
ratio_manual <- c(1.02, 2.40, 1.53, 0.50, 1.38, 0.70, 1.69, 0.54)
method <- rep(c("Manual", "Automatic"), each = 8)

to create the following dataframe:

df <- data.frame(method, c(ratio_automatic, ratio_manual))
names(df) <- c("method", "ratio")

So I think that is then called narrow data? In summary: there are 16 observations to two variables.

I want to plot the data in a scatterplot, so you can see the ratio datapoints grouped by category (either 'manual' or 'automatic'). When I run the following code:

plot(1:nrow(df), df$ratio, xaxt="n", xlab="Method", ylab="Ratio", pch=19)
axis(1, at=1:16, labels=df$method)

I get the following graph:

This is not what I want, as I want on the x-axis just 'automatic' and 'manual' and then the corresponding points above that, not each point separate like now.

is there a way to fix this?

(I'm still very new to R, so I'm sorry if this is an obvious question.)

CodePudding user response：

If you want "Automatic" and "Manual" to appear only once on the x-axis, then you shouldn't make a scatterplot. Scatterplots assumes that both your x- and y-axes are continuous. Consider making a boxplot and overlaying with jittered points, similar to what you would find in a scatterplot.

# make a boxplot
boxplot(df$ratio ~ df$method, col = "white")

# add some points
stripchart(df$ratio ~ df$method,
           method = "jitter",
           pch = 19,
           vertical = TRUE,
           add = TRUE)

CodePudding user response：

Maybe you want something like this where you start with an empty plot and then plot on the 1 and 2 of your factor methods and use points to add the data like this which results in a jitter plot ( you can adjust the positions of your labels in axis):

plot(1, type="n", xlim=c(0, 3), xaxt="n", ylim = c(0, 3), xlab="Method", ylab="Ratio", pch=19)
axis(1, at=1:2, labels=unique(df$method))
points(factor(df$method), df$ratio, xaxt="n", xlab="Method", ylab="Ratio", pch=19)

Output: