Dear R experts,
Thank you all for your help.
Now, I know that the ggplot is causing the issue and that
setting the y=as.numeric(rslt_with_I) can fix the problem,
that should suffice for now, since I am not an R expert.
In addition, this time, I could learn that there is a class
of "AsIs", and that the ggplot might not expect the use
of "AsIs" class in the data. This is a bit of learning for me.
Thank you, again. Your responses helped me a lot.
Sincerely,
Hiroto
On 2025/04/21 6:24, peter dalgaard wrote:
What Ben says. Also a bit of pragmatic advice:
If you want people to help you and run your scripts, don't precede each line with 9
characters that they'll have to remove to make it runnable. (Emacs users can do "C-x
r k", but there aren't that many Emacs users around these days.)
Also, the script is overly complicated and expects the user to (install and)
load a bunch of stuff, where the effect that you are talking about is just as
clearly visible in simpler code like this.
ggplot(dta, aes(x = x, y = as.numeric(y)))+geom_line()
x <- 1:10; y <- rnorm(10) ; dta <- data.frame(x,y)
ggplot(dta, aes(x = x, y = y )) + geom_line()
ggplot(dta, aes(x = x, y = I(y) )) + geom_line()
However, like Ben, I'm not quite up to drilling into the ggplot code to see
where things go wrong.
Apparently, you can leave out the geom_line() bit and still get the odd y
scale, so the issue is inside ggplot() it self and perhaps you could do
something like debug(ggplot2:::ggplot_build.ggplot) and single-step and see if
you can spot where and how the y scale is being set up.
-pd
On 19 Apr 2025, at 23.15, Ben Bolker <bbol...@gmail.com> wrote:
This is obviously not a complete answer, but if you look at the data closely:
str(dta)
'data.frame': 40 obs. of 6 variables:
$ x : num 0.915 0.937 0.286 0.83 0.642 ...
$ y : num 0.3796 0.4358 0.0374 0.9735 0.4318 ...
$ z : int 1 1 1 1 1 1 1 1 1 1 ...
$ x_axis : int 1 2 3 4 5 6 7 8 9 10 ...
$ rslt_without_I: num 0.7657 0.8474 0.0516 1.1533 0.483 ...
$ rslt_with_I : 'AsIs' num 0.765658.... 0.847406.... 0.051648....
1.153295.... 0.482993.... ...
you'll see that the two variables have different *classes*. Your '==' test
checks to see if the *numeric values* of the elements are the same.
Both of these, which check the characteristics of the vector itself as well as
the values of the elements, indicate that these vectors are indeed different.
identical(dta$rslt_with_I, dta$rslt_without_I)
all.equal(dta$rslt_with_I, dta$rslt_without_I)
In order to figure out *why* having class "AsIs" rather than class "numeric" makes the
axis/breaks computation fail, you'd have to dig into the machinery (or, ask on the ggplot issues list -- the questions
there involving "AsIs" mostly refer to a separate use case for "AsIs" ...
https://github.com/tidyverse/ggplot2/issues?q=is%3Aissue%20AsIs )
On 2025-04-18 9:46 p.m., Hiroto Miyoshi wrote:
Dear R expert
I encountered a bewildering situation, about which
I am seeking help. I wrote a following toy script
which can recreate the situation.
--- the script begins here ---
1 │ library(tidyverse)
2 │ library(rlist)
3 │ library(patchwork)
4 │ set.seed(42)
5 │ f <- function(x, y, z, x_axis) {
6 │ rslt_with_I <- I(x^2 * 0.5) + I(x * y)
7 │ rslt_without_I <- (x^2 * 0.5) + (x * y)
8 │ out <- data.frame(rslt_without_I, rslt_with_I)
9 │ return(out)
10 │ }
11 │
12 │ df <- data.frame(
13 │ x = runif(40, 0, 1),
14 │ y = runif(40, 0, 1),
15 │ z = rep(1:4, rep(10, 4)),
16 │ x_axis = rep(1:10, 4)
17 │ )
18 │
19 │ dta <- pmap(df, f) %>%
20 │ list.stack(.) %>%
21 │ cbind(df, .)
22 │
23 │ g1 <- ggplot(dta, aes(x = x_axis, y = rslt_with_I, color =
factor(z))) +
24 │ geom_point() +
25 │ geom_line()
26 │ g2 <- ggplot(dta, aes(x = x_axis, y = rslt_without_I, color =
factor(z))) +
27 │ geom_point() +
28 │ geom_line()
29 │
30 │ g <- g1 | g2
31 │ plot(g)
32 │
33 │ dta$rslt_with_I == dta$rslt_without_I
34 │ # the end of the script
The two graphs, i.e. g1 and g2 are different and obviously, the data do not
fit in the graph area for g1. The command "dta$rslt_with_I ==
dta$rslt_without_I"
shows the plotted data are identical. I want why this happens.
Sincerely
Hiroto
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--
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Director, School of Computational Science and Engineering
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______________________________________________
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PLEASE do read the posting guide https://www.R-project.org/posting-guide.html
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