direct labels

[grantmcdermott]

I needed this for a plot at work yesterday.

Not sure if we want to roll this into an explicit type (and I'm time constrained ATM regardless), but we could at least add it to the tips and tricks vignette. (Caveat: I don't think the RHS margin bump will work with themes.)

library(tinyplot)
palette("classic")

aq = airquality
aq$Month = factor(month.name[aq$Month], levels = month.name[5:9])

# for labels: subset to final dates for each month 
aq2 = aq[aq$Day == ave(aq$Day, aq$Month, FUN = max), ]

plt(
    Temp ~ Day | Month, data = aq,
    type = "l", legend = FALSE, axes = 'l', grid = TRUE
)
text(
    Temp ~ Day, data = aq2, labels = Month,
    pos = 4, offset = 0.2,
    xpd = NA, col = as.integer(Month)
)

The above is okay for shorter labels, but cuts off longer labels. We can bump the RHS margin to fix:

# bump rhs margin for longer labels
omar = par('mar')
omar[4] = omar[4] + max(strwidth(as.character(aq2$Month)))/2
op = par(mar = omar)

plt(
    Temp ~ Day | Month, data = aq,
    type = "l", legend = FALSE, axes = 'l', grid = TRUE
)
text(
    Temp ~ Day, data = aq2, labels = Month,
    pos = 4, offset = 0.2,
    xpd = NA, col = as.integer(Month)
)

par(op)

^{Created on 2025-06-17 with reprex v2.1.1}

[vincentarelbundock]

this is very nice. Yeah, I think tips and tricks would be a good place. Would our type_text() make this easier?

https://grantmcdermott.com/tinyplot/man/type_text.html

If so, it would be nice to showcase that.

[grantmcdermott]

Would our type_text() make this easier?

Yeah, I actually tried this originally with draw:

plt(
    Temp ~ Day | Month, aq, type = "l", legend = FALSE, 
    draw = plt(
        Temp ~ Day | Month, aq2,
        type = "text", add = TRUE,
        labels = aq2$Month,
        pos = 4, offset = 0.2, xpd = NA
    )
) 

The problem is that type_text() doesn't support the xpd = NA argument, so it gets ignored and the labels get clipped. (Maybe we can add support for this?)

Another minor issue is that we don't (yet) support NSE for labels = Month, but I know that this is on the roadmap (cc @zeileis ;-) )

[vincentarelbundock]

Isn't xpd a tpar() parameter? This seems to work. (except for the right margin should be extended a bit)

library(tinyplot)
tinytheme("ipsum")

aq = airquality
aq$Month = factor(month.name[aq$Month], levels = month.name[5:9])
aq2 = aq[aq$Day == ave(aq$Day, aq$Month, FUN = max), ]

tpar(xpd = NA)
plt(Temp ~ Day | Month, data = aq, type = "l", legend = FALSE)
plt_add(Temp ~ Day | Month, data = aq2,
        type = "text",
        labels = aq2$Month,
        pos = 4, offset = 0.2)

[grantmcdermott]

Yes, but note that the grid lines aren't being clipped now either. So this approach has some undesirable side effects. I think it would be best if we added xpd support directly to type_text(). Once that's done, the final "tips" entry might look something as follows:

parms = tinyplot:::theme_clean2
parms$mar[4] = parms$mar[4] + max(strwidth(as.character(aq2$Month)))/2

tinytheme("clean2", mar = parms$mar)
plt(
    Temp ~ Day | Month, aq, type = "l", legend = FALSE, 
    draw = plt(
        Temp ~ Day | Month, 
        data = aq2,
        type = "text", add = TRUE,
        labels = aq2$Month,
        pos = 4, offset = 0.2, xpd = NA
    )
) 

[zeileis]

Very nice and useful! Would this also work in combination in facets?

[vincentarelbundock]

Is there a practical difference between draw and plt_add()?

I find the latter more readable, but am curious.

[grantmcdermott]

Very nice and useful! Would this also work in combination in facets?

"Yes", but you'd have to adjust fmar rather than (in addition to?) mar if I'm not mistaken.

Is there a practical difference between draw and plt_add()?

I find the latter more readable, but am curious.

Not for this particular example and the following would work once we fix the xpd issue. (Any takers for the simple PR?)

plt(Temp ~ Day | Month, data = aq, type = "l", legend = FALSE)
plt_add(data = aq2, type = "text", labels = aq2$Month,
        pos = 4, offset = 0.2, xpd = NA)

But two important differences are: (1) draw is fully generic and accepts any drawing function (e.g., text()), not just tinyplot types. (2) draw() items are added before the first layer. So it can be useful constructing layered plots that you want to save with file (c.f. #426).

[grantmcdermott]

@zeileis Just a follow up to your facet question: I've confirmed that it does work with fmar, although we need an extra adjustment because of a scaling factor used for facets (e.g., 0.83 in a 4x4 facet case; see here).

Fancy spaghetti plot example for posterity:

aq = subset(airquality, Month > 5)
aq$Month = factor(month.name[aq$Month], levels = month.name[6:9])

# for labels: subset to final dates for each month 
aq2 = aq[aq$Day == ave(aq$Day, aq$Month, FUN = max), ]

library(tinyplot)
tinytheme("clean2", grid = FALSE)
plt(Temp ~ Day | Month, data = aq, type = "l", legend = FALSE, facet = 'by', lwd = 2,
    draw = tinyplot(Temp ~ Day | Month, aq, col = "grey", type = "l", add = TRUE))
plt_add(data = aq2, type = "text", labels = aq2$Month, font = 2,
        pos = 4, offset = 0.2, xpd = NA)

longest_lab = max(strwidth(as.character(aq2$Month)))/2/0.83
parms = tinyplot:::theme_clean2
parms$fmar = rep(1, 4)
parms$fmar[4] = parms$fmar[4] + longest_lab

tinytheme("clean2", grid = FALSE, fmar = parms$fmar) 

# Now plot both the base and direct label layers
plt(Temp ~ Day | Month, data = aq, type = "l", legend = FALSE, facet = 'by', lwd = 2,
    draw = tinyplot(Temp ~ Day | Month, aq, col = "grey", type = "l", add = TRUE))
plt_add(data = aq2, type = "text", labels = aq2$Month, font = 2,
        pos = 4, offset = 0.2, xpd = NA)
tinytheme()

[zeileis]

Nice! Maybe also something for tips and tricks?