Unequal facet heights

In the reprex below, the first and last panels are noticeably taller than the others (note the y axis ticks are overlapping for the remaining panels).

library(plotly)
#> Loading required package: ggplot2
#> 
#> Attaching package: 'plotly'
#> The following object is masked from 'package:ggplot2':
#> 
#>     last_plot
#> The following object is masked from 'package:stats':
#> 
#>     filter
#> The following object is masked from 'package:graphics':
#> 
#>     layout
library(plyr)
#> 
#> Attaching package: 'plyr'
#> The following objects are masked from 'package:plotly':
#> 
#>     arrange, mutate, rename, summarise

date <- rep(as.Date(1:365,origin='2011-1-1'),7)
location <- factor(rep(1:7,365))
product <- rep(letters[1:7], each=365)
value <- c(sample(1:10, size=365, replace=T),
           sample(1:3, size=365, replace=T),
           sample(10:100, size=365, replace=T), 
           sample(1:50, size=365, replace=T),
           sample(1:20, size=365, replace=T),
           sample(50:100, size=365, replace=T),
           sample(1:100, size=365, replace=T))
dat<-data.frame(date,location,product,value)

p <- ggplot(dat, aes(x=date, y=value, color=location, group=location)) +
    geom_line()+
  theme(panel.spacing.y = ggplot2::unit(1, "lines")) +
  facet_grid(product ~ ., scales = "fixed")

ggplotly(p)

(Also, the legend compresses the first few panels awkwardly, but that is a separate issue).

The problem also occurs with facet_wrap():

library(plotly)
#> Loading required package: ggplot2
#> 
#> Attaching package: 'plotly'
#> The following object is masked from 'package:ggplot2':
#> 
#>     last_plot
#> The following object is masked from 'package:stats':
#> 
#>     filter
#> The following object is masked from 'package:graphics':
#> 
#>     layout
library(plyr)
#> 
#> Attaching package: 'plyr'
#> The following objects are masked from 'package:plotly':
#> 
#>     arrange, mutate, rename, summarise

date <- rep(as.Date(1:365,origin='2011-1-1'),7)
location <- factor(rep(1:7,365))
product <- rep(letters[1:7], each=365)
value <- c(sample(1:10, size=365, replace=T),
           sample(1:3, size=365, replace=T),
           sample(10:100, size=365, replace=T), 
           sample(1:50, size=365, replace=T),
           sample(1:20, size=365, replace=T),
           sample(50:100, size=365, replace=T),
           sample(1:100, size=365, replace=T))
dat<-data.frame(date,location,product,value)

p <- ggplot(dat, aes(x=date, y=value, color=location, group=location)) +
    geom_line()+
  theme(panel.spacing.y = ggplot2::unit(1, "lines")) +
  facet_wrap(ncol = 1, vars(product), scales = "fixed")

ggplotly(p)

This issue doesn't appear to be coming from ggplot, but rather from ggplotly:

library(plotly)
#> Loading required package: ggplot2
#> 
#> Attaching package: 'plotly'
#> The following object is masked from 'package:ggplot2':
#> 
#>     last_plot
#> The following object is masked from 'package:stats':
#> 
#>     filter
#> The following object is masked from 'package:graphics':
#> 
#>     layout
library(plyr)
#> 
#> Attaching package: 'plyr'
#> The following objects are masked from 'package:plotly':
#> 
#>     arrange, mutate, rename, summarise

date <- rep(as.Date(1:365,origin='2011-1-1'),7)
location <- factor(rep(1:7,365))
product <- rep(letters[1:7], each=365)
value <- c(sample(1:10, size=365, replace=T),
           sample(1:3, size=365, replace=T),
           sample(10:100, size=365, replace=T), 
           sample(1:50, size=365, replace=T),
           sample(1:20, size=365, replace=T),
           sample(50:100, size=365, replace=T),
           sample(1:100, size=365, replace=T))
dat<-data.frame(date,location,product,value)

p <- ggplot(dat, aes(x=date, y=value, color=location, group=location)) +
    geom_line()+
  theme(panel.spacing.y = ggplot2::unit(1, "lines")) +
  facet_grid(product ~., scales = "fixed")

print(p)

^{Created on 2022-01-12 by the reprex package (v2.0.1)}

まず、提供された R reprex を ggplotly() で実行し、facet_grid() と facet_wrap() の出力を、適切なサイズの ggplot の結果と比較します。ggplotly による facet レイアウトの変換を追跡し、パネルの高さまたは間隔が不均等になる箇所を特定します。両方の例で、高さが等しいパネルが y 軸の目盛りと重ならずに描画されれば完了です。