我有一个数据框,其值在连续时间段内在四个位置上用仪器测量。我希望将晚上的时间(下午6点至凌晨6点)涂成灰色以帮助解释。下面的代码正确地绘制了此代码,除了当仪器未在每个位置收集数据时,我也想使用facet_grid(..., scales = 'free_x')
删除不必要的时间段。
require(ggplot2)
df.long <- data.frame(Timestamp = seq.POSIXt(as.POSIXct("2018-07-05 18:00:00", format = '%Y-%m-%d %H:%M:%S'), by = 'hour', length.out = 192),
Location = c(rep('A', 48), rep('B', 48), rep('C', 48), rep('D', 48)),
value = sin(seq(1:192)/4))
shade <- data.frame(dusk = seq.POSIXt(as.POSIXct("2018-07-05 18:00:00", format = '%Y-%m-%d %H:%M:%S'), by = 'day', length.out = 8),
dawn = seq.POSIXt(as.POSIXct("2018-07-06 06:00:00", format = '%Y-%m-%d %H:%M:%S'), by = 'day', length.out = 8),
top = Inf,
bottom = -Inf)
ggplot(df.long) +
geom_rect(data = shade,
aes(xmin = dusk, xmax = dawn,ymin = bottom, ymax = top),
fill = 'light grey', alpha = 0.5) +
geom_line(aes(x = Timestamp, y = value, col = Location)) +
geom_point(aes(x = Timestamp, y = value, fill = Location), pch = 21) +
facet_grid( ~ Location, scales = 'free_x') +
ylab('Flux (mg O2 m-2 h-1)') +
theme_bw()
当我排除对facet_grid(..., scales = 'free_x')
的调用时,用geom_rect
正确缩放了X轴。我如何在第二张图上绘制阴影的geom_rect
而无需扩展X轴刻度?
ggplot(df.long) +
# geom_rect(data = shade, aes(xmin = dusk, xmax = dawn,
# ymin = bottom, ymax = top), fill = 'light grey', alpha = 0.5) +
geom_line(aes(x = Timestamp, y = value, col = Location)) +
geom_point(aes(x = Timestamp, y = value, fill = Location), pch = 21) +
facet_grid( ~ Location, scales = 'free_x') +
ylab('Flux (mg O2 m-2 h-1)') +
theme_bw() +
theme(legend.position = 'none')
我也尝试用geom_rect替换为:
annotate("rect",
xmin = shade$dusk, xmax = shade$dawn, ymin = shade$bottom, ymax = shade$top,
fill = "light grey", alpha = 0.5) +
一种可能的方法是仅为每个构面定义相关的阴影矩形:
library(dplyr)
shade2 <- shade %>%
# replicate shade for each facet
slice(rep(seq(1, n()),
times = n_distinct(df.long$Location))) %>%
mutate(Location = rep(sort(unique(df.long$Location)),
each = n()/4)) %>%
# calculate actual x-range associated with each facet, & join with shade
left_join(df.long %>%
group_by(Location) %>%
summarise(xmin = min(Timestamp),
xmax = max(Timestamp)) %>%
ungroup(),
by = "Location") %>%
# for each shade facet, keep only rows within relevant x-range
filter(dusk >= xmin & dawn <= xmax)
ggplot(df.long) +
geom_rect(data = shade2, # replace shade with shade2, everything else is unchanged
aes(xmin = dusk, xmax = dawn,
ymin = bottom, ymax = top),
fill = 'light grey', alpha = 0.5) +
geom_line(aes(x = Timestamp, y = value, col = Location)) +
geom_point(aes(x = Timestamp, y = value, fill = Location), pch = 21) +
facet_grid( ~ Location, scales = 'free_x') +
ylab('Flux (mg O2 m-2 h-1)') +
theme_bw()