R ggplot2: remove panel spacing from strip text - r

Question

I am trying to create a barplot with two x-axis (grouped x-axis):
# read data
tmp <- read.table(text = "label CNV_x CNV_Type
17p -1 Loss
9p -1 Loss
16q 1 Gain
10p 1 Gain
8q 1 Gain
13q 1 Gain", header = T)
tmp$CNV_Type <- relevel(tmp$CNV_Type, ref = 'Loss')
# plot
ggplot(tmp, aes(x = label, y = CNV_x)) +
geom_bar(stat = 'identity') +
theme_bw() +
geom_hline(yintercept = 0) +
coord_flip() +
facet_wrap(~CNV_Type, strip.position = "bottom", scales = "free_x") +
theme(panel.spacing = unit(0, "lines"),
strip.background = element_blank(),
strip.placement = "outside",
panel.border = element_rect(colour = NA))
This creates a plot like this:
This plot shows 0.00 twice on x-axis and I can't figure out a way to remove the spacing between the two vertical lines separating the strips (one is Gain and other is Loss).
Any help would be much appreciated. Thanks!
UPDATE: I added scale_y_continuous(expand = c(0, 0)) as suggested below:
ggplot(tmp, aes(x = label, y = CNV_x)) +
geom_bar(stat = 'identity') +
theme_bw() +
geom_hline(yintercept = 0) +
scale_y_continuous(expand = c(0, 0)) +
coord_flip() +
facet_wrap(~CNV_Type, strip.position = "bottom", scales = "free_x") +
theme(panel.spacing = unit(0, "lines"),
strip.background = element_blank(),
strip.placement = "outside",
panel.border = element_rect(colour = NA))
This creates a plot like this:
The only issue now is there is no spacing between the bars and the left and right margins of the plot - not sure why that happened.

Answer 1

I would not use facets here. A couple of options. You could indicate the type by colour:
tmp %>%
ggplot(aes(label, CNV_x)) +
geom_col(aes(fill = CNV_Type)) +
geom_hline(yintercept = 0) +
coord_flip() +
scale_fill_manual(values = c("darkorange", "skyblue3"))
And/or add the labels for type to the plot using annotate. That requires some manual fiddling with x, y and expand to get it right:
tmp %>%
ggplot(aes(label, CNV_x)) +
geom_col() +
geom_hline(yintercept = 0) +
coord_flip() +
annotate("text",
label = c("Loss", "Gain"),
x = c(7, 7),
y = c(-0.5, 0.5)) +
scale_x_discrete(expand = c(0.1, 0.1))