How to create a timeseries plot using facet_wrap of ggplot2 - r

Question

This is a follow up question on How to format the x-axis of the hard coded plotting function of SPEI package in R?. in my previous question, I had a single location dataset that needed to be plotted, however, in my current situation, I have dataset for multiple location (11 in total) that in needed to plot in a single figure. I tried to replicate same code with minor adjustment, however, the code do not produce the right plot. also I do not see dates break on the x-axis. Any help would be appreciated.
library(SPEI)
library(tidyverse)
library(zoo)
data("balance")
SPEI_12=spei(balance,12)
SpeiData=SPEI_12$fitted
myDate=as.data.frame(seq(as.Date("1901-01-01"), to=as.Date("2008-12-31"),by="months"))
names(myDate)= "Dates"
myDate$year=as.numeric(format(myDate$Dates, "%Y"))
myDate$month=as.numeric(format(myDate$Dates, "%m"))
myDate=myDate[,-1]
newDates = as.character(paste(month.abb[myDate$month], myDate$year, sep = "_" ))
DataWithDate = data.frame(newDates,SpeiData)
df_spei12 = melt(DataWithDate, id.vars = "newDates" )
SPEI12 = df_spei12 %>%
na.omit() %>%
mutate(sign = ifelse(value >= 0, "pos", "neg"))
SPEI12 = SPEI12%>%
spread(sign,value) %>%
replace(is.na(.), 0)
ggplot(SPEI12) +
geom_area(aes(x = newDates, y = pos), col = "blue") +
geom_area(aes(x = newDates, y = neg), col = "red") +
facet_wrap(~variable)+
scale_y_continuous(limits = c(-2.5, 2.5), breaks = -2.5:2.5) +
scale_x_discrete(breaks=c(1901,1925,1950,1975,2000,2008))+
ylab("SPEI") + ggtitle("12-Month SPEI") +
theme_bw() + theme(plot.title = element_text(hjust = 0.5, size = 16, face = "bold"))+
theme(axis.text = element_text(size=12, colour = "black"), axis.title = element_text(size = 12,face = "bold"))
Here is what the code produces- instead of area plot it is producing bar plots.

Answer 1

With geom_area I was returning an error in the fill of the plot (a superposition), so I used geom_bar.
library(SPEI)
library(tidyverse)
library(zoo)
library(reshape2)
library(scales)
data("balance")
SPEI_12=spei(balance,12)
SpeiData=SPEI_12$fitted
myDate=as.data.frame(seq(as.Date("1901-01-01"), to=as.Date("2008-12-31"),by="months"))
names(myDate)= "Dates"
myDate$year=as.numeric(format(myDate$Dates, "%Y"))
myDate$month=as.numeric(format(myDate$Dates, "%m"))
myDate=myDate[,-1]
newDates = as.character(paste(month.abb[myDate$month], myDate$year, sep = "_" ))
DataWithDate = data.frame(newDates,SpeiData)
df_spei12 = melt(DataWithDate, id.vars = "newDates" )
SPEI12 = df_spei12 %>%
na.omit() %>%
mutate(sign = ifelse(value >= 0, "pos", "neg"))
###
SPEI12_md <- SPEI12 %>%
dplyr::mutate(Date = lubridate::parse_date_time(newDates, "m_y"),
Date = lubridate::ymd(Date),
variable = as.factor(variable))
levels(SPEI12_md$variable) <- c("Indore", "Kimberley", "Albuquerque", "Valencia",
"Viena", " Abashiri", "Tampa", "São Paulo",
"Lahore", "Punta Arenas", "Helsinki")
v <- 0.1 # 0.1 it is a gap
v1 <- min(SPEI12_md$value) - v
v2 <- max(SPEI12_md$value) + v
vv <- signif(max(abs(v1), abs(v2)), 2)
ggplot2::ggplot(SPEI12_md) +
geom_bar(aes(x = Date, y = value, col = sign, fill = sign),
show.legend = F, stat = "identity") +
scale_color_manual(values = c("pos" = "darkblue", "neg" = "red")) +
scale_fill_manual(values = c("pos" = "darkblue", "neg" = "red")) +
facet_wrap(~variable) +
scale_x_date(date_breaks = "10 years",
labels = scales::date_format("%Y-%m")) + #
scale_y_continuous(limits = c(-vv, vv), breaks = c(seq(-vv-v, 0, length.out = 3),
seq(0, vv+v, length.out = 3))) +
ylab("SPEI") + ggtitle("12-Month SPEI") +
theme_bw() + theme(plot.title = element_text(hjust = 0.5, size = 16, face = "bold"),
axis.text = element_text(size=12, colour = "black"),
axis.title = element_text(size = 12,face = "bold"),
axis.text.x = element_text(angle = 90, size = 10))

Answer 2

You use scale_x_discrete() but your variable on the x-axis, newDates, seems to be a character. It could explain why nothing is print on x-axis.
If you transform newDates as numeric (as you proposed in comments)
SPEI12$newDates= as.numeric(as.character(gsub(".*_","",SPEI12$newDates)))
and use scale_x_continuous() instead of discrete, you obtain this: