How to use scale_x_date properly - r

Question

I am a new user in R and I hope you can help me.
setwd("C:/Users/USER/Desktop/Jorge")
agua <- read_excel("agua.xlsx")
pbi <- read_excel("PBIagro.xlsx")
str(agua);
names(agua)[2] <- "Variación";
agua[,1] <- as.Date(agua$Trimestre)
lagpbi <- lag(pbi$PBIAgropecuario, k=1)
pbi[,3]<- lagpbi; pbi <- pbi[-c(1),];
names(pbi)[3] <- "PBIlag"
growth <- ((pbi$PBIAgropecuario-pbi$PBIlag)/pbi$PBIlag)*100
Anual_growth <- data.frame(growth); Anual_growth[,2] <- pbi$Año; names(Anual_growth)[2] <- "Año"
# Plot
Agro <- ggplot(Anual_growth, aes(x=Año, y=growth)) +
geom_line(color="steelblue") +
geom_point() +
geom_text(aes(label = round(Anual_growth$growth, 1)),
vjust = "inward", hjust = "inward", size=2.5, show.legend = FALSE) +
xlab("") +
theme_ipsum() +
theme(axis.text.x=element_text(angle=60, hjust=1)) +
ylim(-9.9,13.4) +
theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
axis.line.x = element_blank(), plot.margin = unit(c(1,1,0.5,1),"cm"),
axis.line.y = element_blank(), axis.text.x=element_text(face = "bold", size=8,
angle=1,hjust=0.95,vjust=0.2),
axis.text.y = element_blank(), axis.title.y=element_blank())+
scale_x_continuous("Año", labels = as.character(Anual_growth$Año), breaks = Anual_growth$Año)
print(Agro)
The problem is that it shows all the years, but I only want pair years (in X-axis) or years with step equal to 2.
I hope you can really help me.
Thank you.
Notice that the X-axis variable is a numeric string.

Answer 1

You can add something like
scale_x_date(date_breaks = "2 years", date_labels = "%Y") to your ggplot.
This is how it looks with my data, since you haven't posted yours. I am plotting a type date on x axis.
1.
ggplot(mydata) +
aes(x = date, y = number, color = somevar) +
geom_line()
ggplot(mydata) +
aes(x = date, y = number, color = somevar) +
geom_line() +
scale_x_date(date_breaks = "1 year", date_labels = "%Y")
3.
ggplot(mydata) +
aes(x = date, y = number, color = somevar) +
geom_line() +
scale_x_date(date_breaks = "2 years", date_labels = "%Y")

Answer 2

If you want pair years and because your x-axis variable is numeric, you can specify in scale_x_continous that breaks argument should take only even numbers.
Here how you can do it using this small example:
year = 1998:2020
value = rnorm(23,mean = 3)
df = data.frame(year,value)
library(ggplot2)
ggplot(df, aes(x = year, y = value))+
geom_point()+
geom_line()+
scale_x_continuous(breaks = year[year %%2 ==0])
Reciprocally, if you want odd years, you just have to specify scale_x_continuous(breaks = year[year %%2 != 0])
So, in your code, you should write:
scale_x_continuous(breaks = Anual_growth$Año[Anual_growth$Año %%2 ==0])
Does it answer your question ?