R Script ggplot Line Plot

[palvarez]

Hello,

I'm trying for the first time ever R Scripting with ggplot. However I've encountered a small roadblock. While attempting to do a line chart, why does my data plunges to 0 but lines back to the number it should be? My data doesn't behave in such way, so what am I missing? I'm truly an beginner in this topic, so it might be something dumb, however I haven't found any answers online yet.

library(ggplot2)
library(gtable)
library(grid)
#library(extrafont)

data <- dataset
mon <- data$Monto
trans <- data$Transacciones
fec <- format(as.Date(data$Fecha), "%Y/%m")

options(scipen=999)
p1 <- ggplot(data, aes(fec, mon, group = 1)) + geom_line()

p1

* Note: I've been attempting to create a visual of two y axes. That's why I'm using ggplot. I'm halfway there, but I need to get this fixed first.

[v-sihou-msft · Accepted solution]

@palvarez

Based on your code, it seems you put date field into your dataset. I assume you have data on day level. As you format your Date into "YearMonth", which means you have multiple data point on same X axis category. This the reason why your line goes crazy. 

In your scenario, you should use stat_summary() function to have those data points aggregate on each "YearMonth". Please refer to my sample below: 

library(ggplot2)
library(gtable)

df <- dataset
trans <- df$Amount
fec <- format(as.Date(df$Date), "%Y/%m")
options(scipen=999)
p1 <- ggplot() +stat_summary(aes(x=fec, y=trans,group=1), fun.y = sum, geom = "line")
p1

Regards,