Plotting several lines in one diagramm

Question

I have a time series which shows the electricity load for every 15min during one year. I already filtered to show only one specific weekday. My dataframe:

Date        Timestamp     Weekday    Load
2017-01-02  00:00:00      Monday     272
2017-01-02  00:15:00       Monday     400
2017-01-02  00:30:00       Monday     699
2017-01-02  00:45:00       Monday     764
2017-01-02  01:00:00       Monday     983
..
..
2017-01-09  00:45:00       Monday     764
2017-01-09  01:00:00       Monday     983
..
2017-12-25  23:45:00      Monday     983

Now I want to plot several line diagrams for every monday in one diagram: x axis = Timestamp y axis = Load

I tried with ggplot:

 ggplot(Loadprofile, aes(x= Timestamp, y = Load, color = Date)) + geom_line()

But this brings me following error

Error: Aesthetics must be either length 1 or the same as the data (4992): x, y, colour

That is the output, the x-axis does not look continious though?

enter image description here

Any suggestions?

Answer 1

Your problem is that you need Date to be a factor, but when it is on a Date form, ggplot takes it as a continuous variable.

I simulated some data, just to be able to do the graph, the following code is the one I used to generate the data:

library(tidyverse)
library(lubridate)


DateTimes <- seq(
  from=as.POSIXct("2017-1-02 0:00", tz="UTC"),
  to=as.POSIXct("2017-1-09 23:59", tz="UTC"),
  by="15 min"
)  

DF <- data.frame(Date = as.Date(DateTimes), timestamp = strftime(DateTimes, format="%H:%M:%S"), Weekday = weekdays(DateTimes)) %>% filter(Weekday == "Monday") %>% mutate(load = as.numeric(timestamp)*20 + -as.numeric(timestamp)^2 + rnorm(nrow(DF), sd = 1000) + (as.numeric(Date))) %>% mutate(load = ifelse(Date < ymd("2017_01_4"), load -5000, load))

Once I have done that, if I do the following:

ggplot(DF, aes(x = timestamp, y = load)) + geom_line(aes(group = as.factor(Date), color = as.factor(Date

I get the following graph

I think that is what you need, if you need more help formating the x axis and legend let me know

Cheers