How to create a legend using the function "legend" if my labels are hour data?

[CesarGastello]

I have a problem. If i create a graphic using the function "plot" with time data vs temperature data and then i want make a legend with funtion "legend", i don't know what write in "x"(this define the position) because this data aren't "numeric", are "POSIXct".
What i do now?

Data

head(temp_peces)
Hora Temperatura Condición
1 1899-12-31 00:00:00 18.0 Estable
2 1899-12-31 00:30:00 18.5 Estable
3 1899-12-31 01:00:00 18.0 Estable
4 1899-12-31 01:30:00 18.0 Estable
5 1899-12-31 02:00:00 18.0 Estable
6 1899-12-31 02:30:00 18.0 Estable

type of data

lapply(temp_peces, class)
$Hora
[1] "POSIXct" "POSIXt"
$Temperatura
[1] "numeric"
$Condición
[1] "factor"

Graphics

plot(temp_peces$Hora,temp_peces$Temperatura,col=temp_peces$Condición,pch=19,main = "Temperatura diaria",xlab = "Hora",ylab = "Temperatura (°C)",cex=2)

i want make a legend, but the position in "x" are not valid

legend(x=2,y=22,legend=levels(temp_peces$Condición),col = c(1:3),pch = 19)

[andresrcs]

Hi!

To help us help you, could you please prepare a reproducible example (reprex) illustrating your issue? Please have a look at this guide, to see how to create one:

FAQ: How to do a minimal reproducible example ( reprex ) for beginners

A minimal reproducible example consists of the following items: A minimal dataset, necessary to reproduce the issue The minimal runnable code necessary to reproduce the issue, which can be run on the given dataset, and including the necessary information on the used packages. Let's quickly go over each one of these with examples: Minimal Dataset (Sample Data) You need to provide a data frame that is small enough to be (reasonably) pasted on a post, but big enough to reproduce your issue. Let's say, as an example, that you are working with the iris data frame head(iris) #> Sepal.Length Sepal.Width Petal.Length Petal.Width Species #> 1 5.1 3.5 1.4 0.…

[andresrcs]

Thanks for adding the reprex but have in minde that you are not using a copy/paste friendly format and your reprex is not self contained making it harder to help you, in case you prefer here is the spanish version of the reprex guide

About your question, you just have to use a POSIXct value for the x axis, see this example.

temp_peces <- data.frame(stringsAsFactors=FALSE,
                         Hora = as.POSIXct(c("1899-12-31 00:00:00", "1899-12-31 00:30:00",
                                  "1899-12-31 01:00:00", "1899-12-31 01:30:00",
                                  "1899-12-31 02:00:00", "1899-12-31 02:30:00")),
                         Temperatura = c(18, 18.5, 18, 18, 18, 18),
                         Condición = as.factor(c("Estable", "Estable", "Estable", "Other Value", "Other Value",
                                                 "Other Value"))
)

plot(temp_peces$Hora,
     temp_peces$Temperatura,
     col = temp_peces$Condición,
     pch = 19,
     main = "Temperatura diaria",
     xlab = "Hora",
     ylab = "Temperatura (°C)",
     cex = 2)

legend(x = as.POSIXct("1899-12-31 01:30:00"),
       y = 18.4,
       legend = levels(temp_peces$Condición),
       col = c(1:3),
       pch = 19)