Hi John,
You can try the following:
override.linetype=c("twodash","solid")
p <- ggplot(obs, aes(x = Timestamp))
p <- p + geom_line(aes(y = air_temp, colour = "Temperature", linetype
="Temperature"))
p <- p + geom_line(aes(y = rel_hum/5, colour = "Humidity",
linetype="Humidity"))
p <- p +
guides(colour=guide_legend(override.aes=list(linetype=override.linetype)))
p <- p + scale_colour_manual(values = c("blue", "red"))
p <- p + scale_linetype_manual(values = c("twodash", "solid"),guide=FALSE)
p
I searched for help and used the info I found at this link:
https://stackoverflow.com/questions/37140266/how-to-merge-color-line-style-and-shape-legends-in-ggplot
HTH,
Eric
On Thu, Oct 12, 2017 at 10:14 AM, John <miao...@gmail.com> wrote:
> Sorry let me clarify.
> If I modify the line
> p <- p + geom_line(aes(y = air_temp, colour = "Temperature"))
> by
> p <- p + geom_line(aes(y = air_temp, colour = "Temperature", linetype
> ="Temperature"))
> and
> p <- p + geom_line(aes(y = rel_hum/5, colour = "Humidity"))
> by
> p <- p + geom_line(aes(y = rel_hum/5, colour = "Humidity",
> linetype="Humidity"))
> and
> p <- p + scale_linetype_manual(values = c("twodash", "solid")),
>
> I will have two lines with different color and different line type,
>
> but I will have two legends (one with blue/red,solid, the other with two
> dash/solid, black ).
>
> How can I have only one legend with blue/two dash and red/solid?
>
>
>
>
> 2017-10-12 0:06 GMT-07:00 John <miao...@gmail.com>:
>
> > Hi,
> >
> > To my knowledge, an excellent of ggplot with a second y-axis is
> >
> > https://rpubs.com/MarkusLoew/226759
> >
> > In this example, the author uses two colors for the two lines, but the
> > line shapes are the same -- both are solid. Could each line have its own
> > color as well as its own shape? For example, can I make the red line with
> > the linetype "twodash", while the blue line with the linetype "solid"?
> > For convenience, I copied the codes as follows.
> >
> > ########
> > p <- ggplot(obs, aes(x = Timestamp))
> > p <- p + geom_line(aes(y = air_temp, colour = "Temperature"))
> >
> > # adding the relative humidity data, transformed to match roughly the
> > range of the temperature
> > p <- p + geom_line(aes(y = rel_hum/5, colour = "Humidity"))
> >
> > # now adding the secondary axis, following the example in the help file
> > ?scale_y_continuous
> > # and, very important, reverting the above transformation
> > p <- p + scale_y_continuous(sec.axis = sec_axis(~.*5, name = "Relative
> > humidity [%]"))
> >
> > # modifying colours and theme options
> > p <- p + scale_colour_manual(values = c("blue", "red"))
> > p <- p + labs(y = "Air temperature [°C]",
> > x = "Date and time",
> > colour = "Parameter")
> > p <- p + theme(legend.position = c(0.8, 0.9))
> > p
> > ########
> >
> > Thanks,
> >
> > John
> >
>
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>
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