data visualization – How to build a trendline on a graph in R

data visualization – How to build a trendline on a graph in R

since you had some data points missing, I took what you had provided: the six points.

edit – now the full example was available

  1. A trendline is just a regression, and regressions are run most simple way like this:
    a<-lm(outcome~predictor) — in this example the object a will hold your regression parameters. To get the values of your new trendline model, just use predict(model_name), or in your case predict(a)

  2. Adding line to a plot is dead simple. Just say lines(b), where b specifies the line you want to plot after you have used the plot() function.

To wrap it up:

[![myds <- c(23.0415,13.1965,10.4110,12.2560,9.5910,10.7160,9.9665,8.5845,8.9855,8.8920,10.3425,9.3820,9.0860,9.6870,8.5635,9.0755,8.5960,7.9485,8.3235,8.1910)
x <- (1:length(myds))
plot(myds)

#make the main plot
plot(x,myds,ylim=c(5,30),xlim=c(0,20))

#add linear trend
lines(predict(lm(myds~x)),col=green)

#one more trend
lines(predict(lm(myds~log(x))),col=red)][1]][1] 

resulting

Since you have not provided reproducible examples, Ill post some links, which I think might help you:

An example for a simple, linear trend line is here:
http://www.r-tutor.com/elementary-statistics/quantitative-data/scatter-plot

Furthermore, there has been a thread on this over at SO:
How do I add different trend lines in R?

Using ggplot would make it a bit easier, as you can use the smooth functions.

data visualization – How to build a trendline on a graph in R

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