trendline

When adding a linear model trend line to a boxplot using standard R graphics I use: boxplot(iris[,2]~iris[,1],col="LightBlue",main="Quartile1 (Rare)") modelQ1<-lm(iris[,2]~iris[,1]) abline(modelQ1,lwd=2) However, when using this in ggplot2: a <- ggplot(iris,aes(factor(iris[,1]),iris[,2])) a + geom_boxplot() + geom_smooth(method = "lm", se=FALSE, color="black", formula=iris[,2]~iris[,1]) I get the following error: geom_smooth: Only one unique x value each group.Maybe you want aes(group = 1)? And the line does not appear on my plot. The models used in both of these scenarios are identical. If

How could I add trendline to a dot graph drawn using matplotlib.scatter? martinenzinger as explained here With help from numpy one can calculate for example a linear fitting. # plot the data itself pylab.plot(x,y,'o') # calc the trendline z = numpy.polyfit(x, y, 1) p = numpy.poly1d(z) pylab.plot(x,p(x),"r--") # the line equation: print "y=%.6fx+(%.6f)"%(z[0],z[1]) 来源： https://stackoverflow.com/questions/26447191/how-to-add-trendline-in-python-matplotlib-dot-scatter-graphs