如何在R中绘制数据帧的子集？

Question

Is there a simple way to do this in R:

plot(var1,var2, for all observations in the data frame where var3 < 155)

It is possible by creating a new data newdata <- data[which( data$var3 < 155),] but then I have to redefine all the variables newvar1 <- newdata$var1 etc.

Answer 1

with(dfr[dfr$var3 < 155,], plot(var1, var2)) should do the trick.

Edit regarding multiple conditions:

with(dfr[(dfr$var3 < 155) & (dfr$var4 > 27),], plot(var1, var2))

Answer 2

Most straightforward option:

plot(var1[var3<155],var2[var3<155])

It does not look good because of code redundancy, but is ok for fast n dirty hacking.

Answer 3

This is how I would do it, in order to get in the var4 restriction:

dfr<-data.frame(var1=rnorm(100), var2=rnorm(100), var3=rnorm(100, 160, 10), var4=rnorm(100, 27, 6))
plot( subset( dfr, var3 < 155 & var4 > 27, select = c( var1, var2 ) ) )

Rgds, Rainer

Answer 4

This chunk should do the work:

plot(var2 ~ var1, data=subset(dataframe, var3 < 150))

My best regards.

How this works:

1. Fisrt, we make selection using the subset function. Other possibilities can be used, like, subset(dataframe, var4 =="some" & var5 > 10). The " & " operator can be used to select all "some" and over 10. Also the operator " | " could be used to select "some" or "over 10".
2. The next step is to plot the results of the subset, using tilde (~) operator, that just imply a formula, in this case var.response ~ var.independet. Of course this is not a formula, but works great for this case.