Add labels to plot for specific values in R

问题

I create a plot with the following dataset and I would like to add a label only for points flagged with a T in the "DisplayName" column.

Probe   Name    DisplayName X   Y
bob1    A   0   53.989643   7935.185
bob2    B   T   55.11423    7930.626
bob3    C   0   49.537724   6901.7715
bob4    D   0   57.280113   6687.0156
bob5    E   T   7.5517325   840.3756
bob6    F   0   62.68943    6666.6665
bob7    G   T   32.553364   3036.508
bob8    H   0   34.120102   2553.5354
bob9    I   0   127.54777   7818.89

My idea would be to use text() and which() to add the value of "Name" but I am stuck with something like this:

plot(data$X, data$Y)
text(data$X, data$Y, d$Name[which(d$DisplayName =="T",  arr.ind=TRUE)])

Any help will be appreciated,

Cheers ;)

回答1:

You can combine subset() and with() to use only part of data frame for function text().

plot(df$X, df$Y)
with(subset(df,DisplayName=="T"),text(X,Y,Name))

回答2:

You can do this most simply (but perhaps not as elegantly as Didzis' answer) as follows:

plot(data$X, data$Y)
text(data$X[d$DisplayName =="T"], data$Y[d$DisplayName =="T"], d$Name[d$DisplayName =="T"])

来源：https://stackoverflow.com/questions/17174090/add-labels-to-plot-for-specific-values-in-r