如何在R中绘制线图？

Question

I am trying to use R to make an excel kind of a line plot, where my x axis is text (A,B,c..etc) and the y axis(which can be both negative and positive) are up and down columns. I want to give up a red color and down green.

I would really appreciate if anyone can help me regarding this. I have plotted this in excel but i have thousands of rows in my data and excel doesnot show all the text point in my plot.

My data looks like the following:

Name    UP  Downs
A   10  -3
B   2   -4
C   1   -1
D   4   -1
E   5   0
F   0   -1
G   6   -5
H   0   -1
I   7   -1
J   0   -1
K   0   -11
L   3   -1
M   0   -13
N   2   -1
O   0   -1
P   1   -1
Q   0   0
R   1   -1
S   0   0
T   12  -1

Answer 1

This is probably not the most elegant way to do it, but you can work it all out using with plot , points , and axis ( axis is the main one, it explains how you can change the labels on the axis): ?axis , ?plot , ?points .

First make a data frame similar to yours so I can demonstrate...

# make a data frame similar to yours
mydf <- data.frame( Name=LETTERS, 
        Up=sample.int(15,size=26,replace=T), 
        Down=-sample.int(15,size=26,replace=T) )

Now plot.

# set up a plot: x axis goes from 1 to 26,
# y limit goes from -15 to 15 (picked manually, you can work yours out
#   programmatically)
# Disable plotting of axes (axes=FALSE)
# Put in some x and y labels and a plot title (see ?plot...)
plot(0,xlim=c(1,26),ylim=c(-15,15),type='n',
     axes=FALSE,                 # don't draw axis -- we'll put it in later.
     xlab='Name',ylab='Change',  # x and y labels
     main='Ups and Downs')       #,frame.plot=T -- try if you like. ?plot.default
# Plot the 'Up' column in green (see ?points)
points(Up~Name,mydf,col='green')
# Plot the 'Down' column in red
points(Down~Name,mydf,col='red')
# ***Draw the x axis, with labels being A-Z 
#  (type in 'LETTERS' to the prompt to see what they are)
# see also ?axis
axis(1,at=1:26,labels=LETTERS)
# Draw the y axis
axis(2)

Tweak it as you wish: ?points and ?par and ?axis are particularly helpful in this respect.