Plot dataframe in R in a for loop

Question

Say I have a dataframe named as "data":

Sal T1  T2  T3  T4  T5  T6
29.0    4.00    NA  NA  NA  NA  NA
29.5    7.50    NA  NA  NA  NA  NA
30.0    10.40   1.50    NA  NA  NA  NA
30.5    12.50   6.00    NA  NA  NA  NA
31.0    14.50   9.00    NA  NA  NA  NA
31.5    16.25   11.50   4.00    NA  NA  NA
32.0    18.00   13.50   7.50    NA  NA  NA
32.5    19.50   15.25   10.00   1.50    NA  NA
33.0    20.90   17.00   12.20   5.55    NA  NA
33.5    22.40   18.50   14.10   8.50    NA  NA
34.0    23.60   20.00   16.05   11.00   4.0 NA
34.5    24.90   21.50   17.50   13.00   7.1 NA
35.0    NA  22.75   19.20   14.70   9.7 1.5
35.5    NA  23.90   20.50   16.50   11.9    5.5

I need to plot all columns with respect to column 1 in one graph. I can do it one by one by adding points and lines to the initial plot. For example:

mydata1 = na.omit(data[1:2])
plot(mydata1)
lines(mydata1,col=1)
mydata2 = na.omit(data.frame(c(data[1]),c(data[3])))
points(mydata2, col =2)
lines(mydata2,col=2)

But it is too tedious. I am thinking using for loop to plot all at once. But it seems only plotting the last one:

for (i in 2:ncol(data)){
  mydata = na.omit(data.frame(c(data[1]),c(data[i])))
  plot(mydata)
  lines(mydata)
}

How do I do this in R? Thanks for any help.

Here is the final solution:

plot(0,0,xlim=c(28,37),ylim=c(0,25),type="n",ylab = "T", xlab = "Sal")

for (i in 2:ncol(data)){
  mydata = na.omit(data.frame(c(data[1]),c(data[i])))
  lines(mydata, col = i)
  legendN = colnames(data)
  legendN = legendN[2:7]
  legend("topleft", legend = legendN, col= 2:7, pch=1) # optional legend
}

Maybe throw plot() outside the loop? Lines and points leave in the loop. — John_West
– John_West, Commented Mar 1, 2016 at 18:32

Philip · Accepted Answer · 2016-03-01 19:14:26Z

4

You could also melt the data and use ggplot2

library(data.table)
library(ggplot2)
#data1 <- as in @John_West's post
dat <- data.table(data1)
melted <- melt(dat,id.vars="Sal",variable.factor=F)

> melted
     Sal variable value
 1: 29.0       T1  4.00
 2: 29.5       T1  7.50
 3: 30.0       T1 10.40
 4: 30.5       T1 12.50
 5: 31.0       T1 14.50
 6: 31.5       T1 16.25
 7: 32.0       T1 18.00
 8: 32.5       T1 19.50
 9: 33.0       T1 20.90
10: 33.5       T1 22.40
11: 34.0       T1 23.60
12: 34.5       T1 24.90
13: 35.0       T1    NA
14: 35.5       T1    NA
15: 29.0       T2    NA
16: 29.5       T2    NA
17: 30.0       T2  1.50
18: 30.5       T2  6.00
19: 31.0       T2  9.00
20: 31.5       T2 11.50
...

ggplot(melted,aes(x=Sal,y=value,group=variable)) + geom_line()

Incidentally this strategy makes it easy to distinguish the data by the kind of observation as well:

ggplot(melted,aes(x=Sal,y=value,color=variable)) + geom_line()

answered Mar 1, 2016 at 19:14

Philip

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1 Comment

Orangeblue Over a year ago

Thanks! Both of your solutions are good, but I can choose one as the answer for this problem.

John_West · Accepted Answer · 2016-03-01 19:07:59Z

3

At first, I suggest you to take plot outside for loop, and leave lines in the loop.

At second, you did not scale the axes properly.

1.dat:

Sal T1 T2 T3 T4 T5 T6
29.0 4.00 NA NA NA NA NA
29.5 7.50 NA NA NA NA NA
30.0 10.40 1.50 NA NA NA NA
30.5 12.50 6.00 NA NA NA NA
31.0 14.50 9.00 NA NA NA NA
31.5 16.25 11.50 4.00 NA NA NA
32.0 18.00 13.50 7.50 NA NA NA
32.5 19.50 15.25 10.00 1.50 NA NA
33.0 20.90 17.00 12.20 5.55 NA NA
33.5 22.40 18.50 14.10 8.50 NA NA
34.0 23.60 20.00 16.05 11.00 4.0 NA
34.5 24.90 21.50 17.50 13.00 7.1 NA
35.0 NA 22.75 19.20 14.70 9.7 1.5
35.5 NA 23.90 20.50 16.50 11.9 5.5

Code:

x11()
data1 <- read.table("1.dat", header=TRUE, sep = " ", check.names=FALSE, as.is=TRUE)
plot(0,0,xlim=c(28,37),ylim=c(0,25),type="n",xlab="X",ylab="Y")

for (i in 2:ncol(data1)){
mydata = na.omit(data.frame(c(data1[1]),c(data1[i])))
lines(mydata)
}
Sys.sleep(10)

edited Mar 1, 2016 at 19:07

answered Mar 1, 2016 at 19:02

John_West

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1 Comment

Orangeblue Over a year ago

Thanks! Both of your solutions are good, but I can choose one as the answer for this problem. I pasted the final code based on ur suggestion.

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