How to plot the min and max of each row in y-axis?

Question

I'm new and learning R and got a problem plotting the min and max value of a matrix. The matrix is something like this:

X Y1 Y2 Y3 Y4 Y5

1 0.5 0.6 0.3 0.3 0.2

2 0.3 0.4 0.1 0.7 0.4

3 0.4 0.3 0.5 0.6 0.3

Now I would like to plot the first column(X) as x-axis, and pick out the min and max values of each row (e.g. X=1, Ymin=0.2, Ymax=0.6 in the first row), and plot them as the y-axis.

Could someone help me to figure it out?

Answer 1

Here is one possibility, considering you want a scatterplot.

#reading your data
table =  read.table(header=TRUE, text="
             X Y1 Y2 Y3 Y4 Y5
             1 0.5 0.6 0.3 0.3 0.2
             2 0.3 0.4 0.1 0.7 0.4
             3 0.4 0.3 0.5 0.6 0.3", sep= " ")

#using a for loop to filter only data to be used in the plot (X, Min_Y, Max_Y)
df = data.frame(X=NA,min_Y=NA,max_Y=NA)

for (i in c(1:length(df))) {

X = table[i,1] #X values from table
min_Y = c(min(table[i,c(2:6)])) #minimum values inside table columns 2 to 6
max_Y = c(max(table[i,c(2:6)])) #maximum values inside table columns 2 to 6

df = rbind(df,c(X,min_Y,max_Y)) #new df with X, Min_Y, Max_Y

}

df = df[-1,]
df #df results

  X min_Y max_Y
2 1   0.2   0.6
3 2   0.1   0.7
4 3   0.3   0.6

#produce scatterplot with R package ggplot2
library(ggplot2)

ggplot(df) + 
  geom_point(aes(x=X,y=min_Y),colour="red") + 
  geom_point(aes(x=X,y=max_Y),colour="blue") +
  ylab("Y") +
  theme_bw()

Answer 2

A solution with rbind and 2 apply functions (for min and max) (surely not the best tho) :

mat <- as.matrix(read.table(header = T, text = "X Y1 Y2 Y3 Y4 Y5

1 0.5 0.6 0.3 0.3 0.2

2 0.3 0.4 0.1 0.7 0.4

3 0.4 0.3 0.5 0.6 0.3"))

mat2 <- t(rbind(X = mat[ ,1], Ymin = apply(mat[ ,-1], 1, min), Ymax = apply(mat[ ,-1], 1, max)))

matplot(mat2[ ,1], mat2[ ,-1], pch = 20, cex = 1.5)

Answer 3

For example using pmin and pmax:

mn = Reduce(pmin,as.list(dat[,-1]))
mx = Reduce(pmax,as.list(dat[,-1]))
library(lattice)
xyplot(mn+mx~x,data.frame(x= dat[,1],mn=mn,mx=mx),
   type='l',auto.key=T,
   ylab=list(label="max and min"))

Where dat is :

dat <- 
  read.table(text='
X Y1 Y2 Y3 Y4 Y5
1 0.5 0.6 0.3 0.3 0.2
2 0.3 0.4 0.1 0.7 0.4
3 0.4 0.3 0.5 0.6 0.3',header=TRUE)

Answer 4

So here is (another...) way to get the column-wise min and max (using m as your matrix).

z <- t(apply(m,1,
             function(x)return(c(x[1],min=min(x[2:length(x)]),max=max(x[2:length(x)])))))
z <- data.frame(z)
z
#      X min max
# [1,] 1 0.2 0.6
# [2,] 2 0.1 0.7
# [3,] 3 0.3 0.6

From here, plotting is straightforward.

plot(z$X, z$max, ylim=c(min(z$min),max(z$max)),col="blue")
points(z$X, z$min, col="red")