CODEWITHSUNDEEP
rplot
Chicago1988
Chicago1988

Reputation: 684

x axis not displaying correctly

I have the next function that I want to plot:

eq = function(x)
{ a=(sin(5*x)+cos(7*x))^2 
  b= 5 * (1/sqrt(2*pi*0.05)) * exp(-x^2/(2*0.05))
  1-a-b
}

At first I used:

plot(eq(-10:10), type='l')

but then I changed it to:

plot(eq(-10:10), type='l')
axis (1,at=1:21,labels=(-10:10))

Because the x axis wasn't really showing what I needed.

Problem now is that I see some overlaping numbers (a '10' on top of the '-1', etc) not sure why. enter image description here

My ultimate goal would be to display it like this (with a thick line for both x and y axis): enter image description here

Upvotes: 4

Views: 404

Answers (4)

Calvin
Calvin

Reputation: 1359

If you want axes that are at x=0 and y=0, you can add them manually in the base graphics. Here is some example code. The location of text and tick marks might have to be modified.

enter image description here

eq = function(x)
{ a=(sin(5*x)+cos(7*x))^2 
b= 5 * (1/sqrt(2*pi*0.05)) * exp(-x^2/(2*0.05))
1-a-b
}


# basic plot without axes
plot(y=eq(-10:10)
     ,x=c(-10:10)
     ,xaxt='n'
     ,yaxt='n'
     ,type='l'
     ,col='red'
     ,xlab=''
     ,ylab=''
    )
# grid
grid()

# adding thicker horizontal and vertical lines at axis y=0, x=0
abline(h=0,lwd=2,col='black')
abline(v=0,lwd=2,col='black')

# adding text and ticks for x axis, must be modified based on plot
text(x=-0.7,y=seq(1,-8,-1)[-2],seq(1,-8,-1)[-2])
points(x=seq(-10,10,1)[-11],y=rep(0,20),pch='|')

# adding text and ticks for y axis, must be modified based on plot
text(x=c(seq(-10,10,1))[-11],y=-0.4,c(-10:10)[-11])
points(x=rep(0,9),y=seq(-8,1,1)[-9],pch='―')

# adding text for 0-0 point
text(x=-0.3,-0.2,0)

Upvotes: 3

Stéphane Laurent
Stéphane Laurent

Reputation: 84529

plot(eq(-10:10), type='l') creates a x-axis, so by doing

plot(eq(-10:10), type='l')
axis(1, at=1:21, labels=(-10:10))

you are superimposing two x-axes. Use axes = FALSE:

plot(eq(-10:10), type='l', axes = FALSE)
axis(1, at=1:21, labels=(-10:10))
axis(2)
grid()

enter image description here

I'm using grid() to have the thick lines.

For a better y-axis:

y <- eq(-10:10)
plot(y, type='l', axes = FALSE, ylim = range(pretty(y)))
axis(1, at=1:21, labels=(-10:10))
axis(2)
grid()

enter image description here

Upvotes: 1

LocoGris
LocoGris

Reputation: 4480

To me, dipetkov is a more elegant solution, But if you want to know how to do it the plot way or to know why was not showing your desired result, try this:

eq = function(x)
{ a=(sin(5*x)+cos(7*x))^2 
b= 5 * (1/sqrt(2*pi*0.05)) * exp(-x^2/(2*0.05))
1-a-b
}

plot(eq(-10:10), type='l', xaxt='n', ann=FALSE)
axis (1,at=1:21,labels=(-10:10))

xaxt='n', ann=FALSE will just hide the x axix so you can rewrite your desired one later ( axis (1,at=1:21,labels=(-10:10)))

Upvotes: 3

dipetkov
dipetkov

Reputation: 3690

You need to evaluate the function at a finer grid. It might be easier to use curve.

eq <- function(x) {
  a <- (sin(5 * x) + cos(7 * x))^2
  b <- 5 * (1 / sqrt(2 * pi * 0.05)) * exp(-x^2 / (2 * 0.05))
  1 - a - b
}

curve(eq, from = -10, to = 10, n = 10001)
axis(1, at = -10:10)

Created on 2019-03-07 by the reprex package (v0.2.1)

Upvotes: 3

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