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ggplot2 geom_curve() in R: Draw Curved Connections

The geom_curve() function in ggplot2 draws CURVED arcs between two points, useful for connecting nodes in network plots, decorative annotations, or stylistic alternatives to straight segments.

By Selva Prabhakaran  ·  Published May 12, 2026  ·  Last updated May 12, 2026
⚡ Quick Answer
ggplot(df, aes(x, y, xend = xend, yend = yend)) + geom_curve()
geom_curve(curvature = 0.5)              # curvier
geom_curve(curvature = -0.5)             # bend other direction
geom_curve(angle = 45)                    # control arc orientation
geom_segment()                            # straight version

Need explanation? Read on for examples and pitfalls.

📊 Is geom_curve() the right tool?
STARTcurved connection between 2 pointsgeom_curve()straight linegeom_segment()arrow on a curvegeom_curve(arrow = arrow())network edges with bendsgeom_curve()subtle annotation arcgeom_curve(curvature = 0.2)

What geom_curve() does in one sentence

geom_curve() draws curved (arc) line segments from (x, y) to (xend, yend) for each row of data. Same arguments as geom_segment plus curvature and angle.

Syntax

geom_curve(mapping = NULL, data = NULL, curvature = 0.5, angle = 90, ncp = 5, arrow = NULL, ...). Requires aes(x, y, xend, yend).

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RCurved connection
library(ggplot2) df <- tibble(x = 0, y = 0, xend = 5, yend = 5) ggplot(df, aes(x, y, xend = xend, yend = yend)) + geom_curve(curvature = 0.3) + geom_point() + geom_point(aes(x = xend, y = yend))

  

  





Tip
Curvature 0 is straight (= geom_segment); positive curves clockwise; negative curves counterclockwise. Range typically 0 to 1.



Five common patterns



1. Standard curve




  

    
RDefault curvature 0.5

    
ggplot(df, aes(0, 0, xend = 5, yend = 5)) +
  geom_curve()

    

      
      
    

    

  

  





2. Reverse direction




  

    
RCurve the other way

    
ggplot(df, aes(0, 0, xend = 5, yend = 5)) +
  geom_curve(curvature = -0.5)

    

      
      
    

    

  

  





3. Tight curve




  

    
RMore dramatic arc

    
geom_curve(curvature = 0.8)

    

      
      
    

    

  

  





4. Curve with arrow




  

    
RAnnotation

    
ggplot(mtcars, aes(wt, mpg)) +
  geom_point() +
  geom_curve(aes(x = 4, y = 30, xend = 5, yend = 25),
             arrow = arrow(length = unit(0.3, "cm")),
             color = "red")

    

      
      
    

    

  

  





5. Network edges




  

    
RCurved edges between nodes

    
edges <- tibble(x1 = c(0, 1), y1 = c(0, 1), x2 = c(1, 2), y2 = c(1, 0))
ggplot(edges, aes(x1, y1, xend = x2, yend = y2)) +
  geom_curve(curvature = 0.3)

    

      
      
    

    

  

  





Key Insight
curvature controls bend AMOUNT; angle controls bend DIRECTION. Most users only need curvature; angle is for fine-tuning.



geom_curve() vs geom_segment() vs geom_line()







Function
Shape
Endpoints






geom_curve()
Curved arc
(x, y) to (xend, yend) per row




geom_segment()
Straight
(x, y) to (xend, yend) per row




geom_line()
Polyline
Across rows in sorted x







A practical workflow



Use geom_curve for stylistic annotations or network edge plots.




  

    
RInteractive R

    
ggplot(mtcars, aes(wt, mpg)) +
  geom_point() +
  geom_curve(
    aes(x = 4.5, y = 30, xend = 5.4, yend = 17.3),
    arrow = arrow(length = unit(0.3, "cm")),
    color = "red"
  ) +
  annotate("text", x = 4, y = 31, label = "Heaviest car")

    

      
      
    

    

  

  





Common pitfalls



Pitfall 1: too much curvature. Above 1 produces extreme bends. Stay 0 to 1 for natural-looking arcs.



Pitfall 2: missing aesthetics. Like geom_segment, requires x, y, xend, yend.



Warning
geom_curve() doesn't connect across rows. Each row is one curve. For curved trajectories across many points, use geom_path with smoothing.



Try it yourself





Try it: Draw a curved arrow from (0,0) to (5,5). Save to ex_plot.



  

    
RYour turn: curved arrow

    
ex_plot <- ggplot(tibble(x = 0, y = 0, xend = 5, yend = 5),
                  aes(x, y, xend = xend, yend = yend)) +
  # your code here

    

      
      
    

    

  

  





Click to reveal solution



  

    
RSolution

    
ex_plot <- ggplot(tibble(x = 0, y = 0, xend = 5, yend = 5),
                  aes(x, y, xend = xend, yend = yend)) +
  geom_curve(arrow = arrow(length = unit(0.3, "cm")), curvature = 0.3)

    

      
      
    

    

  

  





Explanation: Curve with curvature 0.3 and arrow at the end.










After mastering geom_curve, look at:



    


  • geom_segment(): straight version
    • 


  • arrow(): arrowhead spec
    • 


  • geom_path() / geom_line(): multi-point lines
    • 


  • annotate(): one-off annotations
    • 





FAQ



What does geom_curve do in ggplot2?



geom_curve() draws curved arc segments between (x, y) and (xend, yend). Same as geom_segment but curved.



How do I control the curve direction?



Use the curvature argument: positive curves clockwise; negative counterclockwise; 0 is straight.



What is the difference between geom_curve and geom_segment?



geom_segment is straight; geom_curve is curved. Otherwise identical aesthetics and arguments.



Can I add an arrow to geom_curve?



Yes. Pass arrow = arrow(). Same as geom_segment.



Does curvature have to be between 0 and 1?



No, but values outside this range produce extreme curves. Practical range is 0 to 1.



          

        


        
      


      

        

        
© 2016-2026 Selva Prabhakaran.
          This work is licensed under the Creative Commons License.
        

        

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