CODEWITHSUNDEEP
rggplot2
iae
iae

Reputation: 3

Problems with ggplot2: draw a vertical line between x axis (from y=0) to the maximum point at each x value

I'm trying to graph the number of times a price appears in my database group by chain, represent the chain with different colours and draw a line that connect the x axis (y=0) to the maximum point at each price (x value) with the chain colour. If two different chains have the same price I want the lines to overlap. This is my data: Data

For example: price 39.5 appears two times for chain b, and one for chain a.

I want a graph with points and lines. Each point must be the number of times a price appears in each chain coloured according to chain. Up to this point I can graph it, I get this graph:

Graph1

The problem arises when I try to connect points with x axis, I try geom_segment but it gives me a weird graph with diagonal lines when the same price appears in more than one chain, like this:

Graph2

This is my code:

gP1 <- ggplot(fP1, aes(Price, N, color=Chain), group=Price) +
    geom_point() +
    geom_segment(aes(xend=N, color=Chain, group=Price), yend=0)

Any help would be appreciated, I want to get a graph like this one:

Graph3

Thanks in advance!

Upvotes: 0

Views: 1605

Answers (1)

Duck
Duck

Reputation: 39603

Try this approach with geom_segment() defining the proper values for x and y positions. Here the code:

library(ggplot2)
#Data
fP1 <- data.frame(Price=c(39.5,39.5,39.9,39.9,40,42.5,42.8,45,46,47.9,50),
                 Chain=c('a','b','h','c','d','e','f','f','e','f','g'),
                 N=c(1,2,1,4,1,1,1,1,2,1,3))
#Plot
ggplot(fP1, aes(Price, N, color=Chain, group=Price)) +
  geom_point() +
  geom_segment( aes(x=Price, xend=Price, y=0, yend=N))+
  theme_bw()

Output:

enter image description here

The previous sketch considers all the setting for geom_segment(). It can by simplified to this (Many thanks and all credit to @RuiBarradas):

#Plot 2
ggplot(fP1, aes(Price, N, color=Chain, group=Price)) +
  geom_point() +
  geom_segment( aes(xend=Price,yend=0))+
  theme_bw()

It will produce same output.

Upvotes: 4

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