How to change line width in ggplot?

Datalink: the data used

My code:

ccfsisims <- read.csv(file = "F:/Purdue University/RA_Position/PhD_ResearchandDissert/PhD_Draft/GTAP-CGE/GTAP_NewAggDatabase/NewFiles/GTAP_ConsIndex.csv", header=TRUE, sep=",", na.string="NA", dec=".", strip.white=TRUE)
ccfsirsts <- as.data.frame(ccfsisims)
ccfsirsts[6:24] <- sapply(ccfsirsts[6:24],as.numeric)
ccfsirsts <- droplevels(ccfsirsts)
ccfsirsts <- transform(ccfsirsts,sres=factor(sres,levels=unique(sres)))

library(ggplot2)

#------------------------------------------------------------------------------------------
#### Plot of food security index for Morocco and Turkey by sector
#------------------------------------------------------------------------------------------

#_Code_Begin...

datamortur <- melt(ccfsirsts[ccfsirsts$region %in% c("TUR","MAR"), ]) # Selecting regions of interest
datamortur1 <- datamortur[datamortur$variable %in% c("pFSI2"), ] # Selecting the food security index of interest
datamortur2 <- datamortur1[datamortur1$sector %in% c("wht","gro","VegtFrut","osd","OthCrop","VegtOil","XPrFood"), ] # Selecting food sectors of interest
datamortur3 <- subset(datamortur2, tradlib !="BASEDATA") # Eliminating the "BASEDATA" scenario results  

allfsi.f <- datamortur3
fsi.wht <- allfsi.f[allfsi.f$sector %in% c("wht"), ]

Figure29 <- ggplot(data=fsi.wht, aes(x=factor(sres),y=value,colour=factor(tradlib)))
Figure29 + geom_line(aes(group=factor(tradlib),size=2)) + facet_grid(regionsFull~., scales="free_y", labeller=reg_labeller) + scale_colour_brewer(type = "div") +
theme(axis.text.x = element_text(colour = 'black', angle = 90, size = 13, hjust = 0.5, vjust = 0.5),axis.title.x=element_blank()) + 
ylab("FSI (%Change)") + theme(axis.text.y = element_text(colour = 'black', size = 12), axis.title.y = element_text(size = 12, hjust = 0.5, vjust = 0.2)) + 
theme(strip.text.y = element_text(size = 11, hjust = 0.5, vjust = 0.5, face = 'bold'))

My result: Result_Figure

Newresult with aes(size=2): NewResult-Figure

My question: Is there a way to control for line width more precisely to avoid the result in the second plot? I particularly find it document-unfriendly, and more so for publishing purposes to include the plot with the newly defined line width.

best, ismail


Whilst @Didzis has the correct answer, I will expand on a few points

Aesthetics can be set or mapped within a ggplot call.

  • An aesthetic defined within aes(...) is mapped from the data, and a legend created.

  • An aesthetic may also be set to a single value, by defining it outside aes().

As far as I can tell, what you want is to set size to a single value, not map within the call to aes()

When you call aes(size = 2) it creates a variable called `2` and uses that to create the size, mapping it from a constant value as it is within a call to aes (thus it appears in your legend).

Using size = 1 (and without reg_labeller which is perhaps defined somewhere in your script)

Figure29 +
    geom_line(aes(group=factor(tradlib)),size=1) +
    facet_grid(regionsFull~., scales="free_y") +
    scale_colour_brewer(type = "div") +
    theme(axis.text.x = element_text(
          colour = 'black', angle = 90, size = 13,
          hjust = 0.5, vjust = 0.5),axis.title.x=element_blank()) +
    ylab("FSI (%Change)") +
    theme(axis.text.y = element_text(colour = 'black', size = 12), 
          axis.title.y = element_text(size = 12, 
          hjust = 0.5, vjust = 0.2)) + 
    theme(strip.text.y = element_text(size = 11, hjust = 0.5,
          vjust =    0.5, face = 'bold'))

enter image description here

and with size = 2

 Figure29 + 
     geom_line(aes(group=factor(tradlib)),size=2) +
     facet_grid(regionsFull~., scales="free_y") + 
     scale_colour_brewer(type = "div") +
     theme(axis.text.x = element_text(colour = 'black', angle = 90,
          size = 13, hjust = 0.5, vjust = 
          0.5),axis.title.x=element_blank()) + 
     ylab("FSI (%Change)") +
     theme(axis.text.y = element_text(colour = 'black', size = 12),
          axis.title.y = element_text(size = 12,
          hjust = 0.5, vjust = 0.2)) + 
      theme(strip.text.y = element_text(size = 11, hjust = 0.5,
          vjust = 0.5, face = 'bold'))

enter image description here

You can now define the size to work appropriately with the final image size and device type.


Line width in ggplot2 can be changed with argument size= in geom_line().

#sample data
df<-data.frame(x=rnorm(100),y=rnorm(100))
ggplot(df,aes(x=x,y=y))+geom_line(size=2)

enter image description here


Line width in ggplot2 can be changed with argument lwd= in geom_line().

geom_line(aes(x=..., y=..., color=...), lwd=1.5)

It also looks like if you just put the size argument in the geom_line() portion but without the aes() it will scale appropriately. At least it works this way with geom_density and I had the same problem.


If you want to modify the line width flexibly you can use "scale_size_manual," this is the same procedure for picking the color, fill, alpha, etc.

library(ggplot2)
library(tidyr)

x = seq(0,10,0.05)

df <- data.frame(A = 2 * x + 10,
                 B = x**2 - x*6,
                 C = 30 - x**1.5,
                 X = x)


df = gather(df,A,B,C,key="Model",value="Y")


ggplot( df, aes (x=X, y=Y, size=Model, colour=Model ))+
  geom_line()+
  scale_size_manual( values = c(4,2,1) ) +
  scale_color_manual( values = c("orange","red","navy") )