Plot lines in ggplot from a list of dataframes

Question

I have a list of data.frames:

samplelist = list(a = data.frame(x = c(1:10), y=rnorm(10),
                 b= data.frame(x=c(5:10), y = rnorm(5),
                 c = data.frame(x=c(2:12), y=rnorm(10))

I'd like to structure a ggplot of the following format:

ggplot()+ 
    geom_line(data=samplelist[[1]], aes(x,y))+
    geom_line(data=samplelist[[2]], aes(x,y))+
    geom_line(data=samplelist[[3]], aes(x,y))

But that isn't super automated. Does anyone have a suggestion for how to address this?

Thanks!

FYI, your samplelist code has a few errrors.

eipi10
– eipi10

2017-02-14 15:59:27 +00:00
Commented Feb 14, 2017 at 15:59 — eipi10
– eipi10, Commented Feb 14, 2017 at 15:59

eipi10 · Accepted Answer · 2017-02-14 20:30:59Z

12

ggplot works most efficiently with data in "long" format. In this case, that means stacking your three data frames into a single data frame with an extra column added to identify the source data frame. In that format, you need only one call to geom_line, while the new column identifying the source data frame can be used as a colour aesthetic, resulting in a different line for each source data frame. The dplyr function bind_rows allows you to stack the data frames on the fly, within the call to ggplot.

library(dplyr)
library(ggplot2)

samplelist = list(a = data.frame(x=c(1:10), y=rnorm(10)),
                  b = data.frame(x=c(5:10), y=rnorm(6)),
                  c = data.frame(x=c(2:12), y=rnorm(11)))

ggplot(bind_rows(samplelist, .id="df"), aes(x, y, colour=df)) +
  geom_line()

I assumed above that you would want each line to be a different color and for there to be a legend showing the color mapping. However, if, for some reason, you just want three black lines and no legend, just change colour=df to group=df.

edited Feb 14, 2017 at 20:30

answered Feb 14, 2017 at 15:58

eipi10

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1 Comment

Cos Over a year ago

I'm receiving Error in bind_rows_(x, .id) : Argument 1 can't be a list containing data frames

LuckySeedling · Accepted Answer · 2017-02-14 15:38:12Z

3

Or you could use lapply.

library(ggplot2)

samplelist = list(a = data.frame(x = c(1:10), y=rnorm(10)),
                  b= data.frame(x=c(5:10), y = rnorm(6)),
                  c = data.frame(x=c(2:12), y=rnorm(11)))

p <- ggplot()

plot <- function(df){
    p <<- p + geom_line(data=df, aes(x,y))
}

lapply(samplelist, plot)

p

answered Feb 14, 2017 at 15:38

LuckySeedling

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1 Comment

baptiste Over a year ago

using <<- is often not the best strategy in R (typically because one prefers to avoid side-effects in non-local environments); I think Reduce() is more idiomatic here.

MeetMrMet · Accepted Answer · 2017-02-15 15:34:17Z

3

This will work -

library(ggplot2)
samplelist <- list(a = data.frame(x = c(1:10), y=rnorm(10)),
                  b = data.frame(x=c(5:10), y = rnorm(6)),
                  c = data.frame(x=c(2:12), y=rnorm(11)))

p <- ggplot()
for (i in 1:3) p <- p + geom_line(data=samplelist[[i]], aes(x,y))
p

edited Feb 15, 2017 at 15:34

answered Feb 14, 2017 at 15:30

MeetMrMet

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2 Comments

baptiste Over a year ago

your suggestion of using i in aes() will fail

MeetMrMet Over a year ago

Good point, they would all need to be in the same df to use that. edited accordingly

baptiste · Accepted Answer · 2017-02-14 18:40:38Z

1

Reduce is another option to add things iteratively,

library(ggplot2)

samplelist = list(a = data.frame(x = c(1:10), y=rnorm(10)),
                  b= data.frame(x=c(5:10), y = rnorm(6)),
                  c = data.frame(x=c(2:12), y=rnorm(11)))

pl <- Reduce(f = function(p, d) p + geom_line(data=d, aes(x,y)), 
             x = samplelist, init = ggplot(), accumulate = TRUE)

gridExtra::grid.arrange(grobs = pl)

answered Feb 14, 2017 at 18:40

baptiste

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