Using ggplot2 to create a plot with more than 2 variables

Question

I am working on a dataset with multiple variables as seen on sample below;(actual data set contains:84 obs. 24 variables). I want to create a single plot which takes in all the variables as opposed to creating a single plot for each variable.

Fruit    Vitamin A(mg) Vitamin C(mg) Calcium(mg)
Pear         61            8             11
Apple        10            2             3
Cherry       35            10            11
Fig          5             2             67

I have tried the code below, an altered version of one suggested in one of the forums;

library(ggplot2)
g<- ggplot(FR, aes(Fruit)
g + geom_point() + facet_grid(. ~ FR[2:26,])

I get error;

Error: unexpected symbol in: "g<- ggplot(FR, aes(Fruit) g"

I am open to any better suggestions for alternatives to represent the dataset.

geom_point() needs both a y and and and x axis. You have only specified an x-axis. Do you want the other columns to be the Y? — Raphael K
– Raphael K, Commented May 4, 2016 at 19:05

rafa.pereira · Accepted Answer · 2016-05-04 20:37:43Z

2

How about this:

To do this, you need to reshape your dataset using gather{tidyr}. Here is a reproducible example on how to do this:

# load libraries
  library(ggplot2)
  library(ggthemes)
  library(tidyr)
  library(googleVis)

# get data for a reproducible example
  data("Fruits")
  colnames(Fruits)[4] <- "Vitamin A(mg)"
  colnames(Fruits)[5] <- "Vitamin C(mg)"
  colnames(Fruits)[6] <- "Calcium(mg)"
  Fruits <- Fruits[ c("Fruit","Vitamin A (mg)" , "Vitamin C (mg)", "Calcium (mg)")]

# reshape the dataset
  df <- gather(data=Fruits, key=Fruit)
  colnames(df)[2] <- "vitamin"


# Plot !
  ggplot(data=df) +
    geom_point(aes(x=vitamin, y=value , color=vitamin)) +
    facet_grid(Fruit~., scale="free_x") +
    theme_minimal()

answered May 4, 2016 at 20:37

rafa.pereira

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1 Comment

user5680053 Over a year ago

This is closest to what I wanted, I made fruits to be my x-values. While the plot looks great on small data set, it's all clustered up and blurry on a data set as large as mine, I might need to categories the variables. Thank you, this was helpful.

Jason · Accepted Answer · 2016-05-04 19:12:27Z

1

I believe you're missing a closing parenthesis. Change:

g<- ggplot(FR, aes(Fruit)

to

g<- ggplot(FR, aes(Fruit))

In my experience, "unexpected symbol" errors usually mean you forgot to close parentheses or braces.

edited May 4, 2016 at 19:12

answered May 4, 2016 at 19:01

Jason

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user5680053 Over a year ago

I got error: Error in layout_base(data, cols, drop = drop) : At least one layer must contain all variables used for facetting

Raphael K · Accepted Answer · 2016-05-04 19:08:33Z

0

You aren't specifying the axes enough.

ggplot(FR, aes(x = Fruit, y = Vitamin A(mg), 
    shape = as.factor(Fruit), 
    color = as.factor(Fruit))) + 
    geom_point() +
    geom_point(aes(x = Fruit, y = Vitamin C(mg))) +
    geom_point(aes(x = Fruit, y = Calcium(mg)))

Is that what you wanted?

answered May 4, 2016 at 19:08

Raphael K

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1 Comment

user5680053 Over a year ago

Works great for variables with the same unit, but not for my case where I have in my data Calories in (kcal). Sorry I forgot to mention this earlier.

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