Color scales and palettes in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a basic color palette with three colors.

R Programming

palette <- c("red", [1], "blue")
print(palette)

Drag options to blanks, or click blank then click option'

A"orange"

B"green"

C"purple"

D"yellow"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a color name without quotes

Forgetting commas between colors

The code creates a vector of colors. "green" is the correct middle color to complete the palette.

2fill in blank

medium

Complete the code to generate a color gradient from blue to red with 5 colors using colorRampPalette.

R Programming

colors <- colorRampPalette(c("blue", [1]))(5)
print(colors)

Drag options to blanks, or click blank then click option'

A"purple"

B"yellow"

C"green"

D"red"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a color not matching the gradient end

Missing quotes around color names

The function colorRampPalette creates a gradient between the colors given. "red" is needed to create a gradient from blue to red.

3fill in blank

hard

Fix the error in the code to correctly display a palette of 4 colors using brewer.pal from RColorBrewer.

R Programming

library(RColorBrewer)
palette <- brewer.pal([1], "Set1")
print(palette)

Drag options to blanks, or click blank then click option'

A4

B3

C5

D8

Attempts:

3 left

💡 Hint

Common Mistakes

Using a number less than 3

Using a number greater than the palette max

brewer.pal requires the number of colors to be between 3 and the maximum allowed for the palette. "Set1" supports up to 9 colors, so 4 is correct.

4fill in blank

hard

Fill both blanks to create a named vector of colors for categories using a manual palette.

R Programming

categories <- c("A", "B", "C")
colors <- c([1] = "red", [2] = "blue", "green")
names(colors) <- categories
print(colors)

Drag options to blanks, or click blank then click option'

A"cat1"

B"catA"

C"catB"

D"catC"

Attempts:

3 left

💡 Hint

Common Mistakes

Using names that are not strings

Repeating the same name twice

The named vector assigns names to colors. "catA" and "catB" are used as names for the first two colors.

5fill in blank

hard

Fill all three blanks to create a color scale using ggplot2 with a manual palette for factor levels.

R Programming

library(ggplot2)
data <- data.frame(x = 1:3, y = c(3, 2, 5), group = factor(c("low", "medium", "high")))
ggplot(data, aes(x, y, color = group)) +
  geom_point(size = 5) +
  scale_color_manual(values = c([1] = "blue", [2] = "orange", [3] = "green"))

Drag options to blanks, or click blank then click option'

A"low"

B"medium"

C"high"

D"group"

Attempts:

3 left

💡 Hint

Common Mistakes

Using variable names instead of factor levels

Missing quotes around names

The scale_color_manual function maps factor levels to colors. The factor levels "low", "medium", and "high" must be named in the values vector.