The next colour

Question

Challenge

Consider the rainbow as seven colours, represented by strings as Red Orange Yellow Green Blue Indigo Violet.
Your task is to create a program that receives one of these colours as input and outputs next in order rainbow colour. This includes overlapping Violet -> Red

Input

A string containing one of rainbow colours.

Output

The next in order colour of the rainbow.

Rules

• Colour names are case sensitive. They must match the case included in this post.
• The input will always be valid. Any behavior is allowed for invalid input.
• This is code golf, so the shortest amount of bytes wins!

Example Input and Output

Input -> Output
Red -> Orange
Orange -> Yellow
Yellow -> Green
Green -> Blue
Blue -> Indigo
Indigo -> Violet
Violet -> Red

Answer 1

Bash + GNU Utilities, 63

grep -Po $1\\K.[a-z]+<<<RedOrangeYellowGreenBlueIndigoVioletRed

The list of colours is reversed so that a regex lookahead may be used. The lookahead boilerplate is one byte shorter than the lookbehind boilerplate. Of course we can do better the PCRE \K.

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Answer 2

Factor, 81 bytes

[ qw{ Red Orange Yellow Green Blue Indigo Violet } [ index 1 + 7 mod ] keep nth ]

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Answer 3

Red, 74 bytes

func[c][prin select[Red Orange Yellow Green Blue Indigo Violet Red]load c]

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Answer 4

APL+WIN, 66 bytes

↑(c⍳⊂⎕)⌽c←'Red' 'Orange' 'Yellow' 'Green' 'Blue' 'Indigo' 'Violet'

Prompts for screen input of colour as a string.

Answer 5

C (gcc) preprocessor macro, 74

Score is 74 bytes passed to the compiler.

Same idea as @nwellnhof's Perl answer.

-Df(c)=printf("%.6s","IndigoBlue  VioletYellowOrangeRed   Green"+*c/4%8*6)

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Answer 6

Python 2, 89 87 bytes

def f(c):a="red orange yellow green blue indigo violet".split();print a[-~a.index(c)%7]

Test cases:

f("red") -> orange

f("orange") -> yellow

f("yellow") -> green

f("green") -> blue

f("blue") -> indigo

f("indigo") -> violet

f("violet") -> red

f("notAColour") -> Error

Answer 7

C (gcc), 88 bytes

f(char*s){printf("%.6s",(strstr("red   violetindigoblue  green yelloworangered",s)+6));}

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Answer 8

Python 3, 85 bytes

c='Red Orange Yellow Green Blue Indigo Violet'.split()
f=lambda x:c[(c.index(x)+1)%7]

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Answer 9

Wolfram Language (Mathematica), 84 bytes

TextWords version (84 Bytes but slow)

#/.Thread[#->RotateLeft@#&[TextWords@"Red Orange Yellow Green Blue Indigo Violet"]]&

StringSplit (86 Bytes)

#/.Thread[#->RotateLeft@#&[StringSplit@"Red Orange Yellow Green Blue Indigo Violet"]]&

Built-in color names called by number, also 86 Bytes:

#/.Thread[#->RotateLeft@#&[ColorData["HTML","Range"][[1,{114,100,139,52,10,57,135}]]]]

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Answer 10

Lua, 89 bytes

c="Red   OrangeYellowGreen Blue  IndigoVioletRed"r=c:find(io.read())+6print(c:sub(r,r+5))

Outputs some trailing spaces. Example:

input: Yellow
output: Green 
space here:  ^

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Lua, 102 bytes

c="Red   OrangeYellowGreen Blue  IndigoVioletRed"r=c:find(io.read())+6print(c:sub(r,r+5):match("%a+"))

Doesn't output any trailing spaces.

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Answer 11

Tcl, 98 bytes

puts [lindex [set L {Red Orange Yellow Green Blue Indigo Violet}] [expr ([lsearch $L $argv]+1)%7]]

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---

Tcl, 98 bytes

puts [lindex [set L {Red Orange Yellow Green Blue Indigo Violet Red}] [expr [lsearch $L $argv]+1]]

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Answer 12

Swift, 121 113 bytes

let s=readLine()!;let i=["Red","Orange","Yellow","Green","Blue","Indigo","Violet"];print(i[(i.index(of:s)!+1)%7])

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