ratio-calculator.rb

Need to find the missing value in a ratio? This script will help you do that quickly.

Note: for convenience, I've made this into a Ratio Calculator Alfred workflow.

Usage

Give numeric arguments in a series of three numbers with a ?, x, or any non-number to indicate the missing value.

Example

Solve for x: 2/4 = x/10

~ ruby ratio-calculator.rb 2 4 ? 10
5

Two decimal places are included in default usage. Trailing zeroes and decimal points in the case of integers like the 5 above will be trimmed. See the -r flag below to change the number of included decimal places.

Flags

-r [number], --round [number]

Round the result to [number] decimal places. Default: 2

~ ruby ratio-calculator.rb 12 345 ? 678
23.58

~ ruby ratio-calculator.rb 12 345 ? 678 -r 6
23.582609

-d, --empty_decimals

By default, integers are returned without a decimal point and two trailing zeroes, even though values are calculated as floating point numbers and rounded to two decimal places.

Use this flag if you want two empty decimal places to be returned.

~ ruby ratio-calculator.rb 2 4 ? 10 -d
5.00

-v, --verbose

Instead of just returning the missing number, return the entire ratio as a string with the missing number plugged in.

~ ruby ratio-calculator.rb -v 2 4 ? 10
2/4 [5]/10

-w, --without_newline

Returns result without a newline at the end. Useful for piping into other programs.

For example, copying the result to the clipboard on OS X:

~ ruby ratio-calculator.rb 2 4 ? 10 -w | pbcopy

Copy to Clipboard

Use the --without_newline flag to remove the newline that would otherwise be printed to the terminal, then pipe the result to pbcopy to copy the result to your clipboard, ready for pasting. (This only works on OS X.)

~ ruby ratio-calculator.rb --without_newline 2 4 ? 10 | pbcopy

If you want to see the result as well as copy to the clipboard (source):

~ ruby ratio-calculator.rb --without_newline 2 4 ? 10 | pbcopy | tee /dev/tty
5

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See Also

I've written a Ratio Calculator Alfred workflow that uses this script. It is the most convenient application for me.

The current implementation of this script is written in Ruby, but there is an identical working Python version as well.

Thanks

• Justin Falcone and Cody Robbins for code review