How do I figure out the percentage of elements in my array whose value is between 1 and 100?

Question

I'm using Ruby 2.4. I have a data array that has a bunch of strings ...

["a", "1", "123", "a2c", ...]

I can check the percentage of elements in my array that are exclusively numbers using

data_col.grep(/^\d+$/).size / data_col.size.to_f

but how do I check the percentage of elements taht are numbers and whose value falls between 1 and 100?

There's always a regex: http://stackoverflow.com/q/13473523/477037 ;-) — Stefan, Feb 02 '17 at 17:16

Ursus · Accepted Answer · 2017-02-02T17:13:16.820

2

Try something like

data_col.grep(/^\d+$/).count { |item| item.to_i.between?(1, 100) } / data_col.size.to_f

edited Feb 02 '17 at 17:13

answered Feb 02 '17 at 15:57

Ursus

Hi, When my data_col is ["99a", "a", "", "25"], running the above returns 0. Shoudn't it return ".25" since one of the elements in my array is a number? – Feb 02 '17 at 16:11
Oh I'm sorry, I forgot to copy the ".to_f" at the end of your statement. – Feb 02 '17 at 16:23
`item.to_i.between?(1, 100)` is even more descriptive. – Stefan Feb 02 '17 at 17:12
Done. Thank you Stefan :) – Ursus Feb 02 '17 at 17:13
The `grep(/^\d+$/)` part is actually unnecessary, because `to_i` always returns an integer. – Stefan Feb 03 '17 at 08:32

score 1 · Answer 2 · answered Feb 02 '17 at 18:08

1

Try this

1.0 * array.map(&:to_i).grep(1..100).size / array.size

How does this work?

answered Feb 02 '17 at 18:08

akuhn

You can avoid `1.0 *` by using `fdiv` instead of `/`. – Stefan Feb 03 '17 at 08:32

2 Answers2