Array Comparison

Ruby
1

Hi Guys

I have compared an array and ‘0’ is being returned which indicates to
me that that array is equal

p t = $ie.table(:index, ‘2’).to_a.flatten
p t <=> [“HINCKLEY”, “HINDHEAD”, “HINTON ST GEORGE”]

Now would it be possible for me to extract any differences from this
array (that is, when the array is not equal)?

Or should I really be using Test::Unit: to assert array equality?

aidy

2

On 17.08.2006 13:32, aidy wrote:

Or should I really be using Test::Unit: to assert array equality?

You can use Array#zip (block form) to determine any differences.

[“HINCKLEY”, “HINDHEAD”, “HINTON ST GEORGE”].zip(t) do |a,b|
if a != b
print "Difference: ", a.inspect, " ", b.inspect, “\n”
end
end

Kind regards

robert
3

Robert K. schrieb:

You can use Array#zip (block form) to determine any differences.

[“HINCKLEY”, “HINDHEAD”, “HINTON ST GEORGE”].zip(t) do |a,b|
if a != b
print "Difference: ", a.inspect, " ", b.inspect, “\n”
end
end

But note that this doesn’t work if the second array contains more
elements than the first:

[1].zip [1, 2, 3] # => [[1, 1]]

It is also problematic if the arrays can contain nil:

[nil, nil, nil].zip [nil] # => [[nil, nil], [nil, nil], [nil, nil]]

Regards,
Pit

4

You could always add an XOR function to the Array class.

class Array
def XOR(i)
return (i | self) - (i & self)
end

def ^(i)
return XOR(i)
end
end

It should be there already anyway, even if it is just syntactic sugar…

5

Now would it be possible for me to extract any differences from this
array (that is, when the array is not equal)?

Or should I really be using Test::Unit: to assert array equality?

aidy

t = [2, 3, 4, 5]

use == if you want to test for equality

p t == [2, 3, 4, 5] # => true

if t != [3, 4, 5, 6]

you may use the array set methods to show the differences

p t - [3, 4, 5, 6] #=> [2]
p [3, 4, 5, 6] - t #=> [6]
p ([3, 4, 5, 6] | t) - ([3, 4, 5, 6] & t) #=> [6, 2]
end

cheers

Simon