Hi, I'm wondering if it is possible to "add" the values of two hashes together. Suppose I had: hash1 = {:key_one=>100, :key_two=>200} hash2 = {:key_two=>300, :key_three=>400} I'd like to "add" the hashes together so that I get result => {:key_one=>100, :key_two=>500, :key_three=>400} Do I need to write my own function to parse through each hash's keys? Is there a built-in way to do this? Thanks!

on 2009-01-28 20:09

on 2009-01-28 20:23

On Wed, Jan 28, 2009 at 11:07 AM, Bryson Smith <bryson@mailinator.com> wrote: > Do I need to write my own function to parse through each hash's keys? > Is there a built-in way to do this? You can try Hash#merge: irb(main):007:0> a = {:a => 1} => {:a=>1} irb(main):008:0> b = {:b => 2} => {:b=>2} irb(main):009:0> c = a.merge( b ) => {:a=>1, :b=>2} Note that if you have duplicate keys, the values in b will override the values in a. Ben

on 2009-01-28 20:31

On Jan 28, 2009, at 2:07 PM, Bryson Smith wrote: > result => {:key_one=>100, :key_two=>500, :key_three=>400} > > Do I need to write my own function to parse through each hash's keys? > Is there a built-in way to do this? > > Thanks! irb> hash1 = {:key_one=>100, :key_two=>200} => {:key_two=>200, :key_one=>100} irb> hash2 = {:key_two=>300, :key_three=>400} => {:key_two=>300, :key_three=>400} irb> result = hash1.merge(hash2) {|key,val1,val2| val1+val2} => {:key_two=>500, :key_three=>400, :key_one=>100} You only have to write the block that deals with the duplicates for 'key' -Rob Rob Biedenharn http://agileconsultingllc.com Rob@AgileConsultingLLC.com

on 2009-01-28 20:33

Bryson Smith wrote: > Hi, > > I'm wondering if it is possible to "add" the values of two hashes > together. Suppose I had: > > hash1 = {:key_one=>100, :key_two=>200} > hash2 = {:key_two=>300, :key_three=>400} > > I'd like to "add" the hashes together so that I get > > result => {:key_one=>100, :key_two=>500, :key_three=>400} > > Do I need to write my own function to parse through each hash's keys? > Is there a built-in way to do this? > > Thanks! No built-in way, but it would be easy to use hash1.each_key to iterate over the keys of hash1. For every key in hash1, get its value for that key from hash1 and hash2, add the two values and store the sum as the value of that key in result. The question is, what happens if there's a key in hash1 that isn't in hash2, or vice versa?

on 2009-01-28 21:13

On Jan 28, 2009, at 2:31 PM, Tim Hunter wrote: >> > value of that key in result. > > The question is, what happens if there's a key in hash1 that isn't in > hash2, or vice versa? In case it was missed the first time: irb> result = hash1.merge(hash2) {|key,val1,val2| val1+val2} => {:key_two=>500, :key_three=>400, :key_one=>100} You only have to write the block that deals with the duplicates for 'key' -Rob Rob Biedenharn http://agileconsultingllc.com Rob@AgileConsultingLLC.com