How do I update a Hash value's array?

Question

I'm using Ruby and have a hash, call it foo, and its value is an Array with a fixed length of 2.

How can I update one of the indexes within the hash values array? Here's an example:

foo.each do |k, v|
  if k == 'some value'
    foo[k] = update v[0]
    foo[k] = update v[1]
  end
end

Further clarification:

I'm looping through a file and inside I want to to see if the current line matches the hash key k. If it does I want to update the timestamp in the values array, which is stored in v[1].

# read lines  from the input file
File.open(@regfile, 'r') do |file|
  file.each_line do |line|
    # cache control
    cached = false

    # loop through @cache
    @cache.each do |k, v|
      # if (url is cached)
      if line == k
        # update the timestamp
        @cache[k] = Time.now.getutc  # need this to be put in v[1]

        # set cached to true
        cached = true
      end
    end

    # if cached go to next line
    next if cached

    # otherwise add to cache
    updateCache(line)
  end
end

why not just set foo[k][0] = new_value; foo[k][1] = new_value2 — klochner
– klochner, Commented Dec 8, 2011 at 21:13
Show some sample of input/expected output, so we can understand better your question. — Guilherme Bernal
– Guilherme Bernal, Commented Dec 8, 2011 at 21:14
@klochner i was going to try that, but i wasn't sure if typing foo[k][1] would update the second position in v's array. — CoryDorning
– CoryDorning, Commented Dec 8, 2011 at 21:23

Guilherme Bernal · Accepted Answer · 2011-12-09 12:37:00Z

3

# cache control
cached = false

# loop through @cache
@cache.each do |k, v|
  # if (url is cached)
  if line == k
    # update the timestamp
    @cache[k] = Time.now.getutc  # need this to be put in v[1]

    # set cached to true
    cached = true
  end
end

# if cached go to next line
next if cached

# otherwise add to cache
updateCache(line)

A better and faster solution:

if @cache.include? line
  @cache[line][1] = Time.now.utc
else
  updateCache(line)
end

edited Dec 9, 2011 at 12:37

answered Dec 8, 2011 at 22:07

Guilherme Bernal

8,32329 silver badges44 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Victor Moroz Over a year ago

cached = true => else updateCache(line) end and cached is not required

Marek Příhoda · Accepted Answer · 2011-12-08 21:18:27Z

2

foo = { 'v1' => [1, 2], 'v2' => [3, 4] }

foo.each do |k, v|
  v[0] += 10
  v[1] += 10
end

p foo  # {"v1"=>[11, 12], "v2"=>[13, 14]}

answered Dec 8, 2011 at 21:18

Marek Příhoda

11.2k3 gold badges44 silver badges53 bronze badges

1 Comment

CoryDorning Over a year ago

i think this is what i want. trying now.

Collectives™ on Stack Overflow

How do I update a Hash value's array?

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related