From: shawn bright <nephish@...>
Date: 2006-12-22T06:59:22+09:00
Subject: Re: prob with each_with_index

------=_Part_60381_28670901.1166738359564
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

On 12/21/06, Chunyun Zhao <chunyun.zhao@gmail.com> wrote:
>
> hit passed in the block is the elment, not the array.
>
> Try this:
>
> @flow_sensor.flow_hits.each_with_index do |hit, i|
>          if i > 4 # start with 3rd hit in db
>              time_diff = hit.date_time.to_i -
> @flow_sensor.flow_hits[i-3].date_time.to_i
>              value_diff = hit.value - @flow_sensor.flow_hits[i-3].value
>              min = time_diff / 60
>              val = value_diff / min
>              plots.push(val)
>              times.push(hit.date_time)
>          end
>        end
>
>
> On 12/21/06, shawn bright <nephish@gmail.com> wrote:
> >
> > lo there all,
> >
> > i am having a problem making each_with_index do what i need it to do.
> > the issue is...
> >
> > i need to evaluate the gpm of a flow sensor.
> > we are skipping over three database entries to get the values.
> > difference in value / difference in time = gpm. ok, easy enough.
> >
> > but this code
> >
> > @flow_sensor.flow_hits.each_with_index do |hit, i|
> >           if i > 4 # start with 3rd hit in db
> >               time_diff = hit[i].date_time.to_i -
> hit[i-3].date_time.to_i
> >               value_diff = hit[i].value - hit[i-3].value
> >               min = time_diff / 60
> >               val = value_diff / min
> >               plots.push(val)
> >               times.push(hit[i].date_time)
> >           end
> >         end
> >
> > is giving me a nil value evaluating nil.date_time
> >
> > this is for a rails app by the way.
> >
> > i know i have the models set up right, because other functions are
> > working.
> > thats why i think my structure is wrong.
> >
> > thanks.
> >
> >
>
> cool beans, thanks gents.
sk

------=_Part_60381_28670901.1166738359564--