| Loop through arrays with different names [message #55088] |
Wed, 01 August 2007 17:04  |
hazel
Messages: 5
Registered: July 2007
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Junior Member |
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Hello,
I have a really simple problem that always happens when I starting
trying to use strings..
I want to loop through a series of arrays, each with a slightly
different name (det1arr(n,3), det2arr(n,3), det3arr(n,3)..etc..) and
subject each to the same function:
a quick outline is:
for j=1,8 do begin
for i=0, n-1 do begin
vx=det1arr(i, 0) ; where the 1 is effectively the value of 'j'
vy=det1arr(i, 1)
vz=det1arr(i, 2)
result(i,j)=some_function(vx, vy, vz)
endfor
So can I do something like: vx=det+j+arr(i,0)? (Only that clearly
won't work)? There must be a way? Otherwise I can reload all my
different arrays into one array I realise and just loop through that.
I'm sure it's something painfully simple and for that I apologise, but
it is the end of the day (for me anyway),
Thanks,
Hazel
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| Re: Loop through arrays with different names [message #55171 is a reply to message #55088] |
Thu, 02 August 2007 08:55  |
hazel
Messages: 5
Registered: July 2007
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Junior Member |
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On Aug 2, 7:27 am, greg.a...@googlemail.com wrote:
> On Aug 2, 2:04 am, hazel <hazel.ken...@gmail.com> wrote:
>
>
>
>> Hello,
>
>> I have a really simple problem that always happens when I starting
>> trying to use strings..
>
>> I want to loop through a series of arrays, each with a slightly
>> different name (det1arr(n,3), det2arr(n,3), det3arr(n,3)..etc..) and
>> subject each to the same function:
>
>> a quick outline is:
>
>> for j=1,8 do begin
>
>> for i=0, n-1 do begin
>
>> vx=det1arr(i, 0) ; where the 1 is effectively the value of 'j'
>> vy=det1arr(i, 1)
>> vz=det1arr(i, 2)
>
>> result(i,j)=some_function(vx, vy, vz)
>
>> endfor
>
>> So can I do something like: vx=det+j+arr(i,0)? (Only that clearly
>> won't work)? There must be a way? Otherwise I can reload all my
>> different arrays into one array I realise and just loop through that.
>
>> I'm sure it's something painfully simple and for that I apologise, but
>> it is the end of the day (for me anyway),
>
>> Thanks,
>
>> Hazel
>
> I'd vote for putting them in a single array. I'm pretty sure this will
> turn out the cleanest option. You can put them together like this:
>
> detarr=[[[det1arr]],[[det2arr]],... ]
>
> although it would likely be better to create them in a detarr(n,3,8)
> in the first place. You may find that you can carry out your entire
> calculation as an operation on the array, rather than chugging through
> all the elements.
>
> regards,
> greg
Thank-you all for your useful suggestions, problem solved!
Hazel
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| Re: Loop through arrays with different names [message #55175 is a reply to message #55088] |
Thu, 02 August 2007 06:27 |
greg.addr
Messages: 160
Registered: May 2007
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Senior Member |
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On Aug 2, 2:04 am, hazel <hazel.ken...@gmail.com> wrote:
> Hello,
>
> I have a really simple problem that always happens when I starting
> trying to use strings..
>
> I want to loop through a series of arrays, each with a slightly
> different name (det1arr(n,3), det2arr(n,3), det3arr(n,3)..etc..) and
> subject each to the same function:
>
> a quick outline is:
>
> for j=1,8 do begin
>
> for i=0, n-1 do begin
>
> vx=det1arr(i, 0) ; where the 1 is effectively the value of 'j'
> vy=det1arr(i, 1)
> vz=det1arr(i, 2)
>
> result(i,j)=some_function(vx, vy, vz)
>
> endfor
>
> So can I do something like: vx=det+j+arr(i,0)? (Only that clearly
> won't work)? There must be a way? Otherwise I can reload all my
> different arrays into one array I realise and just loop through that.
>
> I'm sure it's something painfully simple and for that I apologise, but
> it is the end of the day (for me anyway),
>
> Thanks,
>
> Hazel
I'd vote for putting them in a single array. I'm pretty sure this will
turn out the cleanest option. You can put them together like this:
detarr=[[[det1arr]],[[det2arr]],... ]
although it would likely be better to create them in a detarr(n,3,8)
in the first place. You may find that you can carry out your entire
calculation as an operation on the array, rather than chugging through
all the elements.
regards,
greg
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| Re: Loop through arrays with different names [message #55176 is a reply to message #55088] |
Thu, 02 August 2007 06:00 |
mattf
Messages: 13
Registered: January 2007
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Junior Member |
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On Aug 2, 8:57 am, mattf <mfe...@earthlink.net> wrote:
> On Aug 1, 8:04 pm, hazel <hazel.ken...@gmail.com> wrote:
>
>
>
>> Hello,
>
>> I have a really simple problem that always happens when I starting
>> trying to use strings..
>
>> I want to loop through a series of arrays, each with a slightly
>> different name (det1arr(n,3), det2arr(n,3), det3arr(n,3)..etc..) and
>> subject each to the same function:
>
>> a quick outline is:
>
>> for j=1,8 do begin
>
>> for i=0, n-1 do begin
>
>> vx=det1arr(i, 0) ; where the 1 is effectively the value of 'j'
>> vy=det1arr(i, 1)
>> vz=det1arr(i, 2)
>
>> result(i,j)=some_function(vx, vy, vz)
>
>> endfor
>
>> So can I do something like: vx=det+j+arr(i,0)? (Only that clearly
>> won't work)? There must be a way? Otherwise I can reload all my
>> different arrays into one array I realise and just loop through that.
>
>> I'm sure it's something painfully simple and for that I apologise, but
>> it is the end of the day (for me anyway),
>
>> Thanks,
>
>> Hazel
>
> A somewhat more flexible approach is to collect the similar variables
> into a struct:
>
> det_struct = {d1:det1arr, d2:det2arr, ...}
>
> and then do a for-loop over the struct's fields
>
> n_fields = n_tags(det_struct)
> for ix_struct = 0, n_fields-1 do begin
> current_field = det_struct.(ix)
> for ix_var = 0, n do begin
> -- do whatever here --
> endfor
> endfor
Needless to say, I got the critical line wrong-- it should be
current_field = det_struct.(ix_struct)
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| Re: Loop through arrays with different names [message #55177 is a reply to message #55088] |
Thu, 02 August 2007 05:57 |
mattf
Messages: 13
Registered: January 2007
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Junior Member |
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On Aug 1, 8:04 pm, hazel <hazel.ken...@gmail.com> wrote:
> Hello,
>
> I have a really simple problem that always happens when I starting
> trying to use strings..
>
> I want to loop through a series of arrays, each with a slightly
> different name (det1arr(n,3), det2arr(n,3), det3arr(n,3)..etc..) and
> subject each to the same function:
>
> a quick outline is:
>
> for j=1,8 do begin
>
> for i=0, n-1 do begin
>
> vx=det1arr(i, 0) ; where the 1 is effectively the value of 'j'
> vy=det1arr(i, 1)
> vz=det1arr(i, 2)
>
> result(i,j)=some_function(vx, vy, vz)
>
> endfor
>
> So can I do something like: vx=det+j+arr(i,0)? (Only that clearly
> won't work)? There must be a way? Otherwise I can reload all my
> different arrays into one array I realise and just loop through that.
>
> I'm sure it's something painfully simple and for that I apologise, but
> it is the end of the day (for me anyway),
>
> Thanks,
>
> Hazel
A somewhat more flexible approach is to collect the similar variables
into a struct:
det_struct = {d1:det1arr, d2:det2arr, ...}
and then do a for-loop over the struct's fields
n_fields = n_tags(det_struct)
for ix_struct = 0, n_fields-1 do begin
current_field = det_struct.(ix)
for ix_var = 0, n do begin
-- do whatever here --
endfor
endfor
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| Re: Loop through arrays with different names [message #55182 is a reply to message #55088] |
Thu, 02 August 2007 00:03 |
Foldy Lajos
Messages: 268
Registered: October 2001
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Senior Member |
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On Thu, 2 Aug 2007, hazel wrote:
> So can I do something like: vx=det+j+arr(i,0)? (Only that clearly
> won't work)? There must be a way? Otherwise I can reload all my
> different arrays into one array I realise and just loop through that.
vx=(scope_varfetch('det'+strtrim(string(j), 1)+'arr'))[i,0]
regards,
lajos
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| Re: Loop through arrays with different names [message #55185 is a reply to message #55088] |
Wed, 01 August 2007 19:09 |
MarioIncandenza
Messages: 231
Registered: February 2005
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Senior Member |
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On Aug 1, 5:04 pm, hazel <hazel.ken...@gmail.com> wrote:
> So can I do something like: vx=det+j+arr(i,0)? (Only that clearly
> Otherwise I can reload all my
> different arrays into one array I realise and just loop through that.
What you want to do, if it's at all practical, is put everything into
a single 2D array and access it that way. If that's not practical, you
can do "kludge a" or "kludge b":
;kludge a
IDL> detarrsp=ptrarr(8)
IDL> detarrsp[0]=ptr_new(det1arr)
IDL> detarrsp[1]=ptr_new(det2arr)
; etc.
IDL> for j=0,7 do for i=0,n-1 do
result[i,j]=some_function((*detarrsp[j])[i,0:2])
; kludge b
IDL> for j=1,8 do for i=0,n-1 do success_or_failure= $
execute(string(i,j,j,i,format= $
'("result[",i,",",j,"]=some_function(det",i1.1,"arr[",i, ",
0:2])")'))
"Kludge B" is only for the most desperate of straits, and if it is
possible to put the data into a 2D array, you might as well avoid
"kludge a" as well.
Good luck,
Edward H.
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