| Re: zero-padding an array of arbitrary dimensionality (replacing execute in vm) [message #54894] |
Thu, 19 July 2007 09:37  |
Allan Whiteford
Messages: 117
Registered: June 2006
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Senior Member |
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Vince,
data=fltarr(43,45,23,12) ; <-- arbitrary
data[1,1,1,1]=1000. ; <-- so we know we get the right answer
tmp=size(data)
tmp=tmp[1:tmp[0]]
idx=1
for i=0,n_elements(tmp)-2 do idx=idx+product(tmp[0:i])
print,data[idx] ; We get element [1,1,1,1]
Helpful?
Probably doesn't work for 1D arrays.
Thanks,
Allan
hradilv wrote:
> I would like to zero-pad an array programmatically without knowing in
> advance what the dimensionality is of the array.
>
> For example, in 2D, for data = some fltarr (31,31) I could do
> dims = size(data,/dimensions)
> zpad = fltarr(dims[0]+1,dims[1]+1)
> zpad[1,1] = data
>
> For arb. dimensionality I have:
>
> dsize = size(data)
> ndim = dsize[0]
> dim = dsize[1:ndim]
> dtmp = make_array(dim+2,value=0,type=dsize[ndim+1])
>
> cmd = 'dtmp['
> for n=0L, ndim-1 do cmd = cmd+'1,'
> cmd = strmid(cmd,0,strlen(cmd)-1)+']=data'
> result = execute(cmd)
>
> But this won't work in the vm. So I need to somehow figure out the
> position of the [1,1,1,...] index for an arbitrary dimensionality.
>
> Clear enough? TIA!
> Vince
>
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| Re: zero-padding an array of arbitrary dimensionality (replacing execute in vm) [message #54984 is a reply to message #54894] |
Thu, 19 July 2007 15:11  |
Vince Hradil
Messages: 574
Registered: December 1999
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Senior Member |
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On Jul 19, 11:37 am, Allan Whiteford
<allan.rem...@phys.remove.strath.ac.remove.uk> wrote:
> Vince,
>
> data=fltarr(43,45,23,12) ; <-- arbitrary
> data[1,1,1,1]=1000. ; <-- so we know we get the right answer
>
> tmp=size(data)
> tmp=tmp[1:tmp[0]]
> idx=1
> for i=0,n_elements(tmp)-2 do idx=idx+product(tmp[0:i])
>
> print,data[idx] ; We get element [1,1,1,1]
>
> Helpful?
>
> Probably doesn't work for 1D arrays.
>
> Thanks,
>
> Allan
>
> hradilv wrote:
>> I would like to zero-pad an array programmatically without knowing in
>> advance what the dimensionality is of the array.
>
>> For example, in 2D, for data = some fltarr (31,31) I could do
>> dims = size(data,/dimensions)
>> zpad = fltarr(dims[0]+1,dims[1]+1)
>> zpad[1,1] = data
>
>> For arb. dimensionality I have:
>
>> dsize = size(data)
>> ndim = dsize[0]
>> dim = dsize[1:ndim]
>> dtmp = make_array(dim+2,value=0,type=dsize[ndim+1])
>
>> cmd = 'dtmp['
>> for n=0L, ndim-1 do cmd = cmd+'1,'
>> cmd = strmid(cmd,0,strlen(cmd)-1)+']=data'
>> result = execute(cmd)
>
>> But this won't work in the vm. So I need to somehow figure out the
>> position of the [1,1,1,...] index for an arbitrary dimensionality.
>
>> Clear enough? TIA!
>> Vince
Yes. I was just having some trouble wrapping my head around it.
Thanks!
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| Re: zero-padding an array of arbitrary dimensionality (replacing execute in vm) [message #54985 is a reply to message #54894] |
Thu, 19 July 2007 15:11 |
Michael Galloy
Messages: 1114
Registered: April 2006
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Senior Member |
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On Jul 19, 10:37 am, Allan Whiteford
<allan.rem...@phys.remove.strath.ac.remove.uk> wrote:
> data=fltarr(43,45,23,12) ; <-- arbitrary
> data[1,1,1,1]=1000. ; <-- so we know we get the right answer
>
> tmp=size(data)
> tmp=tmp[1:tmp[0]]
This is easier:
tmp = size(data, /dimensions)
> idx=1
> for i=0,n_elements(tmp)-2 do idx=idx+product(tmp[0:i])
>
> print,data[idx] ; We get element [1,1,1,1]
>
> Helpful?
That calculates the index, but I don't see how to use that. A straight-
forward
data[idx] = origArray
doesn't seem to work. Am I missing some other way to copy the original
array into the padded array?
It's ugly, but I think this should do the trick:
function zeropad, arr
compile_opt strictarr
on_error, 2
ndims = size(arr, /n_dimensions)
if (ndims lt 1) then message, 'must be an array'
padded = make_array(dimension=size(arr, /dimensions) + 2L, $
type=size(a, /type))
case ndims of
1 : padded[1] = arr
2 : padded[1, 1] = arr
3 : padded[1, 1, 1] = arr
4 : padded[1, 1, 1, 1] = arr
5 : padded[1, 1, 1, 1, 1] = arr
6 : padded[1, 1, 1, 1, 1, 1] = arr
7 : padded[1, 1, 1, 1, 1, 1, 1] = arr
8 : padded[1, 1, 1, 1, 1, 1, 1, 1] = arr
endcase
return, padded
end
Mike
--
www.michaelgalloy.com
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