| How to check for existence of an HDF5 group [message #90182] |
Sat, 07 February 2015 10:24  |
dg86
Messages: 118
Registered: September 2012
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Senior Member |
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Dear Folks,
I want to create new groups within an HDF5 file. Before creating a new group, however,
I'd like to check whether a group of the same name already exists. What's the right
way to do this?
Calling H5G_OPEN or H5G_GET_OBJINFO with a new group name throws an error.
I could write a wrapper routine that catches the error and returns a "group not found"
value but that seems kludgy.
H5_LIST returns a whole lot of information, which I suppose I could parse. That also seems
clunky.
Is there a more elegant solution? Something along the lines of FILE_TEST that works
for HDF5 groups (H5G_TEST, e.g.)?
All the best,
David
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| Re: How to check for existence of an HDF5 group [message #90185 is a reply to message #90182] |
Sun, 08 February 2015 01:39  |
markb77
Messages: 217
Registered: July 2006
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Senior Member |
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On Saturday, February 7, 2015 at 7:24:50 PM UTC+1, David Grier wrote:
> Dear Folks,
>
> I want to create new groups within an HDF5 file. Before creating a new group, however,
> I'd like to check whether a group of the same name already exists. What's the right
> way to do this?
>
> Calling H5G_OPEN or H5G_GET_OBJINFO with a new group name throws an error.
> I could write a wrapper routine that catches the error and returns a "group not found"
> value but that seems kludgy.
>
> H5_LIST returns a whole lot of information, which I suppose I could parse. That also seems
> clunky.
>
> Is there a more elegant solution? Something along the lines of FILE_TEST that works
> for HDF5 groups (H5G_TEST, e.g.)?
>
> All the best,
>
> David
hi David,
The way to do it is to use H5_LIST with the FILTER keyword.
Also, I have a routine for this in my library: wmb_h5_group_exists()
which can be found at http://www.github.com/superchromix/wmb_lib
best,
Mark
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| Re: How to check for existence of an HDF5 group [message #90186 is a reply to message #90185] |
Sun, 08 February 2015 17:24 |
dg86
Messages: 118
Registered: September 2012
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Senior Member |
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On Sunday, February 8, 2015 at 4:39:51 AM UTC-5, superchromix wrote:
> On Saturday, February 7, 2015 at 7:24:50 PM UTC+1, David Grier wrote:
>> Dear Folks,
>>
>> I want to create new groups within an HDF5 file. Before creating a new group, however,
>> I'd like to check whether a group of the same name already exists. What's the right
>> way to do this?
>>
>> Calling H5G_OPEN or H5G_GET_OBJINFO with a new group name throws an error.
>> I could write a wrapper routine that catches the error and returns a "group not found"
>> value but that seems kludgy.
>>
>> H5_LIST returns a whole lot of information, which I suppose I could parse. That also seems
>> clunky.
>>
>> Is there a more elegant solution? Something along the lines of FILE_TEST that works
>> for HDF5 groups (H5G_TEST, e.g.)?
>>
>> All the best,
>>
>> David
>
>
> hi David,
>
> The way to do it is to use H5_LIST with the FILTER keyword.
>
> Also, I have a routine for this in my library: wmb_h5_group_exists()
>
> which can be found at http://www.github.com/superchromix/wmb_lib
>
> best,
> Mark
Thanks for the pointer to your repository, Mark. I'll have to look through
the HDF5 routines closely. In the meanwhile, the following kludge is working
for me. I try to open the group, and catch the error if the group
doesn't exist. This is part of an object definition for storing multi-volume
video data in an HDF5 archive:
;;;;
function h5video::H5G_OPEN, loc_id, group
COMPILE_OPT IDL2, HIDDEN
catch, error
if (error ne 0L) then begin
return, 0L
catch, /cancel
endif
gid = h5g_open(loc_id, group)
return, gid
end
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