Discussion:
Attributes on rows and columns?
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Joshua Orvis
2017-08-11 01:54:21 UTC
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I'm not sure if this is a good fit for HDF5, but we have data this is a
large matrix (50,000 columns by 100,000 rows) and have metadata associated
with each row and column. I see how to store metadata on the table as a
whole, and even on individual matrix cells (if they are named types), but
can't find examples of how to store metadata/attributes on columns or rows.
Is this possible?

Thanks -
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Francesc Alted
2017-08-11 15:28:05 UTC
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Hi Joshua,

Trying to fit a large matrix into a Table is not a good idea. For a matrix
I'd use a CArray (for immutable dimensions) or a EArray (the array can be
expanded in one dimension). The Table is more meant for hosting objects
with columns with heterogeneous types, while keeping the length of the
columns relatively low (say, < 10,000).

And no, you cannot store attributes on neither columns or rows, but rather
in the matrix as a whole. But you can always create a sibling array with
the metadata that you want to store.

Francesc
Post by Joshua Orvis
I'm not sure if this is a good fit for HDF5, but we have data this is a
large matrix (50,000 columns by 100,000 rows) and have metadata associated
with each row and column. I see how to store metadata on the table as a
whole, and even on individual matrix cells (if they are named types), but
can't find examples of how to store metadata/attributes on columns or
rows. Is this possible?
Thanks -
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Francesc Alted
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Joshua Orvis
2017-08-12 16:54:25 UTC
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Thank you for that response, which saves me from chasing down blind paths
and directs me where to look instead. I'll save any further follow up
until I've tried working through the CArray version.
Post by Francesc Alted
Hi Joshua,
Trying to fit a large matrix into a Table is not a good idea. For a
matrix I'd use a CArray (for immutable dimensions) or a EArray (the array
can be expanded in one dimension). The Table is more meant for hosting
objects with columns with heterogeneous types, while keeping the length of
the columns relatively low (say, < 10,000).
And no, you cannot store attributes on neither columns or rows, but rather
in the matrix as a whole. But you can always create a sibling array with
the metadata that you want to store.
Francesc
Post by Joshua Orvis
I'm not sure if this is a good fit for HDF5, but we have data this is a
large matrix (50,000 columns by 100,000 rows) and have metadata associated
with each row and column. I see how to store metadata on the table as a
whole, and even on individual matrix cells (if they are named types), but
can't find examples of how to store metadata/attributes on columns or
rows. Is this possible?
Thanks -
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Francesc Alted
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