<s>
Hierarchical	B-Application
Data	I-Application
Format	I-Application
(	O
HDF	O
)	O
is	O
a	O
set	O
of	O
file	O
formats	O
(	O
HDF4	B-Application
,	O
HDF5	B-Application
)	O
designed	O
to	O
store	O
and	O
organize	O
large	O
amounts	O
of	O
data	O
.	O
</s>
<s>
Originally	O
developed	O
at	O
the	O
U.S.	O
National	B-General_Concept
Center	I-General_Concept
for	I-General_Concept
Supercomputing	I-General_Concept
Applications	I-General_Concept
,	O
it	O
is	O
supported	O
by	O
The	O
HDF	O
Group	O
,	O
a	O
non-profit	O
corporation	O
whose	O
mission	O
is	O
to	O
ensure	O
continued	O
development	O
of	O
HDF5	B-Application
technologies	O
and	O
the	O
continued	O
accessibility	O
of	O
data	O
stored	O
in	O
HDF	O
.	O
</s>
<s>
In	O
keeping	O
with	O
this	O
goal	O
,	O
the	O
HDF	O
libraries	O
and	O
associated	O
tools	O
are	O
available	O
under	O
a	O
liberal	O
,	O
BSD-like	B-Operating_System
license	I-Operating_System
for	O
general	O
use	O
.	O
</s>
<s>
The	O
freely	O
available	O
HDF	O
distribution	O
consists	O
of	O
the	O
library	O
,	O
command-line	O
utilities	O
,	O
test	O
suite	O
source	O
,	O
Java	B-Language
interface	O
,	O
and	O
the	O
Java-based	O
HDF	O
Viewer	O
(	O
HDFView	O
)	O
.	O
</s>
<s>
The	O
current	O
version	O
,	O
HDF5	B-Application
,	O
differs	O
significantly	O
in	O
design	O
and	O
API	B-Application
from	O
the	O
major	O
legacy	O
version	O
HDF4	B-Application
.	O
</s>
<s>
The	O
quest	O
for	O
a	O
portable	O
scientific	O
data	O
format	O
,	O
originally	O
dubbed	O
AEHOO	O
(	O
All	O
Encompassing	O
Hierarchical	O
Object	O
Oriented	O
format	O
)	O
began	O
in	O
1987	O
by	O
the	O
Graphics	O
Foundations	O
Task	O
Force	O
(	O
GFTF	O
)	O
at	O
the	O
National	B-General_Concept
Center	I-General_Concept
for	I-General_Concept
Supercomputing	I-General_Concept
Applications	I-General_Concept
(	O
NCSA	O
)	O
.	O
</s>
<s>
HDF4	B-Application
is	O
the	O
older	O
version	O
of	O
the	O
format	O
,	O
although	O
still	O
actively	O
supported	O
by	O
The	O
HDF	O
Group	O
.	O
</s>
<s>
It	O
supports	O
a	O
proliferation	O
of	O
different	O
data	O
models	O
,	O
including	O
multidimensional	O
arrays	O
,	O
raster	B-Algorithm
images	I-Algorithm
,	O
and	O
tables	O
.	O
</s>
<s>
Each	O
defines	O
a	O
specific	O
aggregate	O
data	O
type	O
and	O
provides	O
an	O
API	B-Application
for	O
reading	O
,	O
writing	O
,	O
and	O
organizing	O
the	O
data	O
and	O
metadata	O
.	O
</s>
<s>
The	O
HDF4	B-Application
format	O
has	O
many	O
limitations	O
.	O
</s>
<s>
Supporting	O
many	O
different	O
interface	O
styles	O
(	O
images	O
,	O
tables	O
,	O
arrays	O
)	O
leads	O
to	O
a	O
complex	O
API	B-Application
.	O
</s>
<s>
Perhaps	O
most	O
importantly	O
,	O
the	O
use	O
of	O
32-bit	O
signed	O
integers	O
for	O
addressing	O
limits	O
HDF4	B-Application
files	O
to	O
a	O
maximum	O
of	O
2	O
GB	O
,	O
which	O
is	O
unacceptable	O
in	O
many	O
modern	O
scientific	O
applications	O
.	O
</s>
<s>
The	O
HDF5	B-Application
format	O
is	O
designed	O
to	O
address	O
some	O
of	O
the	O
limitations	O
of	O
the	O
HDF4	B-Application
library	O
,	O
and	O
to	O
address	O
current	O
and	O
anticipated	O
requirements	O
of	O
modern	O
systems	O
and	O
applications	O
.	O
</s>
<s>
In	O
2002	O
it	O
won	O
an	O
R&D	O
100	O
Award	O
.	O
</s>
<s>
HDF5	B-Application
simplifies	O
the	O
file	O
structure	O
to	O
include	O
only	O
two	O
major	O
types	O
of	O
object	O
:	O
</s>
<s>
In	O
fact	O
,	O
resources	O
in	O
an	O
HDF5	B-Application
file	O
can	O
be	O
accessed	O
using	O
the	O
POSIX-like	O
syntax	O
/path/to/resource	O
.	O
</s>
<s>
More	O
complex	O
storage	O
APIs	B-Application
representing	O
images	O
and	O
tables	O
can	O
then	O
be	O
built	O
up	O
using	O
datasets	O
,	O
groups	O
and	O
attributes	O
.	O
</s>
<s>
In	O
addition	O
to	O
these	O
advances	O
in	O
the	O
file	O
format	O
,	O
HDF5	B-Application
includes	O
an	O
improved	O
type	O
system	O
,	O
and	O
dataspace	O
objects	O
which	O
represent	O
selections	O
over	O
dataset	O
regions	O
.	O
</s>
<s>
The	O
API	B-Application
is	O
also	O
object-oriented	O
with	O
respect	O
to	O
datasets	O
,	O
groups	O
,	O
attributes	O
,	O
types	O
,	O
dataspaces	O
and	O
property	O
lists	O
.	O
</s>
<s>
The	O
latest	O
version	O
of	O
NetCDF	B-Application
,	O
version	O
4	O
,	O
is	O
based	O
on	O
HDF5	B-Application
.	O
</s>
<s>
Because	O
it	O
uses	O
B-trees	B-Architecture
to	O
index	O
table	O
objects	O
,	O
HDF5	B-Application
works	O
well	O
for	O
time	O
series	O
data	O
such	O
as	O
stock	O
price	O
series	O
,	O
network	O
monitoring	O
data	O
,	O
and	O
3D	O
meteorological	O
data	O
.	O
</s>
<s>
The	O
bulk	O
of	O
the	O
data	O
goes	O
into	O
straightforward	O
arrays	O
(	O
the	O
table	O
objects	O
)	O
that	O
can	O
be	O
accessed	O
much	O
more	O
quickly	O
than	O
the	O
rows	O
of	O
an	O
SQL	B-Language
database	I-Language
,	O
but	O
B-tree	B-Architecture
access	O
is	O
available	O
for	O
non-array	O
data	O
.	O
</s>
<s>
The	O
HDF5	B-Application
data	O
storage	O
mechanism	O
can	O
be	O
simpler	O
and	O
faster	O
than	O
an	O
SQL	B-Language
star	B-Application
schema	I-Application
.	O
</s>
<s>
Criticism	O
of	O
HDF5	B-Application
follows	O
from	O
its	O
monolithic	O
design	O
and	O
lengthy	O
specification	O
.	O
</s>
<s>
HDF5	B-Application
does	O
not	O
enforce	O
the	O
use	O
of	O
UTF-8	O
,	O
so	O
client	O
applications	O
may	O
be	O
expecting	O
ASCII	O
in	O
most	O
places	O
.	O
</s>
<s>
Go	B-Application
-	O
'	O
s	O
package	O
.	O
</s>
<s>
enables	O
users	O
to	O
manage	O
HDF5	B-Application
files	O
through	O
a	O
high-level	O
language	O
(	O
similar	O
to	O
SQL	B-Language
)	O
in	O
C	B-Language
,	O
C++	B-Language
,	O
Java	B-Language
,	O
Python	B-Language
,	O
C#	O
,	O
Fortran	B-Application
and	O
R	B-Language
.	O
</s>
<s>
IGOR	B-Application
Pro	I-Application
offers	O
files	O
.	O
</s>
<s>
JSON	B-General_Concept
through	O
.	O
</s>
<s>
Julia	B-Application
provides	O
HDF5	B-Application
support	O
through	O
the	O
package	O
.	O
</s>
<s>
LabVIEW	B-Application
can	O
gain	O
HDF	O
support	O
through	O
third-party	O
libraries	O
,	O
such	O
as	O
and	O
.	O
</s>
<s>
Lua	B-Language
through	O
the	O
library	O
.	O
</s>
<s>
Python	B-Language
supports	O
HDF5	B-Application
via	O
(	O
both	O
high	O
-	O
and	O
low-level	O
access	O
to	O
HDF5	B-Application
abstractions	O
)	O
and	O
via	O
(	O
a	O
high-level	O
interface	O
with	O
advanced	O
indexing	O
and	O
database-like	O
query	O
capabilities	O
)	O
.	O
</s>
<s>
HDF4	B-Application
is	O
available	O
via	O
and/or	O
for	O
both	O
Python	B-Language
2	O
and	O
Python	B-Language
3	O
.	O
</s>
<s>
The	O
popular	O
data	O
manipulation	O
package	O
pandas	B-Application
can	O
import	O
from	O
and	O
export	O
to	O
HDF5	B-Application
via	O
.	O
</s>
<s>
R	B-Language
offers	O
support	O
in	O
the	O
and	O
packages	O
.	O
</s>
<s>
HDF5	B-Application
Plugin	O
for	O
Apache	O
Drill	O
enables	O
SQL	B-Language
Queries	O
over	O
HDF5	B-Application
Files	O
.	O
</s>
