<s>
ELKI	B-Language
(	O
for	O
Environment	B-Language
for	I-Language
DeveLoping	I-Language
KDD-Applications	I-Language
Supported	I-Language
by	I-Language
Index-Structures	I-Language
)	O
is	O
a	O
data	B-Application
mining	I-Application
(	O
KDD	O
,	O
knowledge	B-Application
discovery	I-Application
in	I-Application
databases	I-Application
)	O
software	B-Architecture
framework	I-Architecture
developed	O
for	O
use	O
in	O
research	O
and	O
teaching	O
.	O
</s>
<s>
It	O
was	O
originally	O
at	O
the	O
database	B-Application
systems	I-Application
research	O
unit	O
of	O
Professor	O
Hans-Peter	O
Kriegel	O
at	O
the	O
Ludwig	O
Maximilian	O
University	O
of	O
Munich	O
,	O
Germany	O
,	O
and	O
now	O
continued	O
at	O
the	O
Technical	O
University	O
of	O
Dortmund	O
,	O
Germany	O
.	O
</s>
<s>
It	O
aims	O
at	O
allowing	O
the	O
development	O
and	O
evaluation	O
of	O
advanced	O
data	B-Application
mining	I-Application
algorithms	O
and	O
their	O
interaction	O
with	O
database	B-Data_Structure
index	I-Data_Structure
structures	I-Data_Structure
.	O
</s>
<s>
The	O
ELKI	B-Language
framework	O
is	O
written	O
in	O
Java	B-Language
and	O
built	O
around	O
a	O
modular	O
architecture	O
.	O
</s>
<s>
Most	O
currently	O
included	O
algorithms	O
belong	O
to	O
clustering	B-Algorithm
,	O
outlier	B-Algorithm
detection	I-Algorithm
and	O
database	B-Data_Structure
indexes	I-Data_Structure
.	O
</s>
<s>
The	O
object-oriented	B-Language
architecture	I-Language
allows	O
the	O
combination	O
of	O
arbitrary	O
algorithms	O
,	O
data	O
types	O
,	O
distance	O
functions	O
,	O
indexes	O
,	O
and	O
evaluation	O
measures	O
.	O
</s>
<s>
The	O
Java	B-Language
just-in-time	O
compiler	O
optimizes	O
all	O
combinations	O
to	O
a	O
similar	O
extent	O
,	O
making	O
benchmarking	O
results	O
more	O
comparable	O
if	O
they	O
share	O
large	O
parts	O
of	O
the	O
code	O
.	O
</s>
<s>
When	O
developing	O
new	O
algorithms	O
or	O
index	O
structures	O
,	O
the	O
existing	O
components	O
can	O
be	O
easily	O
reused	O
,	O
and	O
the	O
type	B-Language
safety	I-Language
of	O
Java	B-Language
detects	O
many	O
programming	O
errors	O
at	O
compile	O
time	O
.	O
</s>
<s>
ELKI	B-Language
has	O
been	O
used	O
in	O
data	O
science	O
for	O
example	O
to	O
cluster	O
sperm	O
whale	O
codas	O
,	O
phoneme	B-Language
clustering	B-Algorithm
,	O
for	O
anomaly	B-Algorithm
detection	I-Algorithm
in	O
spaceflight	O
operations	O
,	O
for	O
bike	O
sharing	O
redistribution	O
,	O
and	O
traffic	O
prediction	O
.	O
</s>
<s>
ELKI	B-Language
aims	O
at	O
providing	O
a	O
shared	O
codebase	O
with	O
comparable	O
implementations	O
of	O
many	O
algorithms	O
.	O
</s>
<s>
As	O
research	O
project	O
,	O
it	O
currently	O
does	O
not	O
offer	O
integration	O
with	O
business	B-General_Concept
intelligence	I-General_Concept
applications	O
or	O
an	O
interface	O
to	O
common	O
database	B-Application
management	I-Application
systems	I-Application
via	O
SQL	B-Language
.	O
</s>
<s>
The	O
copyleft	B-License
(	O
AGPL	B-Application
)	O
license	O
may	O
also	O
be	O
a	O
hindrance	O
to	O
an	O
integration	O
in	O
commercial	O
products	O
;	O
nevertheless	O
it	O
can	O
be	O
used	O
to	O
evaluate	O
algorithms	O
prior	O
to	O
developing	O
an	O
own	O
implementation	O
for	O
a	O
commercial	O
product	O
.	O
</s>
<s>
The	O
audience	O
are	O
students	O
,	O
researchers	O
,	O
data	O
scientists	O
,	O
and	O
software	B-General_Concept
engineers	I-General_Concept
.	O
</s>
<s>
ELKI	B-Language
is	O
modeled	O
around	O
a	O
database-inspired	O
core	O
,	O
which	O
uses	O
a	O
vertical	O
data	O
layout	O
that	O
stores	O
data	O
in	O
column	O
groups	O
(	O
similar	O
to	O
column	B-Application
families	I-Application
in	O
NoSQL	B-General_Concept
databases	I-General_Concept
)	O
.	O
</s>
<s>
This	O
database	O
core	O
provides	O
nearest	B-Algorithm
neighbor	I-Algorithm
search	I-Algorithm
,	O
range/radius	O
search	O
,	O
and	O
distance	O
query	O
functionality	O
with	O
index	B-Data_Structure
acceleration	I-Data_Structure
for	O
a	O
wide	O
range	O
of	O
dissimilarity	O
measures	O
.	O
</s>
<s>
k-nearest-neighbor	B-General_Concept
algorithm	I-General_Concept
,	O
local	B-Algorithm
outlier	I-Algorithm
factor	I-Algorithm
and	O
DBSCAN	B-Algorithm
)	O
can	O
be	O
implemented	O
easily	O
and	O
benefit	O
from	O
the	O
index	B-Data_Structure
acceleration	I-Data_Structure
.	O
</s>
<s>
The	O
database	O
core	O
also	O
provides	O
fast	O
and	O
memory	O
efficient	O
collections	O
for	O
object	O
collections	O
and	O
associative	O
structures	O
such	O
as	O
nearest	B-General_Concept
neighbor	I-General_Concept
lists	O
.	O
</s>
<s>
ELKI	B-Language
makes	O
extensive	O
use	O
of	O
Java	B-Language
interfaces	O
,	O
so	O
that	O
it	O
can	O
be	O
extended	O
easily	O
in	O
many	O
places	O
.	O
</s>
<s>
ELKI	B-Language
uses	O
a	O
service	B-Application
loader	I-Application
architecture	O
to	O
allow	O
publishing	O
extensions	O
as	O
separate	O
jar	B-Language
files	I-Language
.	O
</s>
<s>
ELKI	B-Language
uses	O
optimized	O
collections	O
for	O
performance	O
rather	O
than	O
the	O
standard	O
Java	B-Language
API	O
.	O
</s>
<s>
For	B-Language
loops	I-Language
for	O
example	O
are	O
written	O
similar	O
to	O
C++	O
iterators	O
:	O
</s>
<s>
In	O
contrast	O
to	O
typical	O
Java	B-Language
iterators	O
(	O
which	O
can	O
only	O
iterate	O
over	O
objects	O
)	O
,	O
this	O
conserves	O
memory	O
,	O
because	O
the	O
iterator	O
can	O
internally	O
use	O
primitive	O
values	O
for	O
data	O
storage	O
.	O
</s>
<s>
The	O
reduced	O
garbage	B-General_Concept
collection	I-General_Concept
improves	O
the	O
runtime	O
.	O
</s>
<s>
ELKI	B-Language
includes	O
data	O
structures	O
such	O
as	O
object	O
collections	O
and	O
heaps	O
(	O
for	O
,	O
e.g.	O
,	O
nearest	B-Algorithm
neighbor	I-Algorithm
search	I-Algorithm
)	O
using	O
such	O
optimizations	O
.	O
</s>
<s>
The	O
visualization	O
module	O
uses	O
SVG	B-Application
for	O
scalable	O
graphics	O
output	O
,	O
and	O
Apache	B-Language
Batik	I-Language
for	O
rendering	O
of	O
the	O
user	O
interface	O
as	O
well	O
as	O
lossless	O
export	O
into	O
PostScript	B-Language
and	O
PDF	B-Application
for	O
easy	O
inclusion	O
in	O
scientific	O
publications	O
in	O
LaTeX	B-Application
.	O
</s>
<s>
Exported	O
files	O
can	O
be	O
edited	O
with	O
SVG	B-Application
editors	O
such	O
as	O
Inkscape	B-Application
.	O
</s>
<s>
Since	O
cascading	B-Language
style	I-Language
sheets	I-Language
are	O
used	O
,	O
the	O
graphics	O
design	O
can	O
be	O
restyled	O
easily	O
.	O
</s>
<s>
Unfortunately	O
,	O
Batik	B-Language
is	O
rather	O
slow	O
and	O
memory	O
intensive	O
,	O
so	O
the	O
visualizations	O
are	O
not	O
very	O
scalable	O
to	O
large	O
data	O
sets	O
(	O
for	O
larger	O
data	O
sets	O
,	O
only	O
a	O
subsample	O
of	O
the	O
data	O
is	O
visualized	O
by	O
default	O
)	O
.	O
</s>
<s>
Version	O
0.4	O
,	O
presented	O
at	O
the	O
"	O
Symposium	O
on	O
Spatial	O
and	O
Temporal	O
Databases	B-Application
"	O
2011	O
,	O
which	O
included	O
various	O
methods	O
for	O
spatial	O
outlier	B-Algorithm
detection	I-Algorithm
,	O
won	O
the	O
conference	O
's	O
"	O
best	O
demonstration	O
paper	O
award	O
"	O
.	O
</s>
<s>
Cluster	B-Algorithm
analysis	I-Algorithm
:	O
</s>
<s>
Anomaly	B-Algorithm
detection	I-Algorithm
:	O
</s>
<s>
Version	O
0.1	O
(	O
July	O
2008	O
)	O
contained	O
several	O
Algorithms	O
from	O
cluster	B-Algorithm
analysis	I-Algorithm
and	O
anomaly	B-Algorithm
detection	I-Algorithm
,	O
as	O
well	O
as	O
some	O
index	O
structures	O
such	O
as	O
the	O
R*	B-Data_Structure
-tree	I-Data_Structure
.	O
</s>
<s>
The	O
focus	O
of	O
the	O
first	O
release	O
was	O
on	O
subspace	O
clustering	B-Algorithm
and	O
correlation	B-Algorithm
clustering	I-Algorithm
algorithms	O
.	O
</s>
<s>
Version	O
0.3	O
(	O
March	O
2010	O
)	O
extended	O
the	O
choice	O
of	O
anomaly	B-Algorithm
detection	I-Algorithm
algorithms	O
and	O
visualization	O
modules	O
.	O
</s>
<s>
Version	O
0.4	O
(	O
September	O
2011	O
)	O
added	O
algorithms	O
for	O
geo	O
data	B-Application
mining	I-Application
and	O
support	O
for	O
multi-relational	O
database	O
and	O
index	O
structures	O
.	O
</s>
<s>
Version	O
0.5	O
(	O
April	O
2012	O
)	O
focuses	O
on	O
the	O
evaluation	O
of	O
cluster	B-Algorithm
analysis	I-Algorithm
results	O
,	O
adding	O
new	O
visualizations	O
and	O
some	O
new	O
algorithms	O
.	O
</s>
<s>
Version	O
0.6	O
(	O
June	O
2013	O
)	O
introduces	O
a	O
new	O
3D	O
adaption	O
of	O
parallel	B-Application
coordinates	I-Application
for	O
data	O
visualization	O
,	O
apart	O
from	O
the	O
usual	O
additions	O
of	O
algorithms	O
and	O
index	O
structures	O
.	O
</s>
<s>
Version	O
0.7.5	O
(	O
February	O
2019	O
)	O
adds	O
additional	O
clustering	B-Algorithm
algorithms	I-Algorithm
,	O
anomaly	B-Algorithm
detection	I-Algorithm
algorithms	O
,	O
evaluation	O
measures	O
,	O
and	O
indexing	O
structures	O
.	O
</s>
<s>
Version	O
0.8	O
(	O
October	O
2020	O
)	O
adds	O
automatic	O
index	O
creation	O
,	O
garbage	B-General_Concept
collection	I-General_Concept
,	O
and	O
incremental	O
priority	O
search	O
,	O
as	O
well	O
as	O
many	O
more	O
algorithms	O
such	O
as	O
BIRCH	B-Algorithm
.	O
</s>
