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Probabilistic data structures

Project description

Probabilistic Structures

Probstructs is easy to use Python wrapper for C++ library probstructs . It supports Exponential Histograms, Count Min Sketch (CM-Sketch), and Exponential Count Min Sketch (ECM-Sketch).

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With pip:

pip install probstructs

From source:

pip install .



Count–min sketch (CM sketch) is a probabilistic data structure that serves as a frequency table of events in a stream of data. It uses hash functions to map events to frequencies, but unlike a hash table uses only sub-linear space, at the expense of overcounting some events due to collisions.

C++ documentation:

from probstructs import CountMinSketch

cm_sketch = CountMinSketch(100, 4)"aaa", 1)"bbb", 5)"aaa", 2)

# 3
# 5
# 0

cm_sketch = CountMinSketch(width=100, depth=4)"bbb", delta=5)
# 5


Exponential histogram (EH) is a probabilistic data structure that serves as a frequency counter for specific elements in the last N elements from stream..

C++ documentation:

from probstructs import ExponentialHistorgram

eh = ExponentialHistorgram(1), 1)
print(eh.get(1, 1))
# 1, 1)
print(eh.get(1, 1))
# 2, 1)
print(eh.get(1, 2))
# 1

eh = ExponentialHistorgram(window=1), delta=1)
print(eh.get(window=1, tick=1))
# 1, delta=1)
print(eh.get(window=1, tick=1))
# 2, delta=1)
print(eh.get(window=1, tick=2))
# 1


Exponential count-min sketch (ECM-Sketch) combines CM-Sketch with EH to count number of different elements in the last N elements in the stream.

C++ documentation:

from probstructs import ExponentialCountMinSketch

ecm_sketch = ExponentialCountMinSketch(100, 4, 8)

ts = 0"aaa", ts, 1)"bbb", ts, 4)"ccc", ts, 8)

print(ecm_sketch.get("aaa", 4, ts))
# 1
print(ecm_sketch.get("bbb", 4, ts))
# 4
print(ecm_sketch.get("ccc", 4, ts))
# 8
print(ecm_sketch.get("ddd", 4, ts))
# 0

ecm_sketch = ExponentialCountMinSketch(width=100, depth=4, window=8)

ts = 0"aaa", tick=ts, delta=1)"bbb", tick=ts, delta=4)"ccc", tick=ts, delta=8)

print(ecm_sketch.get(key="aaa", window=4, tick=ts))
# 1
print(ecm_sketch.get(key="bbb", window=4, tick=ts))
# 4
print(ecm_sketch.get(key="ccc", window=4, tick=ts))
# 8
print(ecm_sketch.get(key="ddd", window=4, tick=ts))
# 0



  • Introduce named parameters

  • Update documentation to contain examples


  • Initial version

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