Presented at Tokyo Web Mining

1. 2017 10 28
Web

3. Twitter: @hamukazu
Python 5

4. EC
ASP

5. • Scipy/Numpy
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7. scikit-learn TensorFlow
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8. Python
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Numpy
• Cython

9. s = 0
for i in range(1, 100000001):
s += i
print(s)
1 1

10. s = sum(range(1, 100000001))
print(s)

11. import numpy as np
a = np.arange(1, 100000001, dtype=np.int64)
print(a.sum())

12. s = 0
for i in range(1, 100000001):
s += i
print(s)
s = sum(range(1, 100000001))
print(s)
import numpy as np
a = np.arange(1, 100000001, dtype=np.int64)
print(a.sum())
30.21
12.33
0.38

13. Numpy
• Numpy
• Numpy
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14. Cython
• Python C
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• Numpy

15. Cython
def prime(n):
p = [True] * (n + 1)
m = 2
while m < n + 1:
if p[m]:
i = m * 2
while i < n + 1:
p[i] = False
i += m
m += 1
i = n
while not p[i]:
i -= 1
return i
n
p(10000000)
Python 4.75 Cython 3.04

16. def prime(n):
p = [True] * (n + 1)
m = 2
while m < n + 1:
if p[m]:
i = m * 2
while i < n + 1:
p[i] = False
i += m
m += 1
i = n
while not p[i]:
i -= 1
return i
def prime(int n):
cdef int i, m
p = [True] * (n + 1)
m = 2
while m < n + 1:
if p[m]:
i = m * 2
while i < n + 1:
p[i] = False
i += m
m += 1
i = n
while not p[i]:
i -= 1
return i
3.04 3.04

17. def prime(int n):
cdef int m, i
cdef int * p = <int * >malloc((n + 1) * sizeof(int))
for i in range(n + 1):
p[i] = 1
m = 2
while m < n + 1:
if p[m]:
i = m * 2
while i < n + 1:
p[i] = 0
i += m
m += 1
i = n
while not p[i]:
i -= 1
free(p)
return i
3.04 0.17
C

18. Cython
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19. http://bit.ly/kimikazu20140913 http://bit.ly/kimikazu20160204
Python
PyCon JP 2014 2016

20. …
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22. Premature optimization is the root of all evil.
— Donald Knuth

24. •
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• XP
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25. •
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26. •
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27. XP
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• ☓ ○
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28. •
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29. Scikit-learn
SpectralClustering

30. •
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31. XT
X

32. •
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33. x
Softplus f(x) = log(1 + ex
)
f(x) ⇡ x
f(1000)

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35. • Python
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