ざっとわかるPython

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ͬ͟ͱΘ͔Δ Python hakobe

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ൃදͷഎܠ • ͍ΖΜͳݴޠΛదࡐదॴͰ࢖͍͜ͳ͍ͨ͠  ΋ͷͰ͢Ͷ • Pythonʹ੎͍͕͋ΔͷͰ࢖͑ΔΑ͏ʹͳͬ ͯΔͱศརͦ͏ • ͬ͘͟Γௐ΂ͨͷͰͬ͘͟Γ঺հ͠·͢

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Python (ͬ͘͟Γ) • ൚༻εΫϦϓτݴޠ • ΠϯσϯτͰΞϨ͢Δ΍ͭ • 2ͱ3͕͋Δ • ࠷ۙΘΓͱਓؾ͕͕͋ͬͯΔ

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Python class Blog(): def __init__(self, id, owner_id, title): self.id = id self.owner_id = owner_id self.title = title def is_owned_by(self, user): return user.id == self.owner_id

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ࠓ೔ͷΰʔϧ:   Pythonͷงғؾ͕ͬ͟ͱΘ͔Δ ˒ ։ൃ؀ڥ ˒ Web։ൃ ˒ σʔλ෼ੳ ˒ ݴޠͷਐԽ ˒ ίϛϡχςΟ

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։ൃ؀ڥ

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Python 2? 3? • Python3 Λ࢖͑͹OK • ۙ೥ϥΠϒϥϦ΋ἧ͖ͬͯͨ • Python2ܥ͸2020೥Ͱऴྃ • 2.7ܥ͕࠷ޙͷϦϦʔε

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Python3 Unicodeจࣈྻ ໰୊ 1. ৗʹ use utf8; ͞ΕΔΑ͏ʹͳͬͨ(Perl೴ 2. จࣈྻͱόΠτྻΛ·ͥΔͱྫ֎ʹͳΔ • ݕࡧΩʔϫʔυ: “python3 unicode ͳͥ”

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Python3ͷจࣈྻͷߟ͑ํ • ೖྗΛdecode/ग़ྗΛencode(஌ͬͯΔ΍ ͭ! # 外部からの入力はバイト列 in_bytes = b'\xf0\x9f\x8d\xa3' string = in_bytes.decode('utf-8') # バイト列にして外部に出力 out_bytes = string.encode('utf-8')

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खݩ؀ڥͷߏங • ݕࡧΩʔϫʔυ: “Python yamaguchi 2017” • ʙ؆୯3εςοϓʙ • pyenvͰॲཧܥΛ͍ΕΔ • python -m venv Ͱ؀ڥ੾Γସ͑Δ • pip ͰϥΠϒϥϦΛΠϯετʔϧ͢Δ ͿͬͪΌ͚ॾઆ͋Δ͚ͲखݩͰ͸͜ΕͰշద

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ϥΠϒϥϦ • ඪ४ϥΠϒϥϦ • Battery Included ํࣜͰॆ࣮ • https://docs.python.jp/3/library/ • CPANతͳ΍ͭ = PyPI • ඪ४ͷpip ίϚϯυͰΠϯετʔϧͰ͖Δ

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PyPI

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ΤσΟλ • ͍͍ͩͨPythonαϙʔτ͕͋ͬͯ҆৺ • ྑ͍IDE΋͋Δ: PyCharm • ࠷ۙࣗ෼͸Visual Studio CodeΛ࢖ͬͯΔ • linter΍ิ׬͕͙͢࢖͑ͯศར

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Linter • flake8Λ࢖͑͹͍͍ͩͨOK • ΍ͨΒLinterతϥΠϒϥϦ͕ଟ͍ • pycodestyle, pydocstyle, pyflake, flake8, hacking … • autopep8 ॻ͖׵͑ͯ͘ΕΔ΍ͭ΋͋Δ

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ﬂake8 • pycodestyle + pyﬂake > flake8 enjoy.py enjoy.py:1:1: F401 'os' imported but unused enjoy.py:3:1: E302 expected 2 blank lines, found 1 enjoy.py:4:5: F841 local variable 'i' is assigned to but never used enjoy.py:9:5: E303 too many blank lines (2)

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Test VOJUUFTU ඪ४ఴ෇ɺඞཁे෼ QZUFTU ׆ൃɺΑ͘࢖ΘΕͯΔɺQPXFSBTTFSU OPTF ੲ͸੎͍͕͋ͬͨΒ͍͠

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py.test def inc(x): return x + 1 def test_answer(): assert inc(3) == 5 def test_misc(): assert [1,2,3,4], [1,2,3,4] assert isinstance('hello', str)

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pytest ͷ࣮ߦ݁Ռ ================== FAILURES =================== _________________ test_answer _________________ def test_answer(): > assert inc(3) == 5 E assert 4 == 5 E + where 4 = inc(3) test_pyt.py:5: AssertionError ===== 1 failed, 1 passed in 0.06 seconds ======

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TestࢧԉϥΠϒϥϦ • freezegun = Test::TimeΈ͍ͨͳ΍ͭ from freezegun import freeze_time import datetime def test_time(): with freeze_time("2020-06-06"): assert datetime.datetime.now() == \ datetime.datetime(2020, 6, 6)

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Web։ൃ

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WebϑϨʔϜϫʔΫ 'MBTL "NPOతͳܰྔλΠϓ %KBOHP 3BJMTతͳΜͰ΋͍ΓϦονλΠϓ 1ZSBNJE ద౓ͳ͓΋ͯͳ͠

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Flask from flask import (Flask, request, redirect) web = Flask(__name__) @web.route('//edit', methods=['POST']) def edit(): title = request.form['title'] body = request.form['body'] entry = create(title, body) return redirect('/entry/' + entry.id)

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WSGI • αʔόͱΞϓϦέʔγϣϯؒͷϓϩτίϧ • PSGIͷܑ͓͞Μ def app(environ, start_response): start_response( '200 OK', [('Content-Type', 'text/plain')] ) yield b'Hello World\n’

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HTTPαʔό • جຊ͸ prefork worker model • uWSGI͸thread΋࢖͑ΔͬΆ͍? V84(* ࠷ۙྲྀߦΓͰଟػೳ (VOJDPSO 3VCZͷΞϨ༝དྷͰγϯϓϧ

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σʔλϕʔε • DB͝ͱͷϥΠϒϥϦ: e.g. mysqlclient • API͸PEP 249Ͱඪ४Խ (DBI+DBD) import MySQLdb conn = MySQLdb.connect(db='enjoy') with conn.cursor() as cursor: cursor.execute('SELECT UUID_SHORT() as uuid') print(cursor.fetchone().get('uuid'))

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ORM • DBϥΠϒϥϦΛͦͷ··࢖͏͘Β͍Ͱ΋ 42-"MDIFNZ ਓؾɻΫΤϦϏϧμతͳ࢖͍ํ΋ %KBOHP03. %KBOHP࢖͏ͳΒ

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ബ͍Web Appͷߏ੒Λࢼͯ͠Έͨ • hakobe/hakoblog-python • ബ͍WebϑϨʔϜϫʔΫ (Flask) • ORMͳ͠ (mysqlclientΛ௚ʹ࢖͏) • ServiceϨΠϠ • ςϯϓϨʔτΤϯδϯ͸ Jinja2

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ORM࢖Θͣʹૉ๿ʹ΍͍ͬͯ͘ class BlogLoader(): @classmethod def find_by_id(cls, db, blog_id): with db.cursor() as cursor: row = cursor.execute(''' SELECT id, owner_id, title FROM blog WHERE id = %s''', (blog_id, ) ).fetchone() return Blog(**row)

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ϔϧύΛఆ͍͍ٛͯ͠ײ͡ʹςετ def test_find_by_id(): "EntryLoader.find_by_id() can find a entry by id" db = DB() entry = create_entry() found_entry = EntryLoader.find_by_id(db, entry.id) assert isinstance(found_entry, Entry) assert found_entry.id == entry.id

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σʔλղੳ

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σʔλղੳϥΠϒϥϦ • ͱʹ͔͘ॆ࣮ͯ͠Δ ɹ ͷΩϥʔίϯςϯπ • numpy • scipy • scikit-learn • pandas • matplotlib • Jupyter notebook • σʔλղੳ͍ͨ͠ਓ͕ू·͍ͬͯͯ޷॥؀

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Numpy • ΊͬͪΌߴ଎ʹߦྻԋࢉͰ͖Δ΍ͭ • ߦྻ಺ͷσʔλܕΛ౷Ұ͢Δ͜ͱͰC΍ FortranͰߴ଎ʹԋࢉՄೳʹͯ͠Δ

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Numpy import numpy as np m1 = np.array([ [1, 2, 3], [4, 5, 6], ]) m2 = np.array([ [ 7, 8, 9], [10, 11, 12], ]) m1.dot(m2.T) np.zeros([2, 3]) # array([[ 0., 0., 0.], # [ 0., 0., 0.]]) np.identity(2) # array([[ 1., 0.], # [ 0., 1.]]) np.arange(10).reshape(2,5) # array([[0, 1, 2, 3, 4], # [5, 6, 7, 8, 9]])

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Scipy • NumpyϕʔεͷศརͳՊֶܭࢉάοζू • ౷ܭͱ͔ઢܗ୅਺ͱ͔৴߸ॲཧͱ͔?? • ౷ܭάοζ͸ABςετͷݕఆͱ͔ʹ࢖͑Δ

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Scipy • ࢀߟ: A/Bςετʹ༻͍ΒΕΕΔ౷ܭతݕఆ ख๏ʢϩδοΫʣͷ·ͱΊˍൺֱ import scipy import scipy.stats data = [ # click, access [ 150, 500120 ], # A [ 70, 320050 ], # B ] chi2, p, dof, expected = scipy.stats.chi2_contingency(data) print(p) # 0.0339

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scikit-learn • σʔλ෼ੳ/σʔλϚΠχϯά ϥΠϒϥϦू • ධՁͷͨΊͷศརάοζ΋ • ͰػցֶशΤϯδχΞͷؾ෼ʹͳΕΔ from sklearn import svm svc = svm.SVC() svc.fit(X, y) svc.predict(Xtest)

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pandas • σʔλղੳϥΠϒϥϦ • ϝϞϦ্ͷσʔλʹରͯ͠SQLΈ͍ͨʹ  σʔλΛϑΟϧλͨ͠Γू໿ͨ͠ΓͰ͖Δ • ௐࠪܥͷλεΫͰศར౓͕ߴ͍

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matplotlib • σϑΝΫτͷάϥϑඳըϥΠϒϥϦ • ͍͍ͩͨͳΜͰ΋Ͱ͖ͯศར • API͕Ή͍ͣͷͰ୅ସϥΠϒϥϦ͕ຄڵ͍ͯ͠ Δͱ͔ • ݕࡧΩʔϫʔυ: “matplotlib alternative”

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Jupyter notebook • REPLͷ͓Խ͚(ݩIPython) • ίʔυΛ࣮ߦͨ͠Γ࣮ߦ݁ՌΛදࣔͨ͠Γ  આ໌Λॻ͍ͨΓͰ͖ΔWebΞϓϦ • ΊͪΌͪ͘Όࢼߦࡨޡ͠΍͍͢ • ͳΊ͚ͯͨͲ࣮ࡍ͔ͭ͏ͱ͛͢ʔࢼߦࡨޡ͠ ΍͍͢…

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ݴޠͷਐԽ

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ܕΞϊςʔγϣϯ • ؔ਺΍ม਺ͷܕΛ෦෼తʹهड़Ͱ͖Δ • Generics΍Structual subtyping΋ • ݴޠػೳͱͯ͠͸ΞϊςʔγϣϯͷΈ • ͋͘·Ͱ΋ಈతܕ෇͚͕ओ • Smart::Argsͷ͍͍΍ͭ͘Β͍

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ࣗ࡞ﬁlterؔ਺΁ͷܕ෇͚ from typing import List, Callable, TypeVar T = TypeVar('T') def even(n: int) -> bool: return n % 2 == 0 def filter(l: List[T], f: Callable[[T], bool]) -> List[T]: result: List[T] = [] for e in l: if f(e): result.append(e) return result filter(['a', 'b', 'c'], even)

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mypy • ܕΞϊςʔγϣϯΛ࢖͏ܕνΣοΧʔ࣮૷ > mypy filter.py filter.py:14: error: Argument 2 to "filter" has incompatible type Callable[[int], bool]; expected Callable[[str], bool]

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typeshed • TypeScriptͷDeﬁnitelyTypedΈ͍ͨͳ  ܕఆٛϦϙδτϦ • .pyi ͱ͍͏֦ுࢠͰఆٛΛ͚ͩΛಡΈࠐΉ  ࢓૊Έ͕͋Δ • https://github.com/python/typeshed

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asyncio • ࠷ۙ࢖͑Δඪ४ϥΠϒϥϦ (Python 3.4 ~ • ਺͋ΔඇಉظϥΠϒϥϦΛ౷Ұ • ཁ͸AnyEvent(Perl೴ • ೿ੜϥΠϒϥϦ΋ग़͖ͯͯΔ: e.g. aiohttp • ߏจʹ૊Έࠐ·Εͨ (Python 3.6 ~

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asyncio ͱ async/await ߏจ import aiohttp import asyncio async def fetch(session, url): with aiohttp.Timeout(10, loop=session.loop): async with session.get(url) as response: return await response.text() async def main(loop): async with aiohttp.ClientSession(loop=loop) as session: html = await fetch(session, 'http://python.org') loop = asyncio.get_event_loop() loop.run_until_complete(main(loop))

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ίϛϡχςΟ

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ίϛϡχςΟ • ࣮͸͋Μ·Γ஌Βͳ͍… ڭ͍͑ͯͩ͘͞ʂ • PyCon ͸͍͢͝੝Γ্͕ͬͯ·͢Ͷʂʂ

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࢖ΘΕͯΔ҆৺ײ • اۀ • fastly/Google/redhat/Microsoft ͳͲ.. • ࠷৽ٕज़/اۀϥΠϒϥϦ • AWS/Google/Swaggerͱ͔.. • ڭҭ • Raspberry Pi

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·ͱΊ

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·ͱΊ • PythonงғؾΛͬ͘͟Γ঺հ • ݁ہPython͸Ͳ͏ͳΜ? • ศརͳ৔໘Ͱ͸࢖͍ͬͯͬͨΒ͑͑ΜͪΌ͏ • ͍ΖΜͳ͜ͱ͕Ͱ͖ΔΑ͏ʹɺPython΋  ࢖͍͜ͳͤΔͱྑ͍Ͱ͢Ͷʂ