VS CodeのPythonエクステンションを使ったJupterNotebookは通常のJupyterNotebookより遅い
要点
VS Codeの拡張機能『Python』を導入すると、VS Code上で通常のJupyterNotebookと同様にIPythonファイルを編集し、実行することができるようになります。
しかし、いざそれを使ってみると普段より明らかに処理に時間がかかっているように思えたので、今回それを検証してみました。
結論としては、VS Code上で実行した場合の方が圧倒的に遅いということがわかりました。
実行環境
- macOS Mojave 10.14.6
- Python 3.7.5
- pipenv 2018.11.26
- Jupyter
- jupyter 1.0.0
- jupyter-client 5.3.4
- jupyter-console 6.0.0
- jupyter-contrib-core 0.3.3
- jupyter-contrib-nbextensions 0.5.1
- jupyter-core 4.6.1
- jupyter-highlight-selected-word 0.2.0
- jupyter-latex-envs 1.4.6
- jupyter-nbextensions-configurator 0.4.1
- jupytext 1.3.0
検証コード
%% import pandas as pd import numpy as np from pandas import DataFrame from sklearn.datasets import load_boston import matplotlib.pyplot as plt import seaborn as sns boston = load_boston() df = DataFrame(X, columns = boston.feature_names) df['PRICE'] = boston.target %% %%time plt.figure(facecolor='w') pd.plotting.scatter_matrix(df, figsize=(20,20)) filename = 'scatter-matrix.png' plt.savefig(filename, dpi=100, bbox_inches="tight", pad_inches=0.1) plt.show()
結果
VS Code上で実行した場合の方が3倍ほど時間が掛かる結果が得られました。
Case1: JupyterNotebook
CPU times: user 20.8 s, sys: 337 ms, total: 21.1 s Wall time: 19.9 s
Case2: JupyterNotebook with Python extention of VS Code
CPU times: user 56.2 s, sys: 1.12 s, total: 57.3 s Wall time: 1min 5s
IPython上でGIFを表示する
前提
ルートディレクトリに表示したいGIFファイルがある場合を想定します。
!ls sample_data sin_curve.gif
ちなみに上の「sin_curve.gif」を生成するコードはこんな感じ。
%%
!pip install animatplot
%%
"""
Introduction to animatplot
https://animatplot.readthedocs.io/en/latest/tutorial/getting_started..html#Basic-Animation
"""
import numpy as np
from matplotlib import pyplot as plt
import animatplot as amp
def main():
xs = np.linspace(0, 1, 50)
ts = np.linspace(0, 1, 20)
Xs = np.asarray([xs] * len(ts))
Ys = [np.sin(2 * np.pi * (xs + t)) for t in ts]
"""
# you can also write
Xs, Ts = np.meshgrid(xs, ts)
Ys = np.sin(2 * np.pi * (Xs + Ts))
"""
block = amp.blocks.Line(Xs, Ys)
anim = amp.Animation([block])
anim.save_gif("sin_curve")
plt.show()
if __name__ == '__main__':
main()
GIFを表示するコード
以下のコードでGIFを表示させることができる。
from IPython.core.interactiveshell import InteractiveShell
InteractiveShell.ast_node_interactivity = "all"
from IPython import display
from pathlib import Path
gifPath = Path("sin_curve.gif")
with open(gifPath,'rb') as f:
display.Image(data=f.read(), format='png')
Path("")の引数に対象のGIFファイルのPathを入れてれればおけまる。
参考
elegant way to display gif file in notebook? · Issue #10045 · ipython/ipython
ValueError: Integers to negative integer powers are not allowed.[Python][Numpy]
エラー内容
以下のように、負の数を指数とした累乗の計算でエラーが出た。
for num in np.arange(-5, 5): print(10**num) """ ValueError: Integers to negative integer powers are not allowed. """
「負の整数による整数のべき乗は許されない」とのこと。
解決策
Python標準のrangeメソッドを使う。
for num in range(-5, 5): print(10**num)
numpyでは負の整数による整数のべき乗はできない。
逆に言えば、整数でなければnumpyでも期待通りの動作をする：
for num in np.arange(-5, 5): print(10.**num)
numpyは整数型の癖の強さに定評がある。
SQL何もわからんな人へ捧げる『SQL Bolt』
SQLBolt - Learn SQL - Introduction to SQL
SQLをWeb上で学べる教材。記述したクエリの結果がリアルタイムに出力される。
以下、コードサンプルといくつかの演習問題に対する解答例。簡単すぎる問題は省略。
SQL Lesson 3: Queries with constraints (Pt. 2)
-- 1. Find all the Toy Story movies SELECT * FROM movies where title like '%Toy Story%' ; -- 3. Find all the movies (and director) not directed by John Lasseter SELECT * FROM movies where director not like '%John Lasseter%' ;
SQL Review: Simple SELECT Queries
SELECT * FROM north_american_cities where Country like 'United States' order by latitude ASC;
SQL Lesson 7: OUTER JOINs
-- Find the list of all buildings that have employees SELECT distinct e.building FROM employees e join Buildings b on b.building_name = e.building ; -- List all buildings and the distinct employee roles in each building (including empty buildings) SELECT distinct b.building_name, e.role FROM Buildings b left outer join employees e on b.building_name = e.building ;
SQL Lesson 8: A short note on NULLs
SELECT column, another_column, … FROM mytable WHERE column IS/IS NOT NULL AND/OR another_condition AND/OR …;
Exercise
-- Find the name and role of all employees who have not been assigned to a building SELECT * FROM employees where building is null ; -- Find the names of the buildings that hold no employees SELECT * FROM buildings b left outer join employees e on e.building = b.building_name where e.building is null ;
SQL Lesson 9: Queries with expressions
-- Example query with expressions SELECT particle_speed / 2.0 AS half_particle_speed FROM physics_data WHERE ABS(particle_position) * 10.0 > 500; -- Select query with expression aliases SELECT col_expression AS expr_description, … FROM mytable; -- Example query with both column and table name aliases SELECT column AS better_column_name, … FROM a_long_widgets_table_name AS mywidgets INNER JOIN widget_sales ON mywidgets.id = widget_sales.widget_id;
Exercise
-- List all movies and their combined sales in millions of dollars SELECT m.title, (b.domestic_sales + b.international_sales) / 1000000 FROM movies m left outer join Boxoffice b on b.movie_id = m.id ; -- List all movies that were released on even number years SELECT m.title FROM movies m left outer join Boxoffice b on b.movie_id = m.id where m.year % 2 = 0 ;
SQL Lesson 10: Queries with aggregates (Pt. 1)
-- Select query with aggregate functions over all rows SELECT AGG_FUNC(column_or_expression) AS aggregate_description, … FROM mytable WHERE constraint_expression;
Exercise
-- Find the longest time that an employee has been at the studio SELECT max(years_employed) FROM employees ; -- For each role, find the average number of years employed by employees in that role SELECT role, avg(years_employed) FROM employees group by role ; -- Find the total number of employee years worked in each building SELECT building, sum(years_employed) FROM employees group by building ;
SQL Lesson 11: Queries with aggregates (Pt. 2)
-- Select query with HAVING constraint SELECT group_by_column, AGG_FUNC(column_expression) AS aggregate_result_alias, … FROM mytable WHERE condition GROUP BY column HAVING group_condition;
Did you know? If you aren't using the
GROUP BYclause, a simpleWHEREclause will suffice.
Exercise
-- Find the number of Artists in the studio (without a HAVING clause) SELECT count(*) FROM employees where role = 'Artist' ; -- Find the number of Employees of each role in the studio SELECT role,count(*) FROM employees group by role ; -- Find the total number of years employed by all Engineers SELECT role,sum(Years_employed) FROM employees group by role having role = 'Engineer' ;
SQL Lesson 12: Order of execution of a Query
-- Complete SELECT query SELECT DISTINCT column, AGG_FUNC(column_or_expression), … FROM mytable JOIN another_table ON mytable.column = another_table.column WHERE constraint_expression GROUP BY column HAVING constraint_expression ORDER BY column ASC/DESC LIMIT count OFFSET COUNT;
Exercise
-- Find the number of movies each director has directed SELECT m.director, count(*) FROM movies m left outer join boxoffice b on b.movie_id = m.id group by director order by director ; -- Find the total domestic and international sales that can be attributed to each director SELECT m.director, sum(domestic_sales+international_sales) FROM movies m left outer join boxoffice b on b.movie_id = m.id group by director order by director ;
SQL Lesson 13: Inserting rows
-- Insert statement with values for all columns INSERT INTO mytable VALUES (value_or_expr, another_value_or_expr, …), (value_or_expr_2, another_value_or_expr_2, …), …; -- Insert statement with specific columns INSERT INTO mytable (column, another_column, …) VALUES (value_or_expr, another_value_or_expr, …), (value_or_expr_2, another_value_or_expr_2, …), …;
SQL Lesson 14: Updating rows
-- Update statement with values UPDATE mytable SET column = value_or_expr, other_column = another_value_or_expr, … WHERE condition;
Exercise
-- The director for A Bug's Life is incorrect, it was actually directed by John Lasseter update movies set director = 'John Lasseter' where title = "A Bug's Life"
- 文字列の中でシングルクォーテーション「'」を使う場合は全体の括弧はダブルクォーテーション「"」を使う
SQL Lesson 15: Deleting rows
-- Delete statement with condition DELETE FROM mytable WHERE condition;
delete from movies where director = 'Andrew Stanton'
SQL Lesson 16: Creating tables
-- Create table statement w/ optional table constraint and default value CREATE TABLE IF NOT EXISTS mytable ( column DataType TableConstraint DEFAULT default_value, another_column DataType TableConstraint DEFAULT default_value, … );
SQL Lesson 17: Altering tables
-- Altering table to add new column(s) ALTER TABLE mytable ADD column DataType OptionalTableConstraint DEFAULT default_value; -- Altering table to remove column(s) ALTER TABLE mytable DROP column_to_be_deleted; -- Altering table name ALTER TABLE mytable RENAME TO new_table_name;
-- Add a column named Aspect_ratio with a FLOAT data type to store the aspect-ratio each movie was released in. alter talbe movies add Aspect_ratio float; -- Add another column named Language with a TEXT data type to store the language that the movie was released in. Ensure that the default for this language is English. alter table movies add Language text default 'English';
SQL Lesson 18: Dropping tables
-- Drop table statement DROP TABLE IF EXISTS mytable;
SQL Lesson X: To infinity and beyond!
これでクリアです。お疲れさまでした！
Octave 5.1.0でpauseの挙動がおかしい
CouseraのStanford University Machine Learningクラス2週目の課題ex1「2.1 Plotting the Data」において、説明に従ってplotData.mを編集し、ex1を実行すると、Enterキーを押してもpauseのまま動かなくなる事案に遭遇した。
Running warmUpExercise ... 5x5 Identity Matrix: ans = Diagonal Matrix 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 Program paused. Press enter to continue.
調べてみたところ、どうやらOctave 5.1.0ではpause関数にバグあることに原因があるようだ。
下記の記事を参考に、新たにpause関数を定義することで解決した。
octave pause; not working properly. Forces to ctrl+c :( : octave
ex1.mの適当な箇所に次の内容を追記。
function pause
input('','s');
end
これでEnterキーを押すごとに処理が進行する。
Rubyで変数が定義されているか確認する
defined?
Rubyで変数が定義されているか確認するにはdefined?メソッドを使用する。defined?は引数として入れた変数やメソッドが定義済みであれば式の種別を表す文字列を返す。未定義であればnilを返す。
例
>> a = 1
>> defined? a
=> "local-variable"
>> hoge = nil
>> defined? hoge
=> "local-variable"
>> defined? poke
=> nil
>> defined? puts
=> "method"
>> defined? defined?
Traceback (most recent call last):
SyntaxError ((irb):10: syntax error, unexpected end-of-input)
defined? defined?
^
