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Специальные команды ipython
В IPython есть специальные команды, которые упрощают работу с интерпретатором. Все они начинаются со знака процента.
%history
Например, команда %history позволяет просмотреть историю введённых пользователем
команд в текущей сессии IPython:
In [1]: a = 10
In [2]: b = 5
In [3]: if a > b:
...: print("A is bigger")
...:
A is bigger
In [4]: %history
a = 10
b = 5
if a > b:
print("A is bigger")
%history
С помощью %history можно скопировать нужный блок кода.
%time
Команда %time показывает сколько секунд выполнялось выражение:
In [5]: import subprocess
In [6]: def ping_ip(ip_address):
..: reply = subprocess.run(['ping', '-c', '3', '-n', ip_address],
..: stdout=subprocess.PIPE,
..: stderr=subprocess.PIPE,
..: encoding='utf-8')
..: if reply.returncode == 0:
..: return True
..: else:
..: return False
..:
In [7]: %time ping_ip('8.8.8.8')
CPU times: user 0 ns, sys: 4 ms, total: 4 ms
Wall time: 2.03 s
Out[7]: True
In [8]: %time ping_ip('8.8.8')
CPU times: user 0 ns, sys: 8 ms, total: 8 ms
Wall time: 12 s
Out[8]: False
In [9]: items = [1, 3, 5, 7, 9, 1, 2, 3, 55, 77, 33]
In [10]: %time sorted(items)
CPU times: user 0 ns, sys: 0 ns, total: 0 ns
Wall time: 8.11 µs
Out[10]: [1, 1, 2, 3, 3, 5, 7, 9, 33, 55, 77]
Подробнее об IPython можно почитать в документации IPython.
Коротко информацию можно посмотреть в самом IPython командой %quickref:
IPython -- An enhanced Interactive Python - Quick Reference Card
===========================================================
obj?, obj?? : Get help, or more help for object (also works as
?obj, ??obj).
?foo.*abc* : List names in 'foo' containing 'abc' in them.
%magic : Information about IPython's 'magic' % functions.
Magic functions are prefixed by % or %%, and typically take their arguments
without parentheses, quotes or even commas for convenience. Line magics take a
single % and cell magics are prefixed with two %%.
Example magic function calls:
%alias d ls -F : 'd' is now an alias for 'ls -F'
alias d ls -F : Works if 'alias' not a python name
alist = %alias : Get list of aliases to 'alist'
cd /usr/share : Obvious. cd -<tab> to choose from visited dirs.
%cd?? : See help AND source for magic %cd
%timeit x=10 : time the 'x=10' statement with high precision.
%%timeit x=2**100
x**100 : time 'x**100' with a setup of 'x=2**100'; setup code is not
counted. This is an example of a cell magic.
System commands:
!cp a.txt b/ : System command escape, calls os.system()
cp a.txt b/ : after %rehashx, most system commands work without !
cp ${f}.txt $bar : Variable expansion in magics and system commands
files = !ls /usr : Capture sytem command output
files.s, files.l, files.n: "a b c", ['a','b','c'], 'a\nb\nc'
History:
_i, _ii, _iii : Previous, next previous, next next previous input
_i4, _ih[2:5] : Input history line 4, lines 2-4
exec _i81 : Execute input history line #81 again
%rep 81 : Edit input history line #81
_, __, ___ : previous, next previous, next next previous output
_dh : Directory history
_oh : Output history
%hist : Command history of current session.
%hist -g foo : Search command history of (almost) all sessions for 'foo'.
%hist -g : Command history of (almost) all sessions.
%hist 1/2-8 : Command history containing lines 2-8 of session 1.
%hist 1/ ~2/ : Command history of session 1 and 2 sessions before current.