scienceoss.com » help

History: keep track of your work in IPython

ryan — Sun, 02 Dec 2007 17:23:10 +0000

This post shows the different ways of keeping track of your work in IPython: the command history, saving the history (or parts of the history to file) for later use, and storing variables so you don’t have to create them next time you use IPython.

History

Note: In the history, you may see _ip.magic(). This is the wrapper used to run magic commands

In[5]:	The prompt shows the number of the command in the history
In[3]	The list, In, contains the history. So this command shows the third item in the history (item 0 is a newline)
Out.keys()	The output cache, Out, is a dictionary. Use this to see the keys in the output cache
_i	show the last command
_ii	show the second-to-last command
_iii	show the third-to-last command (and so on)
_i10	show the tenth command in history (same as In[10])
exec _i	execute the last command
exec _i4	execute the fourth command in the history
hist	display the last 20 or so commands
hist 100	display the last 100 commands
hist 3 10	display commands 3 through 10 in the history
hist -r	hide the wrappers around magic commands
macro mac 1-4 7	create a macro called mac out of lines 1, 2, 3, 4, and 7 of the history
mac	runs the macro called mac
print mac	prints the commands in "c">mac
store mac	stores the macro in the profile, it will be available next time you start IPython

store x	store x in the profile. It will be loaded next time you start IPython.
store x > /tmp/a.txt	store x in the file, a.txt
store -r	restore into the workspace the variables that have been stored. Overwrites exisiting variables in workspace.
store -d x	delete just x from storage
store -z	remove ALL variables from storage

Logging your session for later use

logstate	show state of the logger (on or off)
logstart	start logging (default log file is ipython_log.py, in the present working directory
logstart filename	store history up to this point, and continue logging history, in filename
logstart -r filename	same as above, but use the raw input: don’t put the _ip.magic() wrapper around magic commands
logon	start logging after stopping
logoff	stop logging after starting
runlog log1 log2	run the log file log1, then run the log file log2 (this executes the logged histories)

Managing variables in IPython

ryan — Sun, 02 Dec 2007 17:18:02 +0000

After working in IPython for a while, sometimes you’d like to use a variable you created way back at the beginning, but you don’t remember exactly what it was called. Here are some useful commands for working with variables in IPython.

who	show contents of workspace
who int	show integers in workspace
whos	show details of workspace contents
whos int	show details of integers in workspace
psearch msg*	search for objects in the workspace starting with msg
psearch msg* int	restrict search to just integers
reset	delete all variables from workspace

Getting help in IPython

ryan — Sun, 02 Dec 2007 17:04:08 +0000

IPython has an in-depth integrated help system. You can get help on IPython’s magic functions, view documentation from a single function, check out syntax-highlighted source code, or enter the Python interactive help system. Here’s a list of the commands to use.

lsmagic	lists the magic commands
?	(at the end of a function or variable) show help
??	(at the end of a function or object) show detailed help; often includes source code
help(sys)	online documentation for the sys module (sys must be imported first)
help(‘for’)	online doc for the for keyword
help()	enters the help system
topics	(at the help prompt) lists help topics. Type one to view it.
q	(at the help prompt) Exit the help system.

Import the re module (regular expression module) as an example for the commands below:

import re

pdef re.match	just the initialization expression for the re.match function
pdoc re.match	just the help text for re.match
pinfo re.match	same as using re.match? (shows help)
psource re.match	same as using re.match?? (shows detailed help)
pfile re.match	shows the contents of the file where the function is defined
pycat scriptName	displays the file, scriptName, in syntax-highlighted text
edit -x re.match	opens the source file for re.match in default editor