IPython Cheat Sheet

# Line magic (single %)
%pwd  # Print working directory
%ls   # List files
%cd /path/to/directory

# Cell magic (double %%)
%%time
sum(range(1000000))

# Run shell commands with !
!ls -la
!pwd
!python --version

# Capture output
files = !ls
print(files)

# Question mark for help
len?
str.split?

# Double question mark for source
len??

# dir() for attributes
dir(str)

# Type and press Tab
import numpy as np
np.ar<TAB>  # Shows array, arange, etc.

# Works with file paths
!cat ~/Doc<TAB>

# Find matching names
*Warning*?
str.*find*?

# Time single line
%timeit sum(range(1000))

# Time cell
%%timeit
total = 0
for i in range(1000):
    total += i

# Run Python file
%run script.py

# Run with profiler
%run -p script.py

# Run and debug on exception
%run -d script.py

# Load code from file
%load script.py

# Save cell to file
%%writefile output.py
def hello():
    print("Hello, World!")

# Show command history
%history

# Show last n commands
%history -n 10

# Save history to file
%save mycode.py 1-10

# List all variables
%who

# List with types
%whos

# List specific types
%who str
%who int

# Delete specific variable
del my_var

# Delete all variables
%reset

# Delete without confirmation
%reset -f

# Store to database
%store myvar

# Restore from database
%store -r myvar

# List stored
%store

# Automatic debug on exception
%pdb on

# Manual breakpoint
import pdb; pdb.set_trace()

# Or use IPython debugger
from IPython.core.debugger import set_trace
set_trace()

# In debugger:
# n - next line
# s - step into
# c - continue
# l - list code
# p var - print variable
# q - quit
# h - help

# Set environment variable
%env MY_VAR=value

# Get environment variable
%env MY_VAR

# List all env vars
%env

# Change directory
%cd /path/to/dir

# Go to home
%cd ~

# Go back
%cd -

# Create bookmark
%bookmark myproject /path/to/project

# Use bookmark
%cd myproject

# List bookmarks
%bookmark -l

# For Jupyter notebooks
%matplotlib inline

# For interactive plots
%matplotlib notebook

# For Qt backend
%matplotlib qt

import matplotlib.pyplot as plt
import numpy as np

%matplotlib inline

x = np.linspace(0, 10, 100)
y = np.sin(x)
plt.plot(x, y)
plt.show()

# Start recording
%macro mymacro 1-5

# Run macro
mymacro

# Edit macro
%edit mymacro

# Paste code and execute
%paste

# Paste without executing
%cpaste

# Access previous output
_ # Last output
__ # Second to last
___ # Third to last

# Access by line number
Out[5] # Output from cell 5
_5 # Same as above

# Start IPython cluster
!ipcluster start -n 4

# Use parallel magic
from ipyparallel import Client
rc = Client()
view = rc[:]