Dynamic Object Introspection

IPython can inspect any object at runtime: its type, its methods, its documentation, and its source code - no debugger required. Tab completion, question marks, and the built-in help machinery turn the prompt into an interactive explorer for unfamiliar libraries.

Question Marks

import numpy as np

np?              # quick doc: name, type, signature, short description
np.linalg?       # doc for a module
np.linalg.solve??  # double question mark: full docstring

Who Am I - %who, %whos

a = 1
df = "some frame"
%who
%whos          # adds type and size for each variable

%pinfo - Detailed Inspection

%pinfo np.linalg.solve
# shows: type, module, docstring, source file, calling signature

%get_ipython and Source

%pinfo -s np.array      # source of the object, if available
import inspect
print(inspect.signature(np.linalg.solve))

dir, help, and type

print([m for m in dir(np) if "sort" in m])
help(np.sort)
print(type(np.array([1, 2])))

A Workflow for New Libraries

import the package, then %whos to see what you have loaded.
package? for the overview docstring.
package.module? to drill into submodules.
function?? for the full docstring, including examples.
Tab completion to autocomplete attribute names as you type.

Summary

Use ? and ?? for instant documentation, %who/%whos to list your variables, %pinfo for detailed object inspection including source, and dir/help/type for the standard introspection tools. This interactive loop - import, explore, drill in - is how you learn any library without leaving the prompt.