Reading Manual Pages

It is almost sure that you will want to open manual pages for library functions. You can do it with the help of the help command.

In [1]: import numpy

In [2]: help(     
  numpy.arange       numpy.arcsinh      numpy.argmax       numpy.argwhere      
  numpy.arccos       numpy.arctan       numpy.argmin       numpy.around        
  numpy.arccosh      numpy.arctan2      numpy.argpartition numpy.array        >
  numpy.arcsin       numpy.arctanh      numpy.argsort      numpy.array2string

You just type part of the function then press Tab key to get a list of function.

You select the function you wish using the arrow keys then press Enter. Then you close the function call with a ) and press Enter.

Help on ufunc object:

arcsin = class ufunc(builtins.object)
 |  Functions that operate element by element on whole arrays.
 |  To see the documentation for a specific ufunc, use `info`.  For
 |  example, ````.  Because ufuncs are written in C
 |  (for speed) and linked into Python with NumPy's ufunc facility,
 |  Python's help() function finds this page whenever help() is called
 |  on a ufunc.
 |  A detailed explanation of ufuncs can be found in the docs for :ref:`ufuncs`.
 |  Calling ufuncs:
 |  ===============
 |  op(*x[, out], where=True, **kwargs)
 |  Apply `op` to the arguments `*x` elementwise, broadcasting the arguments.
 |  The broadcasting rules are:
 |  * Dimensions of length 1 may be prepended to either array.
 |  * Arrays may be repeated along dimensions of length 1.

You can exist the help screen using Shift+Q.

Another way of achieving the same result is to append a question mark at the end of the function then press Enter (will give you information from docstrings).

In [3]: numpy.arcsin?

The result is something like shown below:

Call signature:  numpy.arcsin(*args, **kwargs)
Type:            ufunc
String form:     
File:            ~/env/data_analysis/lib/python3.5/site-packages/numpy/
arcsin(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature, extobj])

Inverse sine, element-wise.

x : array_like
    `y`-coordinate on the unit circle.
out : ndarray, None, or tuple of ndarray and None, optional
    A location into which the result is stored. If provided, it must have
    a shape that the inputs broadcast to. If not provided or `None`,
    a freshly-allocated array is returned. A tuple (possible only as a
    keyword argument) must have length equal to the number of outputs.
where : array_like, optional
    Values of True indicate to calculate the ufunc at that position, values
    of False indicate to leave the value in the output alone.

In order to use Tab completion you have to have readline installed. You can install it using pip by running the following command in the terminal.

pip install readline

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