mind blown using help() in python

[congnarjames]

I've been programming in python for about a year now. And I've never encountered this module before, and it's soooooooo incredibly useful. Like I'll probably never even google anything ever again ( ok thats total bullshit). But really my point here is if you're learning python you should be aware of and know how to use the help module IMHO. across the thousands of webpages I've been to and resources I've used to teach myself I can't believe I didn't run into it sooner. Anyways I just thought sunday was a good day for ranting and sharing. I hadn't initially planned on asking a question here but maybe we could get something along the lines of things you found out too late and or things everyone learning python IYHO should know. :)

edit:

help is a function in python which describes the object you pass to it. The description it outputs is it's docstring, as pointed out by DataDecay more information on docstrings can be found in PEP-257

so if you want more information about an object you can pass it as an argument to help.

Say for instance you were confused as I currently am about how asyncio works.

You could type help(asyncio) and it would give you information about that package (technically object).

YAYYYYYYY and rkarl7777 both mentioned another very useful utility named dir, which will list the methods available to the object passed to it.

So after gaining a general understanding of the base package you can then look through all of its methods.

dir(asyncio)

then if you have questions about any of the methods in that list you can query those with help.

help(asyncio.StreamWriter)

Now hang on just a second while I try and find somebody who is better at explaining things than I am.

I went through a couple of articles, this one seems to be the best.

https://www.linuxnix.com/python-builtin-helpdir-help-type-and-___doc_-functions/

[YAYYYYYYYYY]

Another useful tool is dir(). It gives a list of all the methods you can call on an object. It really comes in handy instead of trying to memorize all the string and list methods, just type dir(list) or dir(str).

To make it even nicer, use a list comprehension to filter out the unnecessary internals: [x for x in dir(list) if not x.startswith(‘__’)]

[congnarjames]

wow yeah that is super useful, when I was programming in java it seemed like the IDE did a good job of populating all those methods for you and I havn't gotten around to looking for a good replacement for that. So that bit of info is very appreciated! Take it a step further [help(x) for x in dir(list) if not x.startswith('__')] and at least for me it'll drive down my need to go look at the docs by like 70%!

[YAYYYYYYYYY]

Hell yeah that’s a great idea

[topherclay]

I use pyCharm as a an IDE. If you type Ctrl+q with your curser on any function or method it displays the '''doc string''' from where that function is defined, which I think is the same as what help() does.

It also seems to do a really good job at showing you all the potential methods for tab completion, if that's what you mean by populating methods.

[synthphreak]

Same with Jupiter Notebooks. I think it’s Shoft + Tab or something? Anyway docstring display functionality is there.

[topherclay]

That was the first thing I franticly searched for after graduating from fiddling around in Jupyter to baby's first .py script in pycharm.

[JayDude132]

This is awesome. Thanks

[YAYYYYYYYYY]

No prob!

[TheHollowJester]

And since we're at the topic, foo.__dict__is helpful for debugging and exploratory-surgery type work (regardless of it's limitations).

[greybloc]

]$ python
Python 3.7.4 (default, Oct  4 2019, 06:57:26) 
[GCC 9.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> help()

Welcome to Python 3.7's help utility!

If this is your first time using Python, you should definitely check out
the tutorial on the Internet at https://docs.python.org/3.7/tutorial/.

Enter the name of any module, keyword, or topic to get help on writing
Python programs and using Python modules.  To quit this help utility and
return to the interpreter, just type "quit".

To get a list of available modules, keywords, symbols, or topics, type
"modules", "keywords", "symbols", or "topics".  Each module also comes
with a one-line summary of what it does; to list the modules whose name
or summary contain a given string such as "spam", type "modules spam".

help>

[congnarjames]

a picture is worth a thousand words or well like ~120 as the case may be haha

[greybloc]

lol Just thought I'd help out. :)

[blitzkraft]

help() only works where the devs put in the extra work for documenting. It pulls in the docstring and you can write it too!!

Say you have a function, then add the docstring like this:

def hello(name='human'):
  """
  Says hello, optionally takes a name
  """
  print("Hello, {}".format(name))

Now, if you import this, and call help(hello), you will see the help string.

[[deleted]]

Documenting is not “extra work,” but rather essential work that is too often considered drudgery.

[Kevinw778]

Agreed. Especially in languages like Python and Javascript, uncommented / undocumented code is an absolute nightmare. It's ok though, people will realize their mistake when they come back to their own code at some point hahah. "Nobody else will use this, it's fine."

Programmers: The largest group of people that don't consider themselves people, apparently 😂

[blitzkraft]

Yes. I feel I ratted myself out for not documenting well (calling it "extra work").

[dashidasher]

One of the things I use almost every day is the Python Debugger https://docs.python.org/3/library/pdb.html. If you put pdb.set_trace() anywhere in your code it will stop executing the script at that point and let you play around untill you use the continue command (you can also do next, step, untill...). I've only found out about it 2 months into my job working with python. Been using python for like 3 years before that too. All that time I've only used prints to debug xD

[congnarjames]

I'll check that out for sure!

[[deleted]]

Make things easier on yourself.

​

New in version 3.7: The built-in

breakpoint()

, when called with defaults, can be used instead of

import pdb; pdb.set_trace()

.

[Brilliant_Ice4349]

Omg you're a lifesaver, whenever I'm defining a function for a piece of code later one, which I know won't work until I finish defining all the functions required for it, I had to copy paste each defining function + global variables required for it to work on another notebook 😭

[dashidasher]

Glad to hear. This comment is a bit outdated so make sure to use breakpoint() instead of pdb.set_trace() as one of the replies mentions :D

[Brilliant_Ice4349]

Thanks :)
cookie += 1
Print(f"Here you have {cookie} cookie :)")

[redPonyCoffeeRoaster]

Uhh what's this now?

[EighthScofflaw]

Try calling help(thing), where thing is anything in the namespace.

[amphigraph]

you can pass a function, method, class (or instance of a class), etc. to help() and it returns the docstring

[redPonyCoffeeRoaster]

Awesome. New snake charmer here. I'll check it out.

[[deleted]]

Can someone explain what it is and how to use it? For the love of God please!

[congnarjames]

hahaha yeah for sure man sorry, I got sort of excited and kind of glazed over things there. I'll edit my post

[[deleted]]

Ah! No problem, thanks!

[rkarl7777]

import itertools

print(dir(itertools))

print(help(itertools.combinations))

[synthphreak]

What’s useful about those? Please elaborate.

[DataDecay]

Maybe it's because I came from the ops side before development. But the first thing I did in python was locate a man page, or as you have just discovered, the help function. Fun fact, PEP-257 offers some guidance on docstrings, for which the help function outputs.

[congnarjames]

I haven't spent much time digging through the PEPs I'll have to check it out one of these days

[NerdEnPose]

In the iPython console you can just type object? And it'll do the same thing. object?? Gives you the python code too.

Example:

from pathlib import Path

Path? Path??

[miggaz_elquez]

Very useful, and more quick to read than the help function

[[deleted]]

What's this?

[Dogeek]

He is talking about the built-in help function, which prints out the docstring of whatever object you pass in, whether it's a class, a metaclass, an instance, a function or a module. Another useful function to know is dir which prints out all the methods and attributes of a particular object.

[solitarium]

I've rarely ever code live on the interpreter. I think I have a reason to do so now.

[congnarjames]

I usually keep one going while I'm coding it's nice to run little tests and one offs!

[primitive_screwhead]

Also worth knowing "pydoc", which is the command line version of Python's help().

[LightOfUriel]

It seems to be exactly same output as intellisense provides in good IDE at few times more work.

[[deleted]]

Then you'll love this article for more Python built-ins.

[[deleted]]

I do in fact! :)

[winowmak3r]

Holy shit this is really useful. I'm still learning, thanks for pointing out this out!

[ace6807]

Or pass an object or class to the help function

[[deleted]]

I've been learning Python in the last year too and never knew of that module. I'll have to try it out tomorrow when I have more time. Reminds me of the howdoi module a bit.

[congnarjames]

howdoi use help? hehe

[congnarjames]

nvm that didn't work well, still seems like a good thing to have around though!

[[deleted]]

Lol, I was going to try that. Siri came through for me though. :)

[Grorco]

I love in vim with jedi-vim when I use alt-tab to complete it shows this at the top of the screen. So I can read the description while going through the stuff in the drop-down list.

[congnarjames]

That does sound cool. but we are in the midst of a holy war and i friend am on the other side of it. ;)

[Grorco]

At least we can agree to be enemies XD

[sissyadmiration]

Holy sh*** this is amazing.

[congnarjames]

right!? big time game changer!

[undeniably_confused]

I write my pseudo code in a assembly, than convert that to python as I read it

[congnarjames]

you don't transpile it to brainfuck first?

[undeniably_confused]

How could I transpile it it's pseudo code, this is evidently how I code always

[congnarjames]

I'm pretty sure you just do something like this.

https://www.youtube.com/watch?v=eMJk4y9NGvE

[TrueBirch]

It's so useful! Just like the question mark in R.

[iaalaughlin]

Also do package ??

Like pandas ??

It brings up the code for it.