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Forum Index : Microcontroller and PC projects : Python....
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9593 |
I am about to start having a play around with Python on the Raspberry Pi 2, and wondered if we have any members here who are adept at programming in Python, who will be able to help me if I post questions on this language? I know there are plenty of web resources, but TBS is much closer to home. Was not MMEDIT written in Python?(compiled for Windoze) Smoke makes things work. When the smoke gets out, it stops! |
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| mindrobots Newbie  Joined: 21/05/2014 Location: United StatesPosts: 32 |
I've dabbled in Python and written a few small things. I wander away and need to refresh my brain as to how it differs from the last thing I used. I do like it and do keep coming back to it. I'm sure your knowledge will shortly surpass mine but I'd be happy to field questions - teaching is the best way to learn something!! 
Rick EDIT: The 12 hour time delay may give me time to research your questions and look smarter than I really am!!  |
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TassyJim Guru  Joined: 07/08/2011 Location: AustraliaPosts: 6269 |
No. MMEdit is written in Liberty Basic and the next version will be written in PureBasic. The first thing you will notice with Python is the indenting - it has to be right. I know sod all about Python so wont be much help. There are good resources on the PI forum and MagPi has well written articles. http://www.raspberrypi.org/magpi/ Jim VK7JH MMedit |
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| cwilt Senior Member  Joined: 20/03/2012 Location: United StatesPosts: 147 |
I don't claim to be an expert but will help when I can. My python knowledge is not on rpi, but pcduino. |
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| hitsware Guru Joined: 23/11/2012 Location: United StatesPosts: 535 |
How about Python version of PRINT "hello world" |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9593 |
Thanks for the replies, fellas, and to Jim for clarifying that MMEDIT was NOT written in Python - not sure where that came from..... Anyhoo.... Once my Pi2 arrives, I will have a play. There are lots of videos on YouTube etc, of Python programming examples, so I will try all this stuff first, but was interested to know if any members here program in Python, so I could put up questions if I had any. Smoke makes things work. When the smoke gets out, it stops! |
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mbramwel Regular Member  Joined: 10/07/2013 Location: CanadaPosts: 42 |
I have coded in many languages including php under Linux. I was using php for command line apps/utilities. php is not just for web pages (which is what most people claim when you say php). I wanted to learn python so I could port my php programs to python. I thought it can't be that difficult, they are using the rPi to teach python to kids. I signed up on the free site: http://www.codecademy.com/ It took about 2 weeks of evenings to go through the lessons. I thought the site did a good job. It works by showing you a small example of how something works and asks you to create a small 1 to 5 line python script to use that new function. It then runs it and determines if you got it right. If you post command line stuff, I can help. I am not interested in GUI or Graphics in python. My only real complaint about python is the spacing/indentation. Many languages use a symbol to signal start/end of a block. Python uses indentation and complains if you get it wrong. There is LOTS of code libraries for python to do just about anything. I recommend learning python if you have not already done so. I have ported some of my apps from php to python. Generally speaking, my python versions run much faster than php. Many of my programs are reading large arrays and performing calculations & lookups. Python has fast methods of searching through arrays. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9593 |
Thanks for your post, and the link to codecademy. I will sign up there. Smoke makes things work. When the smoke gets out, it stops! |
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| cwilt Senior Member Joined: 20/03/2012 Location: United StatesPosts: 147 |
Your a natural. 
Put that line in a file named hello.py and then execute python hello.py |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2437 |
those who are interested might like to have a look here: http://www.brython.info/tests/console.html?lang=en this is an online python 3 implementation (BRowser pYTHON) that is pretty neat for doing quick-and-dirty testing of small bits of code. it is quite cut down, and runs within your browser using some clever java script. you should bear in mind that there are two branches of python: the 'classic' 2.7 and the current 3.x branch. the language did a bit of a split when version 3 came out, as 3.x versions are not completely backwards compatible in their syntax. the 2.7 branch is likely to stay around indefinitely with occasional maintenance releases, and some folks do seem to prefer it. i like 2.7, but would (reluctantly) have to recommend 3.x for newcomers. regarding the lack of block markers - in my opinion that is the one major failing of the language. i live in hope that when a version 4 appears the developers may see sense and introduce begin ... end markers, doing away with all this silly use of white-space as part of the code. cheers, rob :-) |
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| hitsware Guru Joined: 23/11/2012 Location: United StatesPosts: 535 |
Geez ..... Then Python's just the same as Basic  |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9593 |
Why? Is 3.x easier to learn then 2.7? Smoke makes things work. When the smoke gets out, it stops! |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2437 |
i'd not say any easier to learn, but as 2.7 ages support on new platforms is likely to trail off. 10 years from now, if you sit down at a python console, it is far more likely to be version 3.x or later. as an example, on 2.7 the following works: >>> print "hello world"
while on 3.1 the syntax required is: >>> print ("hello world")
if you leave out the brackets, it will not work on 3.x and throw up an error message. this caught me out first time i tried using brython. the 3.x branch seems to aim to force stricter formatting (with brackets) of all function calls, bringing it more in line with C syntax. i'm not a python expert, others may be able to better comment on the differences. cheers, rob :-) |
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G8JCF Guru Joined: 15/05/2014 Location: United KingdomPosts: 676 |
I hate the indent syntax !! The only Konstant is Change |
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| cwilt Senior Member Joined: 20/03/2012 Location: United StatesPosts: 147 |
Rob is correct. If you have the choice you should learn 3.+. There is a passing of the baton now and support is split between the two. I still run into cases where a module has not been converted to 3. The whitespace keeps you on your toes. Seriously, even the most basic text editor that handles python should auto indent for you, but you still must pay attention.
I am resisting the move away from 2.7, but it is inevitable. Resistance is futile. |
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| mbramwel Regular Member Joined: 10/07/2013 Location: CanadaPosts: 42 |
Personally, I learned 2.x a few months ago. I like it a lot. There are *small* differences between 2.x and 3.x Very small differences. For me, the fact that 2.x seemed to have the best libraries and 3rd party support with 3.x being planned (eventually) made me pick 2.x. I agree that 2.x probably will cease to exist in 10 years. But 10 years is a LONG time in computer-land. oddly enough, it is the print command that will probably be the item that hits you with 2.x to 3.x I have some php to python notes, I'll post in a new message |
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| mbramwel Regular Member Joined: 10/07/2013 Location: CanadaPosts: 42 |
When I started to look at python, I quickly felt it was just like all the other languages. The syntax was so close to php, maybe I could do a simple search/replace and quickly convert the php code to python. example: php mystring = "hello " . "world"; python mystring = "hello " + "world" as a test, I did a search replace of " . " to " + " I also dropped all trailing ; A few other hints were compiled and I posted them here: www.foxhollow.ca/php2python To speed up my php to python app conversion, I cheated. Python allows us to make 1 line functions that look like the php command. Example: My php used the trim function python has something that does the same thing so I made a simple function with the php name but uses the python command... def trim(mystring): return mystring.strip() Everywhere in my php script that used the trim command, now works aok in the python script. By seeding a few functions at the top of my php script, plus some search/replace, I converted many of my php programs to python in minutes. another example of a python function to emulate php function: # ************************************************************ # PHP: strpos() # ************************************************************ def strpos(haystack, needle): return (needle in haystack) Granted I am talking about php -> python here, not basic -> python, but I hope I am giving you some ideas on how to do things. We could also come up with a bunch of basic-to-python functions so conversion of apps would be super easy. note: line numbers and "goto" will be tough "gosub xxx" is easy because all python functions are basically the same thing as a gosub, the difference is "gosub name" is now just "name" |
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| mbramwel Regular Member Joined: 10/07/2013 Location: CanadaPosts: 42 |
A comment about python2 versus python3, especially the print command. I decided in the first few days to not use print unless I really needed it. 2 reasons: [1] it is different in python2 & python3 [2] it always prints a carriage return & line feed. In basic, we could do this: print "hello "; print "world" The above would display "hello world" (without the quotes of course) In python, we cannot end with the ";" Instead of print, I use the sys function. root@web1:/opt/markware/python# cat helloworld.py import sys sys.stdout.write("Hello ") sys.stdout.write("World\n"); root@web1:/opt/markware/python# python2 helloworld.py Hello World root@web1:/opt/markware/python# python3 helloworld.py Hello World root@web1:/opt/markware/python# Note that the above code works aok in both python2 and python3 |
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| Dylan Regular Member Joined: 17/06/2013 Location: NetherlandsPosts: 81 |
In Python 2, ending a print statement with a comma "," will insert a space. Handy for debugging! So print "hello",
print "world" print 42 will output hello world
42 I have not yet used Python 3 in anger. The main reason for this is risking not being able to use a library. That said, I dabble. |
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| mindrobots Newbie Joined: 21/05/2014 Location: United StatesPosts: 32 |
In Python3: print("Hello",end=" ") # append space instead of newline print("world!") print(42) will give you the same results as the Python2 example. with end=, you can override the way Python terminates a line. "\n" is the default. print became a real function in Python3 in Python2 is was kind of like a statement/keyword/function - that explains the need for () and also how it behaves differently. Google and StackOverflow are your friends! 
I almost know enough to be dangerous. Rick |
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