1 00:00:05,350 --> 00:00:09,700 Welcome back everyone in this lecture we're now finally going to discuss how to write your own modules 2 00:00:09,730 --> 00:00:11,580 and packages. 3 00:00:11,810 --> 00:00:15,800 So we understand how to install external packages that people uploaded to pie pie. 4 00:00:15,920 --> 00:00:20,940 Let's explore how to create own modules and packages and to clarify some of the semantics here. 5 00:00:20,970 --> 00:00:23,510 Module's it's really just a PI script. 6 00:00:23,690 --> 00:00:28,850 So it's a fancy way of saying here's a postscript that I'm using in another PI script. 7 00:00:28,850 --> 00:00:33,550 So that act of using it in another PI script allows you to call it a module. 8 00:00:33,560 --> 00:00:38,120 Again this is really just semantics but packages are then a collection of modules. 9 00:00:38,120 --> 00:00:42,830 However there's a key that postscript called underscore underscore in its underscore underscored the 10 00:00:42,860 --> 00:00:48,830 pie that needs to be placed inside of a folder to let Python know that this collection of that postscripts 11 00:00:48,890 --> 00:00:51,510 should be treated as an entire package. 12 00:00:51,530 --> 00:00:54,180 So we're going to show all of this through some examples. 13 00:00:54,200 --> 00:00:58,250 Keep in mind since we're dealing with postscripts here we're not going to be able to show these examples 14 00:00:58,310 --> 00:00:59,300 through the notebook. 15 00:00:59,300 --> 00:01:05,950 Instead we're going to need to do is use subline text editor or any other idea that works without PI 16 00:01:05,960 --> 00:01:09,250 files in order to create the scripts and folders. 17 00:01:09,260 --> 00:01:12,560 Let's get started by opening up Sublime Text Editor. 18 00:01:12,560 --> 00:01:16,220 All right so we're going to start off by creating two files here. 19 00:01:16,280 --> 00:01:22,880 The first one will save it to the desktop will say file new file or we can actually save the don't currently 20 00:01:22,880 --> 00:01:30,610 have save as and on my desktop I'm going to say this as my module not pi. 21 00:01:30,680 --> 00:01:35,900 So this is the module and remember all that module is just the top high script being called in from 22 00:01:35,900 --> 00:01:37,030 another file. 23 00:01:37,460 --> 00:01:42,060 So let's create the other file saying you file and this one we're going to save it. 24 00:01:42,140 --> 00:01:48,860 Also on the desktop in the same location as my module that pie and I will say my program that pi and 25 00:01:48,920 --> 00:01:49,930 save that. 26 00:01:50,320 --> 00:01:56,600 So inside of my module what I'm going to do is just create a very simple function will say F and then 27 00:01:56,600 --> 00:02:09,690 say my func and all this does is it prints out hey I am in my module PI control s to save that. 28 00:02:10,100 --> 00:02:15,510 And then in my program this is another dot PI script and I want to use the code from my module. 29 00:02:15,680 --> 00:02:19,790 So here we can get the idea that if you have a really large script you're not going to put everything 30 00:02:19,790 --> 00:02:21,460 in one giant pie file. 31 00:02:21,470 --> 00:02:27,050 Instead it will be nice to split it up between multiple dot py files which means you split up between 32 00:02:27,050 --> 00:02:31,370 different modules and then later we'll see how he can aggregate bunch of modules to create a package 33 00:02:32,150 --> 00:02:42,800 so far or do in my program say from my module import and then we're going to import my funk and let 34 00:02:42,800 --> 00:02:44,000 me make sure I spell that right. 35 00:02:44,000 --> 00:02:44,230 OK. 36 00:02:44,240 --> 00:02:46,840 My underscore phunk. 37 00:02:47,080 --> 00:02:49,630 And that means I can now call it here. 38 00:02:49,690 --> 00:02:52,710 So I'll say my phunk I'm going to say this. 39 00:02:52,750 --> 00:02:55,510 And let's see if it works by going to our command line. 40 00:02:55,510 --> 00:02:57,140 So here I am now at my command line. 41 00:02:57,160 --> 00:02:59,530 Remember I save these files at my desktop. 42 00:02:59,530 --> 00:03:02,730 So let's see the to the desktop change directory. 43 00:03:03,020 --> 00:03:10,330 And now I should be able to call Python and then call my program that PI enter and I see hey I and my 44 00:03:10,330 --> 00:03:11,620 module pi. 45 00:03:11,830 --> 00:03:17,920 So we were able to successfully call the other function from the other module the py file into my program 46 00:03:17,920 --> 00:03:24,310 that pi and this is the very basic way of how you would actually format the PI scripts in order to not 47 00:03:24,310 --> 00:03:26,740 have everything in a single script. 48 00:03:26,740 --> 00:03:31,510 Now at a certain point even this is going to start to be too much and now you're going to want to aggregate 49 00:03:31,900 --> 00:03:36,940 modules together to form and package and that way you can have different folders for different packages. 50 00:03:36,940 --> 00:03:40,550 So let's show you how to create a package's. 51 00:03:40,690 --> 00:03:47,110 So we're going to come back here to my program that pi in my module top pie and will open up and say 52 00:03:47,170 --> 00:03:54,970 new file and then we're going to save this Save As and here at my desktop I'm going to do a few things. 53 00:03:56,330 --> 00:03:59,540 The first thing I'm going to do is create a new folder here. 54 00:04:01,020 --> 00:04:06,410 And this folder will call it my main packet. 55 00:04:08,480 --> 00:04:15,670 Enter And then inside of this folder we're going to create another new folder and we'll call this sub 56 00:04:15,670 --> 00:04:16,590 package. 57 00:04:16,870 --> 00:04:20,040 So we're going to be creating lots of files and folders here. 58 00:04:20,140 --> 00:04:26,110 So right now we have at my desktop my module up high in my program that pi and I've also created my 59 00:04:26,110 --> 00:04:30,500 main package folder and inside of that I have my sub package. 60 00:04:30,580 --> 00:04:35,110 Now since these are just directories or folders we need to let Python be able to understand that we 61 00:04:35,110 --> 00:04:39,660 want to treat these directories not just as a normal directory but as an actual package. 62 00:04:39,700 --> 00:04:47,250 So to do that inside both my main package and sub package I'm going to have to create a file called 63 00:04:47,310 --> 00:04:50,030 underscore underscore in it. 64 00:04:50,090 --> 00:04:58,770 I NIIT underscore underscore that PI save that and make sure you have this in it py file in your package 65 00:04:59,430 --> 00:05:02,250 now you don't actually need to write anything in this file. 66 00:05:02,280 --> 00:05:07,080 It just needs to be there so that when Python goes searching through these packages it understands that 67 00:05:07,080 --> 00:05:09,960 it's not just the normal directory it's an actual package. 68 00:05:09,990 --> 00:05:13,530 So we're going to create one more files a new file. 69 00:05:13,710 --> 00:05:21,120 Now we're going to say this under some package will create another underscore underscore in it underscore 70 00:05:21,120 --> 00:05:23,400 underscore the PI file. 71 00:05:23,400 --> 00:05:25,600 And again this one is going to be blank as well. 72 00:05:26,440 --> 00:05:28,390 So we have both of these. 73 00:05:28,390 --> 00:05:32,740 Notice here how sublime is telling us which are referring to this one in my main package and this one 74 00:05:32,740 --> 00:05:33,650 in the package. 75 00:05:33,670 --> 00:05:34,600 So we're going to close these. 76 00:05:34,600 --> 00:05:36,320 We're not going to be working with them anymore. 77 00:05:36,490 --> 00:05:38,900 We just need to have them name there. 78 00:05:39,390 --> 00:05:39,860 OK. 79 00:05:39,880 --> 00:05:51,860 So I had my module and my program what I'm going to do now is say file new file and I will say save 80 00:05:51,860 --> 00:06:05,710 as an inside of my main package and I'm going to create some main script that PI save that and then 81 00:06:05,750 --> 00:06:08,350 we'll also do a file new file. 82 00:06:08,610 --> 00:06:11,940 And let's put another PI script inside of my sub package. 83 00:06:12,130 --> 00:06:21,230 So we will save file save as an inside of the sub package along that other file We're going to create 84 00:06:21,230 --> 00:06:28,380 the following we will say my sub script that pi. 85 00:06:28,390 --> 00:06:34,720 So now I have this outside module some main script inside of that main package folder. 86 00:06:34,900 --> 00:06:41,800 This subscript inside of that sub package folder and then my main program so we can do is we can start 87 00:06:41,800 --> 00:06:44,860 playing around with this all the way for my program. 88 00:06:44,860 --> 00:06:54,150 So what I'm going to do is inside of my subscript will say if than say sub report and have that print 89 00:06:54,150 --> 00:06:54,860 out. 90 00:06:55,210 --> 00:07:02,490 Hey I'm function inside my subscript 91 00:07:06,190 --> 00:07:11,360 control as the save that we're going to do a very similar thing here in some main script and we will 92 00:07:11,360 --> 00:07:16,240 say the E-F will call this report main 93 00:07:19,000 --> 00:07:20,360 and this will print out. 94 00:07:20,960 --> 00:07:33,270 Hey I am in some main script in main pack which say that it's well OK. 95 00:07:33,330 --> 00:07:35,700 So let's take a look at the rectory right now. 96 00:07:35,850 --> 00:07:38,820 We'll say open a file just so we can explore this. 97 00:07:38,850 --> 00:07:43,860 So at my desktop right now I have this my module that PI won't really be playing with that anymore but 98 00:07:43,860 --> 00:07:46,160 instead I have this my program that pi. 99 00:07:46,320 --> 00:07:49,350 Now we can think of my program that pi as the main PI script. 100 00:07:49,380 --> 00:07:53,490 I want to run and I want to organize my files into packages. 101 00:07:53,580 --> 00:07:58,380 So right now we've explored how to actually create a single module which is just the PI script and you 102 00:07:58,380 --> 00:08:03,810 can imagine we'd be importing from various modules so various scripts that at a certain point it's going 103 00:08:03,810 --> 00:08:06,370 to be too much and we want to organize them into folders. 104 00:08:06,410 --> 00:08:11,600 So the way you would do that is you would have packages which are just directories that have this in 105 00:08:11,930 --> 00:08:12,480 the pie. 106 00:08:12,480 --> 00:08:15,270 So underscore underscore in an underscore underscore that pie. 107 00:08:15,410 --> 00:08:20,040 And that tells Python hey this actual directory it has a bunch of modules in it so you can call them 108 00:08:20,370 --> 00:08:22,950 using a certain syntax which we're about to show you. 109 00:08:23,370 --> 00:08:24,810 So here we have some main script. 110 00:08:24,930 --> 00:08:30,930 You can imagine I could have many more postscripts or many more modules inside of this package and we 111 00:08:30,930 --> 00:08:34,850 can keep going with sub packages as long as they have this in that pie. 112 00:08:34,870 --> 00:08:36,950 And here I can see my subscript. 113 00:08:37,260 --> 00:08:43,290 So I'm going to cancel this and when I'm going to do is inside my program that pi I already know how 114 00:08:43,290 --> 00:08:44,410 to import from module. 115 00:08:44,420 --> 00:08:50,940 But now let's realize how to import from a package to import from a package what I can say is from my 116 00:08:51,090 --> 00:08:53,910 main package. 117 00:08:54,270 --> 00:08:57,350 I can either import the actual module itself. 118 00:08:57,510 --> 00:09:01,790 Remember the module in my main package it was called some main script. 119 00:09:02,180 --> 00:09:12,020 So we'll save some main script and if I wanted to import from a sub package what I would say from my 120 00:09:12,020 --> 00:09:19,800 main package dot sub package and then I can import some module from there. 121 00:09:19,810 --> 00:09:25,720 So in this case it was called My subscript. 122 00:09:25,830 --> 00:09:31,950 So this is now how you can organize not just into a single directory but you can actually organize into 123 00:09:31,950 --> 00:09:33,310 subdirectories as well. 124 00:09:33,330 --> 00:09:38,220 And this is the syntax for that you say dot the name of that sub package import and then import the 125 00:09:38,220 --> 00:09:38,970 modules. 126 00:09:39,060 --> 00:09:43,500 And if you want you can go even further and actually import only specific functions. 127 00:09:44,900 --> 00:09:46,660 So we'll show you how to do that in just a second. 128 00:09:46,670 --> 00:09:50,200 But let's actually call the functions from some main script. 129 00:09:50,300 --> 00:09:56,030 So from some main script right here we want to call the function that's inside that script so if we 130 00:09:56,030 --> 00:10:01,950 click back here we realized that that one is just called Report main. 131 00:10:01,970 --> 00:10:07,750 So coming back or I'll say some main scrip report main close parentheses. 132 00:10:07,790 --> 00:10:12,530 So we're actually executing the function report Main which is under some main script module which is 133 00:10:12,560 --> 00:10:14,280 under my main package. 134 00:10:14,300 --> 00:10:18,480 Then we also want to if we look at my subscript that has the subreport. 135 00:10:18,620 --> 00:10:27,360 So let's run that as well saying my subscript call sub report open close princes. 136 00:10:27,600 --> 00:10:31,810 So let's save that and then let's run my program that pi at the command line. 137 00:10:32,040 --> 00:10:33,600 So we can see what happens. 138 00:10:33,600 --> 00:10:39,300 All right so now here back on my desk top up the command line I will say Python call my program that 139 00:10:39,300 --> 00:10:46,230 pi and I hit enter and I see hey I am some main script in main package and then hey I'm a function inside 140 00:10:46,230 --> 00:10:48,090 my subscript and that's it. 141 00:10:48,090 --> 00:10:52,770 Now you've successfully not only created a module in the first produce lecture but you also created 142 00:10:52,770 --> 00:10:55,010 packages and sub packages. 143 00:10:55,110 --> 00:11:00,660 And in general the idea here is just how do you organize various Paice scripts as you begin to grow 144 00:11:00,660 --> 00:11:01,810 better and better in Python. 145 00:11:01,860 --> 00:11:04,210 You're going to write more and more Python code. 146 00:11:04,320 --> 00:11:07,840 So at the beginning you'll create a couple of modules to all be in the same folder. 147 00:11:07,860 --> 00:11:13,710 No big deal then as it starts getting more and more unwieldy to have it all in the same folder all you 148 00:11:13,710 --> 00:11:18,660 need to do is create directories to have that special underscore underscore in it underscore underscore 149 00:11:18,720 --> 00:11:19,780 that py file. 150 00:11:19,860 --> 00:11:24,730 That just tells Python hey this is now a package and it allows you to run. 151 00:11:25,140 --> 00:11:25,980 What we see here. 152 00:11:26,040 --> 00:11:28,190 This my main package my main. 153 00:11:28,200 --> 00:11:29,820 That's a package. 154 00:11:29,820 --> 00:11:35,460 Notice here we were actually importing modules so you can see here that I'm just saying from some package 155 00:11:35,460 --> 00:11:40,980 name import some module what you could do as well is import functions. 156 00:11:40,980 --> 00:11:46,980 If you only intend to to use a single function so you could say from my main package import some main 157 00:11:46,980 --> 00:11:47,780 script instead. 158 00:11:47,820 --> 00:11:58,700 You could do say from my main package dot some main script import report main Whoops no open close friends 159 00:11:58,740 --> 00:12:04,330 there and then instead of calling some main script you would just say report name. 160 00:12:04,410 --> 00:12:10,010 So that's the same thing and we can come back and confirm that at our command line coming back here. 161 00:12:10,300 --> 00:12:11,860 We run this again and we see. 162 00:12:11,880 --> 00:12:13,900 Hi I am some script again. 163 00:12:14,110 --> 00:12:18,560 It's up to you whether you want to import entire modules or just specific functions. 164 00:12:19,000 --> 00:12:19,480 OK. 165 00:12:19,660 --> 00:12:24,460 That's the basic idea of packages and modules if you have any questions feel free to post to community 166 00:12:24,460 --> 00:12:27,170 forums and we'll be happy to help you out there. 167 00:12:27,190 --> 00:12:28,150 I'll see you at the next lecture.