1 00:00:00,360 --> 00:00:05,640 Welcome to lesson 34 I have a folder on my hard drive called Delicious. 2 00:00:05,640 --> 00:00:07,980 It's right here in the root folder. 3 00:00:08,310 --> 00:00:10,750 And delicious has some more content inside of it. 4 00:00:10,740 --> 00:00:17,910 It has other folders and files like this foo folder or walnut folder has a file named spam txt and another 5 00:00:17,910 --> 00:00:20,870 one called Spam Spam Spam dirty XTi. 6 00:00:21,000 --> 00:00:28,200 If we go into that walnut folder and see it also has a folder and has an exe that text the file and 7 00:00:28,380 --> 00:00:34,680 inside that Waffles folder or some other files say I went to write some code that would apply to all 8 00:00:34,680 --> 00:00:38,970 of the folders and files inside of this delicious folder. 9 00:00:39,270 --> 00:00:47,010 Basically what I want to do is walk through this folder tree and either rename or copy or do something 10 00:00:47,010 --> 00:00:49,580 with all of these files in that code. 11 00:00:49,980 --> 00:00:52,250 Reading a program to do this could get tricky. 12 00:00:52,260 --> 00:00:58,500 But fortunately Python provides a function to handle this process for you. 13 00:00:58,500 --> 00:01:01,470 It's called the OS walk function. 14 00:01:01,470 --> 00:01:10,560 So first let's import the os module and Os up walk in past a root folder that you want to check. 15 00:01:10,560 --> 00:01:16,680 So in this case I want to look at the delicious folder and all the folders and files underneath it. 16 00:01:16,680 --> 00:01:21,270 Now the return value for this is used in four loops. 17 00:01:21,270 --> 00:01:26,340 I'll just say for right there and it actually instead of just returning one value like what the range 18 00:01:26,340 --> 00:01:30,390 function does so sort of having something like for I in range. 19 00:01:30,480 --> 00:01:35,130 It actually returns three values on each iteration of this loop. 20 00:01:35,220 --> 00:01:36,880 So the three values you can. 21 00:01:36,930 --> 00:01:40,100 This is just a regular for loop so you can name the variables whatever you want. 22 00:01:40,110 --> 00:01:42,310 But I like to go with these names. 23 00:01:42,370 --> 00:01:48,540 The first one I call folder name because the first of the three values will be a string with the folder 24 00:01:48,540 --> 00:01:49,890 name that it's currently looking at. 25 00:01:49,890 --> 00:01:57,210 On this iteration and then it also provides a list of all the folders inside that folder so I'm just 26 00:01:57,210 --> 00:02:03,210 going to say the variable subfolder can contain that list that also contains a list of strings for all 27 00:02:03,210 --> 00:02:07,560 the files inside this folder. 28 00:02:07,560 --> 00:02:11,840 This is kind of like what the OS does list during function returns. 29 00:02:11,850 --> 00:02:18,090 It's a list of file names so I can create this for loop and I'll just have a colon right here and on 30 00:02:18,120 --> 00:02:23,940 each iteration of this loop it'll go through all the folders underneath this delicious folder and on 31 00:02:23,940 --> 00:02:28,770 each iteration it also provides all the folders that are in that folder and all the files that are in 32 00:02:28,770 --> 00:02:30,150 that folder. 33 00:02:30,150 --> 00:02:34,460 So let me just write up some code just to that you can see what exactly is happening here. 34 00:02:34,470 --> 00:02:38,580 You have a lot of print functions here just to display all this data. 35 00:02:38,610 --> 00:02:45,020 I'm going to say the folder is and will just append the folder name. 36 00:02:45,330 --> 00:02:50,380 So on this iteration this or just print out whatever the folder it's currently looking at is and then 37 00:02:50,580 --> 00:03:06,090 also sub folders is a list so I could just say print the sub folders in folder name are and then I'll 38 00:03:06,090 --> 00:03:14,730 just print out this list value to convert that to a string first so that we can concatenate it and we 39 00:03:14,730 --> 00:03:21,080 can do the same thing here with the file names list. 40 00:03:21,120 --> 00:03:25,660 That's also a list others say and the file names inside that folder name are this. 41 00:03:25,860 --> 00:03:30,390 And then just have a blank print call just to print out a new life. 42 00:03:30,420 --> 00:03:36,590 You know when I press Enter this is going to walk through the entire for the entire directory tree or 43 00:03:36,600 --> 00:03:38,430 folder tree underneath. 44 00:03:38,430 --> 00:03:40,130 Delicious. 45 00:03:41,610 --> 00:03:44,550 So here's the output from this for loop. 46 00:03:44,550 --> 00:03:50,100 So here's the first iteration on that iteration is just looking at the delicious folder itself. 47 00:03:50,100 --> 00:03:58,020 And it's also so folder name has been set to see slash delicious and the subfolder list is a list of 48 00:03:58,020 --> 00:04:06,330 all the folder names inside that folder and file names is a list of all the files inside that folder 49 00:04:06,330 --> 00:04:06,720 . 50 00:04:06,720 --> 00:04:10,170 But then here's the great thing on the next iteration of this. 51 00:04:10,200 --> 00:04:11,720 Oh estopped walk. 52 00:04:11,760 --> 00:04:15,880 We're going to examine all of the folders underneath this delicious folder. 53 00:04:15,990 --> 00:04:21,660 So first we're going to take a look at delicious flesh food and I'll tell us all the folders and file 54 00:04:21,660 --> 00:04:26,940 names there and then I'll take a look at delicious slash walnut and I'll tell us all the folders and 55 00:04:26,940 --> 00:04:33,440 file names in that folder and then I'll keep diving deeper and deeper. 56 00:04:33,480 --> 00:04:40,140 Mel looking at delicious lush walnut slash waffles and I'll tell us all the folders and file names there 57 00:04:40,150 --> 00:04:41,070 . 58 00:04:41,600 --> 00:04:48,610 So I'm just going to copy this out and create a new file editor. 59 00:04:48,830 --> 00:04:50,060 We have code like this. 60 00:04:50,220 --> 00:04:56,640 So in each iteration it's easy to add code that would loop over this list of folder names we'd just 61 00:04:56,640 --> 00:05:01,510 say for subfolder in the folders. 62 00:05:01,660 --> 00:05:06,600 Or we could print out the subfolder name or we could do whatever we need to do with it. 63 00:05:06,600 --> 00:05:13,350 We could have code that say deletes this subfolder we want it to go through and delete all of the folders 64 00:05:13,350 --> 00:05:20,790 underneath delicious or if we wanted to rename it but only under some specific circumstance like if 65 00:05:21,090 --> 00:05:26,280 the string fish was in the subfolder name like we had a whole bunch of folders and some of them had 66 00:05:26,280 --> 00:05:32,310 the name fish in them and we wanted to delete all of the fish folders in here I would then say OK in 67 00:05:32,310 --> 00:05:33,510 that case then delete 68 00:05:36,210 --> 00:05:43,410 remove directory subfolder and we could do the same thing with all the files in the file names list 69 00:05:43,410 --> 00:05:43,440 . 70 00:05:43,440 --> 00:05:46,330 So for a file in file names you know. 71 00:05:46,350 --> 00:05:48,090 So if this file 72 00:05:50,640 --> 00:05:57,340 ended with some certain extension like we went to read all the Python source files there. 73 00:05:58,020 --> 00:06:00,780 Or maybe we just want to copy them somewhere else. 74 00:06:00,780 --> 00:06:05,370 We have like a copy function and just add the. 75 00:06:05,820 --> 00:06:12,600 And then add the old name and then you know maybe we want to rename it so that it had a new extension 76 00:06:12,600 --> 00:06:16,670 like back up or something like this. 77 00:06:16,710 --> 00:06:22,220 This is kind of tricky because remember this is just a string of a file name it's not in absolute paths 78 00:06:22,220 --> 00:06:27,600 so we'd have to call the OS to join to join the folder name 79 00:06:31,980 --> 00:06:32,970 and that file 80 00:06:34,660 --> 00:06:37,100 . 81 00:06:38,040 --> 00:06:46,200 So say we wanted to rename it to have done back up at the end of it but using code like this allows 82 00:06:46,200 --> 00:06:52,590 us to do a lot of small decision making on a lot of files thousands of files or folders. 83 00:06:52,590 --> 00:06:57,750 That's really wouldn't be possible to do with the file explorer like you know it's really easy for me 84 00:06:57,750 --> 00:07:04,320 to say oh I want to just delete the entire delicious folder so I could just highlight all of this and 85 00:07:04,320 --> 00:07:06,320 then right click and select Delete. 86 00:07:06,540 --> 00:07:12,900 But say I want to you know find all of those say all these SoBo these folders that had the name fish 87 00:07:12,900 --> 00:07:14,640 in them and just delete those. 88 00:07:14,790 --> 00:07:21,480 Then that's there's no way to just massively do that I'd have to click through every single folder underneath 89 00:07:21,480 --> 00:07:24,330 the delicious directory. 90 00:07:25,320 --> 00:07:27,800 And for this in this case that would be that much. 91 00:07:27,810 --> 00:07:33,030 But say I had a folder with thousands of files and thousands of folders in it that would take up a lot 92 00:07:33,030 --> 00:07:33,760 of time. 93 00:07:33,790 --> 00:07:42,030 So do it using this OS walk fold function allows us to write code where we can perform some sort of 94 00:07:42,030 --> 00:07:49,050 action or run some code against all of the folders or file names underneath a certain folder. 95 00:07:49,050 --> 00:07:55,050 And if I wanted to do this for all of the files on my computer which probably isn't recommended I could 96 00:07:55,050 --> 00:07:59,940 just put in the root folder name is really isn't recommended I should probably do a dry run first by 97 00:07:59,940 --> 00:08:11,120 commenting out this code into printing something like You know I'm removing this directory. 98 00:08:11,490 --> 00:08:17,520 Same thing here where I can print out a message saying I'm copying this file to this new file name 99 00:08:20,370 --> 00:08:24,290 but there's a lot of functionality that you can use in OS start walk. 100 00:08:24,360 --> 00:08:31,050 Just remember you all use Start Wachs return value in a for loop and that returns three different values 101 00:08:31,050 --> 00:08:32,320 on each iteration. 102 00:08:32,520 --> 00:08:38,100 The folder name of the current folder it's looking at all of the subfolder is a list of strings for 103 00:08:38,100 --> 00:08:44,470 the sub folders inside this folder and also a list of strings for the file names inside that folder 104 00:08:44,480 --> 00:08:44,990 .