1 00:00:00,270 --> 00:00:08,370 So in many physics programs you to very demanding calculations and then only afterwards you think about 2 00:00:08,370 --> 00:00:09,930 what do you want to do with the data? 3 00:00:10,140 --> 00:00:12,210 Which type of processing do you want to do? 4 00:00:12,900 --> 00:00:18,600 So of course, it would be very unreasonable to redo the whole calculation every time. 5 00:00:19,140 --> 00:00:25,530 So at some point you want to store your data so that you can load the data later on without having to 6 00:00:25,530 --> 00:00:26,760 recalculate it. 7 00:00:27,450 --> 00:00:32,549 And we want to do this here with our store list from the previous section. 8 00:00:33,480 --> 00:00:38,160 So I want to show you, how can you save these numbers in a file? 9 00:00:38,160 --> 00:00:40,650 And I want to show you several methods how this works. 10 00:00:41,790 --> 00:00:49,170 So the first thing is that I want to show you how you can save the whole thing at once. 11 00:00:49,980 --> 00:00:58,890 So the component here is that it relies on Nampai, so it's a can and p command and p dot and it's called 12 00:00:59,160 --> 00:01:01,420 safe text or safe text. 13 00:01:02,280 --> 00:01:07,770 And then the syntax is the following you just write store lists. 14 00:01:09,120 --> 00:01:11,430 So basically you give the string for for you. 15 00:01:11,430 --> 00:01:14,040 A file that will be created stored is one dot. 16 00:01:14,260 --> 00:01:19,590 Yet, for example, you could also name a text or some something you like. 17 00:01:19,590 --> 00:01:23,100 It doesn't really matter, but typically you call it something like that. 18 00:01:24,210 --> 00:01:29,880 And then you write the variable that you want to plot or that you want to export. 19 00:01:30,330 --> 00:01:33,270 So in our case, that's what that will be used to store list. 20 00:01:34,320 --> 00:01:44,430 And then something that I found really useful is to add another option, which is formats and the format. 21 00:01:45,360 --> 00:01:46,710 You write something like this. 22 00:01:47,670 --> 00:01:51,120 So what it means, I will show you in a second. 23 00:01:52,080 --> 00:01:59,340 So we run this and it will create a new file in the same directory where your notebook is stored. 24 00:02:00,810 --> 00:02:06,060 So now let me show you what happens if I do the same thing without the format option. 25 00:02:06,960 --> 00:02:11,340 So let's call it stolen two and run this as well. 26 00:02:11,650 --> 00:02:13,770 And now I will show you what happens. 27 00:02:14,460 --> 00:02:19,920 So here you see, the output of all is one with the optimal form and commands. 28 00:02:20,160 --> 00:02:22,470 So this will just be our integer numbers. 29 00:02:23,340 --> 00:02:30,750 And here you see the output of Stal is two, which will be your floating point numbers even with this 30 00:02:31,560 --> 00:02:33,290 10 to the power of one here. 31 00:02:33,300 --> 00:02:35,970 So I think this is not really so useful. 32 00:02:36,240 --> 00:02:41,940 But of course, if you are using floating point numbers, then it's of course better to have such a 33 00:02:41,940 --> 00:02:42,390 formant. 34 00:02:42,690 --> 00:02:52,950 But even the optimal tag empty percentage as also works well with floating point numbers. 35 00:02:53,370 --> 00:02:59,220 So I recommend always using this format so that it will always give you a reasonable output. 36 00:03:00,300 --> 00:03:05,160 So now let's get back to our Jupyter notebook, and let's close these two facts of what we have done 37 00:03:05,160 --> 00:03:12,510 here is we have taken a finished list and we have saved the whole list at once in the new file. 38 00:03:13,410 --> 00:03:19,530 But sometimes, especially if it's a very, very long calculation and you want to check in between what 39 00:03:19,530 --> 00:03:25,770 is the results, or even if you are afraid that your calculation may crash and may stop at some point 40 00:03:25,770 --> 00:03:31,110 and then you lose all the data because this one hasn't finished and you couldn't export it. 41 00:03:31,800 --> 00:03:36,030 So in these cases, it's always better to save one line after another. 42 00:03:37,110 --> 00:03:41,760 And you can do this in several methods, of course, and I want to show you here two of these. 43 00:03:42,270 --> 00:03:45,870 So the first one would be to, first of all, open a file. 44 00:03:47,160 --> 00:03:56,160 So, for example, we could write store list three point eighty and then we provide another argument, 45 00:03:56,160 --> 00:03:57,630 which is W-4, right? 46 00:03:57,900 --> 00:03:59,880 So this allows us to write in this file. 47 00:04:00,120 --> 00:04:04,380 And also it means that when this file doesn't exist, it will create the file. 48 00:04:05,400 --> 00:04:12,690 So now, in order to work with this file, we must store this command in a variable, or we must give 49 00:04:12,690 --> 00:04:13,650 it a name, basically. 50 00:04:14,160 --> 00:04:21,839 So I call this file and now we can access the file by writing something like file dot, right? 51 00:04:23,250 --> 00:04:25,590 So we can write file dog right. 52 00:04:25,590 --> 00:04:30,170 And we can now write some, yes, some stuff, for example. 53 00:04:30,180 --> 00:04:30,480 Hello. 54 00:04:32,130 --> 00:04:38,190 So this is especially useful if you're working with loops, as we have learned in the previous section. 55 00:04:39,030 --> 00:04:41,640 So here we'll use a for loop, so I will write. 56 00:04:42,510 --> 00:04:45,240 Let me maybe just copy this one here. 57 00:04:45,480 --> 00:04:49,500 So let me redo the calculation from here. 58 00:04:49,500 --> 00:04:57,240 So I write for I in range one, two, six, and no, I don't want to store the data in a list, but 59 00:04:57,240 --> 00:04:59,430 instead I want to write. 60 00:05:00,620 --> 00:05:03,770 This to the files I write file DOD, right? 61 00:05:05,560 --> 00:05:13,450 So I could now try to run it like this, but I think it will not work so well, let's see. 62 00:05:14,470 --> 00:05:14,800 Yeah. 63 00:05:14,980 --> 00:05:19,570 So the error will be that the right argument must be a string and not an integer. 64 00:05:20,350 --> 00:05:25,480 So what we can do quite easily, we just convert this number to a string. 65 00:05:25,900 --> 00:05:26,920 I think this was wrong. 66 00:05:27,160 --> 00:05:27,790 It's not correct. 67 00:05:28,000 --> 00:05:29,080 Of course it's string. 68 00:05:30,400 --> 00:05:31,910 So now I think it has worked. 69 00:05:31,930 --> 00:05:34,010 So let me check what the file looks like. 70 00:05:34,660 --> 00:05:36,640 So, yeah, it worked. 71 00:05:36,640 --> 00:05:39,180 But it didn't really give us the result that we wanted. 72 00:05:39,180 --> 00:05:45,070 It basically just printed all of the strings, just one after another and not in a new line. 73 00:05:46,060 --> 00:05:47,890 So, yeah, that's a bit problematic. 74 00:05:48,610 --> 00:05:50,890 And also, there's another thing that I want to show you. 75 00:05:51,220 --> 00:05:56,890 So when I tried to open the file after running the command and I just wrote down, it gave me an error 76 00:05:56,890 --> 00:06:02,830 message that I couldn't open the file because it was currently being used in the Python notebook. 77 00:06:03,280 --> 00:06:04,750 So let me show you what I changed. 78 00:06:05,080 --> 00:06:12,370 But the problem was that the file was still open because I just wrote open the file and then we wrote, 79 00:06:12,580 --> 00:06:13,680 but we never closed it. 80 00:06:13,720 --> 00:06:17,620 So this was why I got the error message that I couldn't access to file. 81 00:06:18,150 --> 00:06:20,920 That's what I had to add here is I had to close the file. 82 00:06:21,520 --> 00:06:25,060 But of course, be careful and do not write this into for a loop. 83 00:06:25,060 --> 00:06:26,470 So do not write it here. 84 00:06:26,950 --> 00:06:33,070 This would be pretty bad because then you would close it right after the first loop and then you can't 85 00:06:33,070 --> 00:06:34,210 write in the file anymore. 86 00:06:35,470 --> 00:06:41,560 And then to solve our other problem that we have all of the characters just one after another. 87 00:06:41,920 --> 00:06:45,670 We just have to write a line break. 88 00:06:46,480 --> 00:06:49,570 And this is just like in HTML. 89 00:06:49,570 --> 00:06:52,870 I think you just write the following commands backslash. 90 00:06:53,050 --> 00:06:56,590 And so this is the command for a line break. 91 00:06:57,400 --> 00:07:00,160 So I think if I run this now, it should work. 92 00:07:00,640 --> 00:07:01,420 So here we go. 93 00:07:01,450 --> 00:07:03,700 We have now our five numbers. 94 00:07:04,120 --> 00:07:06,460 Just one number in every line. 95 00:07:07,420 --> 00:07:15,790 So now let me go back to the to the course and let me show you another method how you can save this 96 00:07:15,790 --> 00:07:16,810 data in the file. 97 00:07:17,260 --> 00:07:20,140 And this method is just a bit shorter. 98 00:07:21,100 --> 00:07:24,550 So here we use something called the width command. 99 00:07:25,750 --> 00:07:27,010 So we write with. 100 00:07:28,670 --> 00:07:29,250 Open. 101 00:07:30,110 --> 00:07:40,820 And then we make a new file, which we call Story List four, and we open this as a file and then we 102 00:07:40,820 --> 00:07:42,440 can write here our commands. 103 00:07:43,040 --> 00:07:49,220 So basically, this means just in this blog, just for these commands, we have to file open and we 104 00:07:49,220 --> 00:07:51,110 call the file file. 105 00:07:51,740 --> 00:07:57,290 So I could write you also something else, for example, test, then our file would be called test. 106 00:07:58,100 --> 00:08:00,740 So now just in this block, we can write in the file. 107 00:08:01,490 --> 00:08:09,680 And now what I do is I just copy this one and paste it here, and I think this should also work. 108 00:08:10,280 --> 00:08:17,390 And here we don't even have to close the file because it means just in the block, we have to file open. 109 00:08:17,720 --> 00:08:23,480 And that means while the block is running or while the loop is running, it's open but wants to loop 110 00:08:23,480 --> 00:08:24,470 has finished and wants to. 111 00:08:24,470 --> 00:08:25,460 Whole block has finished. 112 00:08:25,730 --> 00:08:28,160 Then the file will be closed automatically. 113 00:08:28,880 --> 00:08:31,040 So let me run it and see what happens. 114 00:08:32,090 --> 00:08:33,340 So once again, it worked. 115 00:08:33,350 --> 00:08:37,340 We have our five numbers one, four, nine, 16 and 25. 116 00:08:38,570 --> 00:08:45,020 So we have now learned how to store data and files by basically three different methods. 117 00:08:45,500 --> 00:08:52,450 And I would say this one is most easy, but these ones are sometimes a bit more useful because, yeah, 118 00:08:52,640 --> 00:08:57,410 you always write in the file while you calculate and it's much safer. 119 00:08:57,410 --> 00:09:02,630 And also, yeah, you can check while you're calculating what is the result. 120 00:09:03,650 --> 00:09:07,790 Now, of course, we do not only want to write in the file, we also want to load. 121 00:09:08,240 --> 00:09:14,930 And for this, I will use the command and p note text, although to text. 122 00:09:16,010 --> 00:09:22,430 Now we must specify which file we want to load, and I just will load the data from one of our files 123 00:09:22,430 --> 00:09:28,700 and we have just created which is in the same directory so we can just write this and we must, of course, 124 00:09:29,090 --> 00:09:30,260 assign a name to it. 125 00:09:31,610 --> 00:09:33,500 So this will be our loaded list. 126 00:09:35,000 --> 00:09:37,300 And now I can check if this really worked. 127 00:09:37,370 --> 00:09:43,610 So I write node list and it gives me the array one, four, nine, 16 and twenty five. 128 00:09:44,690 --> 00:09:49,670 And of course, I could now continue and work with the data that we have just loaded. 129 00:09:50,300 --> 00:09:56,990 For example, just write a lot of lists zero and it will give me the first entry, which is one dot 130 00:09:56,990 --> 00:09:57,500 zero. 131 00:09:58,310 --> 00:10:00,470 So you see, loading data is pretty easy. 132 00:10:00,620 --> 00:10:07,280 If the data stored in the correct format, so I would always encourage you to use one of these methods 133 00:10:07,280 --> 00:10:11,090 so that you have your data one number in every line. 134 00:10:11,090 --> 00:10:13,970 So then there will be no problem when you load the data.