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In this and in the next lecture, I'm going to show you how you can work with text files on the flash

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based file system of the ESB 32, the HP 32 has about one and a half megabytes of available space on

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its flash base file system, as I said.

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And you can use that space to store programs, but also to store files in those files can contain sensor

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data.

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Perhaps he can use this capability as a sensor data logging feature, but you can also use it to store

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other text files that perhaps contain configuration.

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You have already done something like this in the past in the section on Wi-Fi where you stored the Wi-Fi

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network's credentials in a text adjacent file.

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In this lecture and in this example here, I'm going to first show you how you can create a CSP file.

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That is a text file that contains multiple rows where each wrote stores data separated by a comma.

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And then in the next lecture, I'll show you how to read out that data.

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So once you have a data file like that on your to stored on its file system, then you can use a tool

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like Thorney to export it and then be able to manipulate it.

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See with a spreadsheet perhaps of some of the text processing program on your computer.

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Or you can read out data from a text file and transmit them to an online service.

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It could be, for example, Google spreadsheet for of device storage.

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So let's begin this example by looking at the first script in which I demonstrate how you can create

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actually file.

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This script actually contains two parts.

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And I'm going to talk a little bit more about this in a moment.

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The first part has to do with statistics.

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So there's a few tools that Microplace then provides that allow you to do things such as find out how

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much space total space is available on the petition that you are able to use to steal files.

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But you can also go down to the level of the individual file and find out how many bytes it contains.

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And those tools together allow you to keep track of the size of, in this case, a text file so you

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don't run out of space.

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And this is something that you want to manage either through your script, keeping a tally of how big

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a file gets or periodically checking to see if a storage file facility file becomes too big and then

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just reset it to copy its data across the computer and to delete it from the device.

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Because remember, again, the ESB 32 flash is about to make it right in space, but is used for other

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things as well, including your programs.

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So you end up with about a bit more than a megabyte.

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So that's what happens here.

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We get a few statistics and actually I'm going to play around with these functions as well on the shell.

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And then in the second part, so line 54 onwards is where the actual writing of dummy data.

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See, I'm using the random function here.

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We are adding some dummy data onto this file in a committed, limited format.

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In terms of the things that we need to consider, I'm reporting random can generate some random data

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so we don't have to complicate the so good with sensors then importing the petition from the E.S.P three

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module so I can just demonstrate how we can call this function in particular petition info, which gives

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us a variety of information about the petition that we are using to write our file in.

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And I'm also using the E.S.P module so that I can demonstrate how to use functions such as E.S.P flash

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size excuse me, the total available size of the 32, but also micro OS.

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So this is the micro python version of the OS module that comes with C Python, which allows us to grab

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statistical information about a specific file.

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So this is actually the function that is most useful out of all of the functions that I mentioned so

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far, because this function specifically allows me to get information about how many bytes are stored

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within the file that I'm working with this example and I'm just going to add to the extension because

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that is important.

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All right.

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Now, in terms of actually writing the data in this text file, I'm going to start with just creating

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a variable that holds the name of the file.

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And then I'm going inside a loop here.

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I just want to write ten new rows that contain dummy data or create some random numbers supposably for

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the temperature, humidity and atmospheric pressure.

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Then I'm using the open function, and that's the same a function that is integrated into micro python.

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We don't need to import a particular library at this function.

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So passing the filename across is the first parameter and the second parameter is a modifier that indicates

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what kind of access we want to have to this file.

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I'm using a here to indicate that I want to append if I use W and every time that the program runs,

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it would replace the existing content and write new content would overwrite data.

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In this example, I just want to append data and notice here I'm looking at the Micra Python device

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file system and this file does not exist yet.

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So because it doesn't exist yet, the A modifier will create it.

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And from that point onwards, it will continue to append data to the end of this file sort of operating.

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I've got information about the various types of money fires are going to blow up here, so if you go

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to the python open function.

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And at the market, python, but the normal python c python function, because that's where all the

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information is it C I believe it's this one here and these are the modifiers.

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So I'm using a Pente for this example, but now you know what the others do as well.

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All right.

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Next.

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I'm creating another variable here.

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This is just their variable contains string, and I'm using the format function that allows me to have

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in between double quotes of code and the curly bracket notation, which are simply placeholders.

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Then I can have whatever other text, the one in between those placeholders in in this case, I'm creating

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a record for my seat to be filled.

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So all of the values that I am storing this single record which use a single line, needs to be separated

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or need to be separated by commas.

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And in the end, I've got the new line special character so that I've got a new line in the end of this

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record.

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And then as parameters for the format function, I've got the three random numbers, a temperature and

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humidity and the pressure.

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So as you can probably guess, this individual numerical values will be placed inside those placeholders.

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And you see this in action in a moment.

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I also have that string that I want to store in this new text file.

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I can use the right function to write the new line at the end or pended in the end of the text file.

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And every time that I finish and you write a much closer file to make sure that it's not damaged in

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any way.

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So open the file.

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Create the thing that I want to write the text string and write the text at the end of the file and

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then close the file.

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And in the end, I'm also grabbing the statistics for the file.

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Again, I'm calling again the stat command or the stat function in the micro OS module.

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Partly filename is filename appear.

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I get back a table.

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This table contains a number of statistics and one of the statistics say in index position six is the

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number of bytes that are now contained in the file.

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So I'm doing the same thing up here.

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I'm getting the total number of bytes stored in the file before I do the right and the right.

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And then they take the same statistics again to see what the effect on the size of the file has been.

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Again, to know more about the stat function.

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You can have a look at these locations, documentation there.

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All right, I'm going to go ahead and run this file and notice that here we will be seeing a new text

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file up here and we'll have a look at the statistics have come out.

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So the script could have dug perhaps in line 50.

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Let's see what's happening here.

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So I'll see what happened.

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I tried to get statistics for a file that does not exist.

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So what I'll do the first time that I run this script, I will just come to the Senate.

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I can write a bit of code here to check that the file exists before I get its statistics.

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But for the sake of this example, I'm just going to come and down these lines for now.

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Play again.

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Very cool.

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All right.

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Now let's see.

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New file should appear.

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Need to refresh.

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They go to his text file and it looks like he's I've got 10 rows of sample data through dummy data.

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Now let's run this program again.

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But before I do so, I will uncommented the stats lines.

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And just remember that we are going to spend so can have more data here, another 10 Roshe would appear.

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To play.

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All right, so size before the new ride was one hundred and four bytes, after it was 206 six points

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and can close this file and reopen it.

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So there there's the twenty nine in total.

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So let's have a look at a couple of examples here.

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Again, I'm going to import Mike Rowe is the model and I'm going to import this line here for the file

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name.

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And.

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Can you grab the statistics from here and have a look at the full stats available so there's a couple

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there's a bunch of things that also appear here, but the one that I'm interested in is this.

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This is the only one that makes sense for the purposes of this example.

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This how big is the file?

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And that is in bytes.

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This is an opposition index six so zero one, two, three, four, five, six.

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And I can use a.

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Command like this to get troops, to get the number that I need out so you can imagine if you are interested

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in keeping track of how big this file is, then you could have a bit of logic here to let you know if

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perhaps the file grows to be on a couple of thousand bytes.

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And that would be an indication that you need to empty the file, copy the data across to your computer

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and clear the contents of the text file.

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All right.

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Now, other things import the E.S.P module.

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And to have a look at this function, flash size, and this gives you the total flash size, a bit about

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four megabytes, but of course, you're not able to use this full amount to store programs or text files

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instead.

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He micropayment confines you to the running partition, so I've just imported a partition module and

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then I can create a partition object.

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Some passing the petition, but running constant here to the petition constructor.

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So let's have a closer look at the documentation for the petition module.

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So according to the micro python documentation, I'm now looking into the SB eight to six six and SB

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two functions.

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And down here you'll see that we've the constants and the four types of petitions that are available

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on running type app and type data.

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And the one that I'm looking at here is running.

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This is where we can actually store data is managed by our program.

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So the size of the running petition, we can print it out.

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By calling the info function and that printout out another couple and you can see that its size, this

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number here indicates that a megabyte and and a half of the available space in the running petition

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anyway, all those numbers are not really useful.

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The one that I think is mostly useful for us.

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Are file specific statistics that are available through the micro OS module.

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All right, so now we've got our text file and we've got a comma delimited there are stored in our text

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file.

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So let's move on to the next lecture where I'll show you how to read it.