Python Jumpstart by Building 10 Apps Transcripts
Chapter: App 9: Real Estate Analysis App
Lecture: Sketching out the Real Estate Data Miner App

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0:00 All right, let's write the first part of our real estate data mining application.
0:04 And we'll follow my standard convention of having a main method, at the top here,
0:09 and then using the main live template in PyCharm,
0:13 just sort of use the proper import safe way of invoking it,
0:17 now we are going to do a couple of things,
0:19 we are going to as always define a print_header()
0:21 and we'll just print out some basic stuff as usual,
0:25 so here is a standard header which we'll call from up here,
0:28 the next thing we need to do is get the data file,
0:32 so let's write a method not the actual data but just the file name for the data,
0:37 so notice down here,
0:39 let's talk about where are we getting our data from,
0:41 we have a data subfolder next to our program,
0:43 and we have the Sacramento real estate transactions for 2008,
0:47 so this turns out to be all of the real estate transactions
0:50 that I could find for Sacramento in 2008.
0:55 Personal individuals, no business stuff.
0:57 So we want access to this file,
0:59 now we want to use again our OS
1:01 so we'll import OS and a lot of times we've been saying .path, .join
1:05 and we would give it something like '.' for the current directory
1:08 and then we would say data and then we would say the name of this,
1:11 in PyChrm you can hit ctrl+t and it gives you a rename
1:14 which is probably the easiest way to just copy the name there,
1:20 but this '.' assumes that we are always using the working directory
1:24 just above the data folder,
1:25 we always want to look right next to this program for its data
1:28 no matter where it's running so let's get the base folder in different way.
1:33 We'll say base_folders os.path.dirname() and remember,
1:38 there is an __file__, a __file__,
1:42 implicit variable for every module that's going to say here is the full path,
1:46 so we get the base folder and then we can just put base folder here, right,
1:50 so now it doesn't matter where we are running our code,
1:53 we'll always get back to this, and then we'll just return that,
1:57 let's do a little format really quick, and let's get the file it's called filename
2:01 say get data file and then just let's print this out really quick.
2:07 All right, that looks correct, I have it on my desktop
2:09 and then here is our 09 real estate data and so on.
2:13 Perfect, so that should work for getting us the file
2:15 now the next thing to do instead of this is to actually load the data
2:19 so I'll just say data like this and we'll come back to what that means,
2:23 I'll just say load file, so we are going to do this in a couple of ways,
2:28 we'll start out with like really basic way
2:30 and then we'll come back and do a little bit more.
2:38 Ok, so we got our data sketched out,
2:40 and the very last thing that we are going to do, after we loaded up,
2:42 maybe we'll print it out for a minute but I guess we can go and write query data
2:47 and that will just spit out the report and so on so feed it data, like so,
2:52 and that's the last method we'll write, and then, move on.
2:56 So there we have the basic structure for our app
3:00 and I don't know if I have shown you this for a while in PyCharm
3:02 but over here you can actually see the structure
3:04 and jump around if you like that's kind of handy,
3:07 even better when you have classes and hierarchies and these sorts of things,
3:10 so next we are going to work on load data and actually parsing our csv file.