Python Jumpstart by Building 10 Apps Transcripts
Chapter: App 5: Real-time weather client
Lecture: The web is a messy place, let's clean it up
0:01 Ok, so we've downloaded these and we've printed them out,
0:03 let's go back to printing out the location again,
0:05 and if I go 97201 get the weather in Portland
0:08 you are going to see the print out is not lovely, here we go,
0:11 you can see this huge long stream and lots of new lines,
0:14 is actually partly cloudy bit here,
0:17 so what we want to do is clean this up and now that looks like it printed ok
0:21 but you know, as the page evolves
0:23 maybe it has like white space around the edges
0:25 this is definitely not ok and we don't really need to list the zip code
0:29 because we typed it in we just want this part
0:31 so let's work on cleanup all these pieces of text first
0:34 and then we'll pull out just the city and state.
0:37 So we can come down here and say
0:39 that the location= cleanup_text of the location
0:43 Now this is a method that we are going to write,
0:45 not sure it justifies its own method but maybe it does,
0:49 so we are going to come down here and say
0:51 first of all if you ask us to clean up text
0:53 and the text is none we try to interact with it
0:56 that is going to be a crash so we'll do a little error handle,
1:00 we'll say if not text and use the truthiness of strings,
1:04 remember if they are empty or none
1:07 they will be false so we'll just return text,
1:10 but if they are not empty then we can do some processing,
1:13 we can say text = text.strip() and strip is a built in method to the string class
1:18 that will take all the white space tabs, space, new line, \\ end type of things,
1:24 off of the front and the end, there is also an L strip and R strip, and so on
1:28 so we are going to modify this and then we'll return the text here.
1:32 The other thing that we might want to do is if you are new you are like well,
1:35 how do I know there is a strip,
1:37 when I hit. does it say strip, no,
1:40 so we can use something called type hints in Python
1:43 now these have no effect on the runtime behavior
1:46 but they will give you better intellisense
1:49 if I am certain this is a string I can say colon then a class name,
1:53 I can say str that's the class of a string in Python,
1:56 if there is an int I could say int and so on,
1:59 but I'll say str there is string
2:01 and now when I go down here and interact with this in PyCharm
2:04 it will actually give me things like strip,
2:07 they justify L strip R strip,
2:10 so PyCharm knows now that we told it hey this is a string,
2:13 it's going to give us help as if it were a string.
2:16 Again, I could pass a number here
2:18 and it's not like there will be a compile error,
2:21 remember there is no compiler,
2:23 but it does help people who use this method
2:26 as well as the tooling understand what it is you are trying to work with
2:30 so for sure it's a string we can say str
2:32 and that will give us some help if you want it.
2:35 So let's continue here, and do this for the condition,
2:41 do this for the temp and finally the scale.
2:45 Those look like they are ok
2:48 but you never know what is going to happened to them.
2:50 Now if we run this again, we'll be in a slightly better place.
2:54 Ok, look, partly cloudy, here is the temperature
2:57 the scale and then we still have this,
2:59 but that's much better than that huge long ten line bit of text.
3:04 So the last thing we need to do is actually pull that piece out.
3:08 So we want to go down here and say we want to do one more thing to the location,
3:14 we are going to say find the city and state from location,
3:20 and we'll pass the location here,
3:21 so this is a function we are going to write,
3:26 and let's go ahead and get some help form intellisense
3:29 just so you guys can see it,
3:31 now the location is a string and we are going to use
3:34 this method here on it called split,
3:37 so what split does is it will take some character
3:41 in this case we are going to say \n for the new line,
3:44 but it could be a comma if you had a string
3:47 with a bunch of comma separating them,
3:49 and you want to just the individual words you can say comma
3:52 but words separated by new lines so we are going to say new line
3:56 and what we'll get back is a list that contains just the elements of the string,
4:00 that are separated by these items,
4:02 so we'll call this parts like this, and then we are going to return parts of 0.
4:07 This is assuming that the shape of this thing is correct
4:10 it might not be good if it's not- anyway,
4:12 we are going to return this and one more time we might want to
4:16 strip off the characters on here because there is still maybe
4:18 some white space in between.
4:21 Ok, so let's try this one final time,
4:23 do a little cleanup on the code, run it, all right, go in,
4:28 and perfect look at that, we have partly cloudy,
4:33 the temperature is 8.6 degrees,
4:35 scale is Celsius and the city and state are Portland, Oregon.