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MALE_1: I am going to
do a walk through on
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the JSON to CSV assignment.
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What I've got here,
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I've started in pie
charm and I just added
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our import CSV and import JSON,
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and then according to
the assignment we need
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to include within
the main function.
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I've added the if__
name equals the main,
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then we invoke main.
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Let's go ahead and
start coding for main.
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First thing we want to do
is open up the JSON file,
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which is called
station-data.json.
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I'll start off here and let's
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do a file handle equals open.
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We'll start typing in
station groups right there.
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Station, at that again,
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I should be getting
an auto complete,
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for some reason I am not.
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Station data. I know why.
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Let's put in quotes.
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There we go. That's better.
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Now we're just going to
do this in read only,
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so we'll just do an R mode
option there on the open.
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That should open up our file.
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Now JSON is essentially
dictionaries, has keys,
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and the format of
a dictionary is
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pretty much mimics a dictionary.
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What we first want to do is
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we need to parse
and load this from
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the JSON module so we
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can [inaudible] the
variable to hold the parse,
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so into stations equals and
we'll invoke json.loads,
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and we want to pass
in that file.read.
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Auto complete can be really
obnoxious sometimes.
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Get rid of the extra
parentheses. Now we got that.
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Now we want to, well,
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that's pretty much
all we want to
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do in main except for we do want
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to have a couple
more functions so
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that we'll come back to
main and invoke a function.
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We actually want to alter
the data and we need to
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process the data
and then alter it
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because we're going
from JSON to CSV.
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Let's see what we
want to do here.
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Actually, going back to the
assignment for a minute,
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says the code should include
at least three functions.
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Let's make sure we do that.
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Let's first define
a function here.
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We'll call it process stations.
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And we'll just take an argument
here of the station data.
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In the station data, well,
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the first thing we can do is
create another file handle,
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and let's just call
it, so it makes sense.
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We'll go CSV.
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I was going to do out file,
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I guess that's fine too.
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Out_file equals that.
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We give it a name.
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Sorry, we just gave it a name.
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Now you want to open and then
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we'll give the actual file name,
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which will be outputfile.csv.
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In this case we'll do a mode of
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w as the file doesn't exist,
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that will automatically
create it for us.
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Screen of the variable and get
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our keys from that station data,
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the station data element(0).keys
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which should be the headers.
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That is a function there.
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Now we want to do a CSV writer.
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A variable called
CSV writer equals,
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and then now we'll
use the CSV module
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and we'll invoke
that top function
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right there, the
dictionary writer.
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We'll pass in that
file we just created
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the out_file variable
and then we'll
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indicate that our fieldnames
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equal those keys that
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we just put into
the names variable.
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Now what we will want to
do is go into a four loop.
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Four, and I like to imply for
each item or each station,
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we don't type in each,
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for each station,
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again the station data.
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We'll create a variable,
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let me say, astation,
I guess equals.
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Well actually let's
stop right there from
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minute because we need
another function right now.
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I'm going to just stub this in.
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We don't have errors.
Let's actually
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come back to main from minute,
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make sure we get this complete.
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We want to invoke
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process stations and passing
that data right here,
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this variable, that function.
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I'd like to just include
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a little message
after everything
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is all done so we can
just print completed.
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Good enough. Now we
actually want to
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do probably at least one
or two more functions.
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Well, we actually do need
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two more functions because
that's part of the assignment.
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If we look at the station data,
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the assignment indicates some
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of the things that we need
to do to clean up the data.
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If we go back to the
assignment, it says,
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let's see, if the value
type is a percentage,
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then convert the value to a
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floating point
with two decimals,
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accuracy, then convert
back to a string.
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Sixty two percent should
be converted 2.62.
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If the value type is a number,
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then removes from
the output a number.
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Example 13,493 should be
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converted to the same,
but without the comma.
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That should be easy.
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Let's do a function called,
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let me just do change_percent.
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This will take a value argument
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and up that in for a minute.
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Then we'll also do another
one called alter_values,
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and that will also take
in argument for item it.
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Just put it pass
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here.
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Let's first do change percent.
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All we're going to do here is
look for that percent sign
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and get rid of it and
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then we're going to
convert this to a float,
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convert it from a percentage
to a decimal thing.
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Let's see here,
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we'll do a verbal to read
the percent equals value.
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Well, first of all we can do
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a simple replace and
we'll do a replace.
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Then we're looking for
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the percent sign and
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we want to replace
that with nothing,
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so that way to do that.
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Now, we want to
do a float value,
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because the type here is
going to be a string.
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We want to convert it
to a float and then we
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will divide that by 100 to
convert it to a decimal form.
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Wow, that take care of that.
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Now, we also want the
point two precision.
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We can use that with
the format function.
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Should be pretty nice.
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A couple of different
ways we can do that,
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I think the format function
will be the easiest.
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We can also do convert it to
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integer and float could
do the same thing,
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but this is the easiest so let's
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do float value equals format.
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We'll pass in the float
value and then we want to,
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it says.2 precision,
so we can just.2fs.
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If we want three
decimal precision,
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we can go just
different precisions
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that way if you're not
familiar with the format.
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That function is done.
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All we need to do is return
that back to the caller,
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and I think we can mark
that when we're done.
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Now, alter values we want
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to look for the word percent
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and we also want to look
at the word number.
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Because if we look
at the json file,
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depending on if the value
type is percent or number.
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In there, you can go if item,
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now the header let's call it
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value type that equals percent.
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We can do something
down the item.
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Now we want to actually
modify the value of the item,
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so value equals,
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and then we will invoke
that function we just wrote
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the change percent and we'll
pass in the item value.
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I
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got
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it's tech error or
something here.
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Let's see, value equals change.
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Oh, I know, that's why.
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Too many equals. If the
value type is not percent,
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we need to handle the
other one which is
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the value type equals number.
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This one is really easy,
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we could put this in function,
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but don't really need to
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because it's just a
one line thing here.
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We could alter this item to
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item value equals and
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then we'll just
replace that comma.
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We got value.replace.
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Then we can do replacing
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the comma and then we'll
replace it with nothing.
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That could be it there.
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Then we'll just return
item back to the caller.
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Now, I think we're good there.
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Now we can go back to our for
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loop and just start
accessing those.
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We just access this
function, alter value,
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so for each station
in station data and
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for astation equals
invoke alter values.
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Pass in the station item
that's in our loop there.
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Then all we really want to do at
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this point is write
it out to the csv,
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so csvwriter.writerow and I
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send that variable astation
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and I think that
will do the trick.
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That should be it. Let's get
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this to go and see how it runs.
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It looks like I've
missed something up
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here in the change percent,
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I've got this unused variable.
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I see what I did here.
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I accidentally use value
inside here. We clean this up.
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We want to get rid of
that percent sign.
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That should fix that problem.
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To replace percent
equals value.replace,
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we've got that in here
and now we're going
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to convert it to a float,
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divide it by 100 to a decimal,
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do a precision, return
it back to the caller.
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I think we're good now.
Let's go ahead and run this.
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Now, this is going to go into
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a file called output file.csv.
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We already have the
station-data.json,
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I don't have the
output file here.
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Let's go and run this.
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Nice. We'll ran and
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I just saw there's the
output file there.
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I'm going to go ahead
and open this in finder.
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I wonder if I can
just open it up.
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We can go. There we have
it. That looks good.
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Like I said, we can change
the precision and stuff here.
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If you want to tweak that.
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Go through the data there,
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everything looks pretty good.
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Then we could also
open this in Excel,
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or numbers on Mac.
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I hope you find that helpful.
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That's it. Exit.
