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We are now within sight of the finish line. We're onto the last step.

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So this is the solution for step 4. And in step 4

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we want to be able to improve our program so that the words where the user

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clicks the checkmark to means they already know that word.

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They know what it means and they don't wanna see it again in this list.

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So what we want to be able to do is to remove the words that the user knows from

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this dictionary of words to_learn. And to do that,

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we have to change this command. When the user clicks on the unknown button,

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we're going to simply just give them the next card,

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which is a random word from the list of words.

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But when they use it clicks on the known button,

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instead of clicking on next card, we're going to call a different function

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which I'm going to call is_known. Now is_known

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is going to be a function

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that's going to remove the current card from the cards that are in the list of

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words to learn.

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So what we're going to do is we're going to get hold of our list to learn,

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and then we're going to call the remove method.

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And then we're going to remove a particular element from it.

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And that happens to be the current card.

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So remember, the current card is a dictionary

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which we got by randomly choosing from our list to learn.

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So now, when the user says is_known,

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then the current card is going to be removed from the list of words to learn.

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And then after we've done that,

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then we're going to call next card from this particular method. At the moment,

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if we run this code and I just keep clicking the check mark,

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eventually, we're going to have a very small list of words that we're going to

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pick from. In fact,

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if I go ahead and print the length of my list, to_learn,

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you can see that the first time I run this code and I click on the is_known

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button, we have a hundred words. But if I keep clicking on this,

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then you'll see that every single time,

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I'm just reducing that list because I'm saying,

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I already know what this word compris means

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and that word is now taken out of my list of words to learn.

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So now that list is smaller by one entry.

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Now this works right now, but if I rerun the app,

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then you can see it goes back right to the beginning

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and it has a hundred words again.

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So in order to keep hold of the words that I still need to learn,

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I have to save this list to a new permanent file

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each time the user clicks on this is_known button.

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So the way that I'm going to do that is by using pandas again.

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I'm going to use pandas to create a new data frame.

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And that data frame is going to be created from our list to_learn.

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Now, I'm going to save this as our data,

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and then I can say data.to_csv in order to save it as a CSV file.

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So I'll call this words_to_learn.csv.

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So now, if I press my check mark

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and I take a look within my files,

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you can see that words_to_learn.csv is created.

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And at the moment it's got 89 entries. But if I keep clicking this a few times,

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it's going to reduce each time.

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So this is now a permanent storage of all the words that I have yet to learn.

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But I don't really want it randomly in the middle of my project.

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I want it to be saved alongside my french_words.csv.

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So I have to change this to a file path

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which is going to be data/words_to_learn.csv.

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So let's go ahead and delete this file and do refactor.

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And then we're going to run this again.

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And next time you'll see that it appears in the right place.

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Now, in addition to saving it to CSV,

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we also have to read from that CSV because instead of using the words from our

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original list which is our french_words.csv,

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I actually want to be able to read from my words_to_learn.csv instead,

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because that way, every single time I rerun the app,

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it's always going to give me all the words that I've yet to learn.

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So currently we're on 87. If I run this again,

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you can see that the first time I click on this,

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it's going to go to 86 instead of going back to 100.

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But there is a problem here though

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because if I delete this file, words_to_learn.csv, and I go ahead and run this, the first

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time this runs it's going to crash and we have that familiar file

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not found error. So we know how to deal with that.

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We need to catch this exception. The exception occurs right here.

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It happens when we try to get hold of this piece of data

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which may or may not exist. So if it does not exist,

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so we're going to catch this except file not found error. Well,

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in that case, we're going to be using the original data

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which comes from the french_words.csv. So we'll say pandas.

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read_csv

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and then we're going to read this file, data/french_words.csv.

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So this is always going to be there because it's preloaded with our project.

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But if we do manage to find our words_to_learn.csv,

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then that means this program has been run before and we've removed some of the

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words we already know. So we can catch that with an else statement and we can say,

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well, in this case,

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we're going to set a global variable called to_learn

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which starts out as an empty dictionary.

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And we set it to the data that comes from this CSV.

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However, if that file was not found,

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then this to_learn is going to be set to the original data.to_dict

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and we're going to orient according to records as well.

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Okay.

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Now, when we run our code, you can see we have no errors.

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And the first time that it runs,

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it's going to pick from our french_words.csv. Now,

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once I've started saying I've learned this, I've learned this,

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I've learned this, then it's going to generate a words_to_learn.csv.

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And the next time I run this code,

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it's gonna start using that words_to_learn.csv and start where I left off.

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Now, there is one slight weird bug to this.

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When you take a look at the words_to_learn.csv,

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it adds the record number to the first column

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every single time I run the code. So if I run this code again,

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you can see now I have three columns of all of the records.

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So basically when we read from this particular CSV,

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we generate a data frame. And when I read from that data frame,

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so let's delete this and run our code again,

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you can see that pandas is automatically added in these record numbers.

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So that gets then added back into our words_to_learn.csv when it saves it into

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the file. If we want to get rid of these record numbers,

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all we have to do is when we save it to the CSV,

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we can set a property called index to false. This way

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it just doesn't add the index numbers to our newly created list

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and now if I rerun this code,

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you can see that our words_to_learn.csv

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doesn't actually include an index. It only includes the actual records or

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the actual words and their English translations.

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That's

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basically it. That's all the solutions to our capstone project.

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And you've now built a fully fleshed flashcard that you can use to learn

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languages.

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So you could have the front with whatever language you want, and the back with

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English translations, or you can use it to learn Programming facts.

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You could have the front with a Programming word and the back as the meaning of

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the Programming word.

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You could use it to study History or Geography.

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And this program is going to help you manage all the things that you don't

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remember and keep showing it to you until you do. Have fun modifying this

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flashcard app and I hope it will be helpful in your studies as well.

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If you've built something particularly interesting, again,

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be sure to share with us in the Q/A so that we can all admire and

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congratulate you on your hard work.