1 00:00:00,830 --> 00:00:09,940 Let's talk about our next data structure and this one is called a dictionary in other languages. 2 00:00:09,940 --> 00:00:15,580 It might be called the hash table maybe map or objects in Python. 3 00:00:15,580 --> 00:00:22,960 We have this idea of dictionary or as Python likes to call it dict have to make sure I pronounce that 4 00:00:22,960 --> 00:00:23,470 properly. 5 00:00:23,470 --> 00:00:29,140 That's a really hard word to say when you're recording and you're repeating it over and over anyway. 6 00:00:29,140 --> 00:00:30,460 Dictionary. 7 00:00:30,460 --> 00:00:31,180 What is it. 8 00:00:31,690 --> 00:00:36,190 Well it's a data type in Python but it's also a data structure. 9 00:00:36,280 --> 00:00:40,770 Remember that I mentioned this idea of data structure when we talked about lists. 10 00:00:40,960 --> 00:00:45,700 There were the first the data structure in Python that we learned. 11 00:00:45,820 --> 00:00:53,770 It's a way for us to organize our data in a form that is has some different pros and cons and how we 12 00:00:53,770 --> 00:00:56,790 access it for example with lists. 13 00:00:56,890 --> 00:00:59,380 We saw that they're easily ordered. 14 00:00:59,380 --> 00:01:05,260 We can access them through indexes like 0 1 we can reverse them we can insert into them. 15 00:01:05,260 --> 00:01:06,990 It was really really nice. 16 00:01:07,000 --> 00:01:08,860 What about dictionaries. 17 00:01:08,860 --> 00:01:17,550 Well let's see what a dictionary looks like a dictionary will look something like this will have a key 18 00:01:18,710 --> 00:01:28,540 and a value then another comma and then another key and another value let's decipher this. 19 00:01:29,170 --> 00:01:37,060 So I'm using curly brackets here which denotes a dictionary and unlike a list we have what we call a 20 00:01:37,060 --> 00:01:39,200 key value pair. 21 00:01:39,280 --> 00:01:47,630 A key is a string for us to grab the value what I mean. 22 00:01:47,630 --> 00:01:55,910 Well in order for us to access any of these values I would go dictionary and then say the key in our 23 00:01:55,910 --> 00:02:01,970 case let's say we want to grab b. we would grab the key and then when we print here the result 24 00:02:04,770 --> 00:02:11,340 we get the value to we're essentially telling the computer Hey I have this variable dictionary remember 25 00:02:11,340 --> 00:02:13,170 I can name this whatever I want. 26 00:02:13,350 --> 00:02:21,240 I have this variable dictionary I want you to go find the key b and this key B if it exists grab me 27 00:02:21,240 --> 00:02:21,810 the value. 28 00:02:21,870 --> 00:02:25,340 So it's going to go into your memory or into the machine's memory. 29 00:02:25,440 --> 00:02:30,480 It's going to find where B is stored in our memory and grab the value. 30 00:02:30,480 --> 00:02:37,750 So in the bookshelf b we have the value to what if we do see which doesn't exist. 31 00:02:37,830 --> 00:02:44,160 If I click Run No I get an error it tells me hey sorry you're looking for key C but I don't really have 32 00:02:44,160 --> 00:02:53,160 that key and this is what a dictionary is a dictionary is an on ordered key value pair what I mean by 33 00:02:53,160 --> 00:02:59,760 that unordered means that they are not right next to each other in memory remember with lists we could 34 00:02:59,760 --> 00:03:07,110 access lists with index of 0 then index of one index of to all those bookshelves or right next to each 35 00:03:07,110 --> 00:03:14,070 other a dictionary on the other hand they're all over the place although I've put a and b here this 36 00:03:14,190 --> 00:03:21,700 might be in one spot a memory in this one in an other spot a memory and if I added let's say x this 37 00:03:21,710 --> 00:03:30,310 will be in another spot in memory and this might not be in order maybe I've written it a B X but when 38 00:03:30,310 --> 00:03:37,540 I actually return the entire dictionary maybe I don't have this in order these are all just scattered 39 00:03:37,570 --> 00:03:44,310 all across our memory as you see here when I receive the dictionary I get these things in order but 40 00:03:44,460 --> 00:03:49,920 that's only because it's small if I had a really really large dictionary I might not have them in order 41 00:03:50,040 --> 00:04:00,060 that I've inserted a so a dictionary is an unordered key value pair and as long as we know the key that 42 00:04:00,060 --> 00:04:06,480 is whatever the key that we're looking for then we just give that and our computer is going to know 43 00:04:06,630 --> 00:04:10,800 hey where in memory to look to grab the values. 44 00:04:10,980 --> 00:04:17,060 Now here's the cool thing about data structures like dictionaries and lists they're containers around 45 00:04:17,300 --> 00:04:17,930 data. 46 00:04:17,930 --> 00:04:18,450 Right. 47 00:04:18,500 --> 00:04:21,510 So this can be anything that we want. 48 00:04:21,620 --> 00:04:30,470 Let's say we want this one to be a list one two three maybe we want this to be a string Hello and maybe 49 00:04:30,500 --> 00:04:36,010 this is a volume value like true that is completely valid. 50 00:04:36,050 --> 00:04:41,990 I can access the a like so and I get the list. 51 00:04:42,050 --> 00:04:44,830 What if I want the second item in the list. 52 00:04:44,840 --> 00:04:47,600 Well I do index of one like this. 53 00:04:49,570 --> 00:04:50,410 And there you go. 54 00:04:50,440 --> 00:04:58,030 I get two and this is the same with lists and you'll see this a lot where if we had a list or let's 55 00:04:58,030 --> 00:05:10,360 call it my list and my list contains a dictionary that has let's say a 1 and you know what. 56 00:05:10,390 --> 00:05:11,840 Let's just copy paste this. 57 00:05:12,040 --> 00:05:16,270 We'll do this so we'll have the first item in the array 58 00:05:19,260 --> 00:05:21,390 like this then comma. 59 00:05:21,510 --> 00:05:32,520 Then another item in the array and this time around this one has four five six so that I can now grab 60 00:05:32,520 --> 00:05:33,450 from my list 61 00:05:37,150 --> 00:05:46,960 first item in the array and then maybe grab the A. 62 00:05:47,220 --> 00:05:48,420 That is the key. 63 00:05:48,660 --> 00:05:53,940 So remember this is a string and then we want to grab let's say the third item. 64 00:05:53,940 --> 00:05:59,250 So we'll go to fight run this. 65 00:05:59,510 --> 00:06:02,280 I should get 3 and 2. 66 00:06:02,290 --> 00:06:03,640 There you go. 67 00:06:03,640 --> 00:06:10,720 Now you might be asking yourself what's the deal with these data structures like why do we need dictionary 68 00:06:10,720 --> 00:06:12,280 why do we need list. 69 00:06:12,280 --> 00:06:16,340 Why can we just have one thing that does everything isn't that simpler. 70 00:06:16,360 --> 00:06:20,130 Think about that because in the next video I'm going to try and answer that question for you.