1 00:00:05,200 --> 00:00:10,363 Alright, so back to our meal planner code. It's time to make these dictionaries work together. 2 00:00:10,363 --> 00:00:16,261 At the moment, our code creates the display_menu dictionary, and uses it to print the menu. 3 00:00:16,261 --> 00:00:20,560 Now we're getting input from the user, but only checking for zero at the moment, and you can 4 00:00:20,560 --> 00:00:26,320 see that's on line 17. If the user enters zero, we break out of the loop. If they enter something else, 5 00:00:26,320 --> 00:00:34,183 we'll start by making sure it's a valid choice. So we'll come down here and start typing on line 19. 6 00:00:34,183 --> 00:00:43,638 We'll put an elif here - that's obviously for our if - and we're going to do a choice in display_dict colon. 7 00:00:43,638 --> 00:00:46,880 I'll just move this up a bit, so we're not affecting the subtitles. 8 00:00:46,880 --> 00:00:55,960 Then we're going to put selected_item is equal to display_dict square brackets choice. 9 00:00:55,960 --> 00:01:02,632 Then we're going to print it out, so print parentheses f double quotes You have selected. 10 00:01:02,632 --> 00:01:08,666 Then in left and right curly braces, selected_item, and finish the line. 11 00:01:08,666 --> 00:01:14,320 Alright, so the condition on line 19, checks that the user's input is a valid key 12 00:01:14,320 --> 00:01:21,181 in the display_dict dictionary. If it is, we can proceed to check the ingredients, and we'll do that next. 13 00:01:21,181 --> 00:01:26,640 Line 20 uses the key to get a value from the display_dict dictionary, 14 00:01:26,640 --> 00:01:31,520 and we're printing that value out in the message on line 21. That's useful confirmation for the user, 15 00:01:31,520 --> 00:01:37,613 and also lets us see what's happening. Alright, so let's run the program. 16 00:01:38,560 --> 00:01:44,878 Alright, so I fancy an egg sandwich. I'm going to select option four. 17 00:01:46,560 --> 00:01:50,320 An egg sandwich appears, as you can see, in the message, You've selected Egg sandwich, 18 00:01:50,320 --> 00:01:55,680 so that's working well. Egg sandwich is a value in our display_dict dictionary. 19 00:01:55,680 --> 00:02:02,160 It's also a key in the recipes dictionary. I'm going to switch back to contents.py over here. 20 00:02:02,160 --> 00:02:10,320 We'll end the program, and you can see there's the key, on line 50. Intellij has a useful feature 21 00:02:10,320 --> 00:02:14,880 that can make it easier to work with large data structures. So notice that each of the 22 00:02:14,880 --> 00:02:20,960 recipe keys has a little minus button, just on the margin. Clicking that button collapses the entry. 23 00:02:20,960 --> 00:02:25,843 The button then changes to a little plus, which will expand the entry again. 24 00:02:34,320 --> 00:02:40,240 Alrighty. So you can see I've collapsed each of the keys in our recipes dictionary, to remove some of 25 00:02:40,240 --> 00:02:45,480 the clutter from the screen. Now the line numbers in the margin remain correct. We've still got egg sandwich, 26 00:02:45,480 --> 00:02:50,640 as you can see there on line 50, with beans on toast appearing on line 55. We're just hiding 27 00:02:50,640 --> 00:02:57,190 the details, to make it easier to read the keys. Alright, so the value we chose from the display_dict dictionary 28 00:02:57,190 --> 00:03:02,240 can be used to get the list of ingredients from this recipes dictionary. 29 00:03:02,240 --> 00:03:09,562 So I'm going to expand egg sandwich again, and there's the ingredients we need on lines 51 through 53. 30 00:03:09,562 --> 00:03:15,000 So let's get that list in our code. We're going to switch back to meal_planner, 31 00:03:15,000 --> 00:03:21,200 and we're going to print that list out. So let's come down here, and it's still within our elif block. 32 00:03:21,200 --> 00:03:25,777 After the print, we're going to retrieve the list from the recipes dictionary. What I'll do is, 33 00:03:25,777 --> 00:03:30,173 I'll print it to check what we're getting, but we'll do something more interesting with it soon. 34 00:03:30,173 --> 00:03:36,271 So on the next line I'm going to start with print parentheses checking ingredients 35 00:03:37,520 --> 00:03:43,787 dot dot dot, and then on the next line, we're going to type ingredients 36 00:03:43,787 --> 00:03:49,683 is equal to recipes, left square bracket, then selected_item. 37 00:03:49,683 --> 00:03:55,177 And just to make sure, as I mentioned, we're going to print ingredients. 38 00:03:56,080 --> 00:04:00,630 Alright. Now I did actually stop the program, so I'm going to run it again. 39 00:04:01,360 --> 00:04:07,120 I'm going to choose option 4 again. So after the You've selected egg sandwich message, we've 40 00:04:07,120 --> 00:04:11,760 got checking ingredients, and we can also now see our list of ingredients. So make sure you 41 00:04:11,760 --> 00:04:16,240 understand what's happening here. The next step is to link in the pantry dictionary, and if you 42 00:04:16,240 --> 00:04:20,560 don't understand this bit, you'll really struggle with the next step. Now this is something that 43 00:04:20,560 --> 00:04:27,073 students have found confusing, so I'm going to labour the point here. I'll use some slides to review what's happening here. 44 00:04:27,073 --> 00:04:34,896 So we saw this in the last video. We use enumerate to take the keys from the recipe's dictionary 45 00:04:34,896 --> 00:04:39,600 and produce a new dictionary called display_dict. 46 00:04:39,840 --> 00:04:45,280 That lets us display the keys, with an option number that the user can use to select a recipe. 47 00:04:46,080 --> 00:04:49,480 Now let's see what happens when the user makes a selection. 48 00:04:50,640 --> 00:04:55,040 I've used option 4 for this example, because that's the option I used when we ran the program earlier. 49 00:04:55,760 --> 00:05:00,640 Option four is the egg sandwich, and we retrieve that value from the display_dict 50 00:05:00,640 --> 00:05:07,280 dictionary. We can then use that value to retrieve the ingredients list from recipes. 51 00:05:07,280 --> 00:05:12,640 That's the blue arrow on the slide. When we have a value from the display_dict dictionary, 52 00:05:12,640 --> 00:05:21,120 we can use it to index into the recipes dictionary. Because all the values on the right were produced 53 00:05:21,120 --> 00:05:26,000 from the keys on the left, we know they'll work as indexes into the recipe's dictionary. 54 00:05:26,640 --> 00:05:32,560 The pale red arrow shows where Egg sandwich came from. We didn't retype those strings, so we don't 55 00:05:32,560 --> 00:05:38,560 have to worry about things like typing errors, missing spaces or incorrect capitalization. 56 00:05:38,560 --> 00:05:45,440 So spend some time making sure you understand this, before moving on to the next video.