1 00:00:04,840 --> 00:00:09,370 To see some more of the things we can do with print, what I'll do is create a 2 00:00:09,370 --> 00:00:14,010 new Python file called moreprint.py. 3 00:00:22,580 --> 00:00:27,160 The first thing we're going to do, is print several things out at once. 4 00:00:27,160 --> 00:00:36,160 We'll start by typing name equals double quotes Tim, line two, age equals 10, 5 00:00:36,160 --> 00:00:40,020 then on line four I'm going to type print parentheses, and then within the 6 00:00:40,020 --> 00:00:49,400 parentheses, name comma age comma Python in double quotes and then 2020. 7 00:00:50,280 --> 00:00:54,540 So we've got two variables, and on line four we pass both of them, with a string 8 00:00:54,550 --> 00:01:01,750 literal and an int, to print. And when I run this program now, you can see we get 9 00:01:01,750 --> 00:01:07,090 each object printed out. The function definition had a single parameter, called 10 00:01:07,090 --> 00:01:13,480 *objects. Now the asterisk is often said as star, so we'd actually say 11 00:01:13,480 --> 00:01:17,220 star objects. That means that we can provide several values, and that's what 12 00:01:17,229 --> 00:01:22,899 we've done here, on line four. Now I wouldn't normally use this, when displaying output 13 00:01:22,899 --> 00:01:26,409 to a user of the program. That's because you don't have all the formatting 14 00:01:26,409 --> 00:01:31,719 options that replacement fields provide. For printing diagnostic information, 15 00:01:31,719 --> 00:01:35,770 it is a very quick way to print out the values of several variables. But the main 16 00:01:35,770 --> 00:01:39,639 reason I've done it here, is to show you that a function can take several values, 17 00:01:39,640 --> 00:01:45,680 when that argument is star something, and in this case, it was star objects. 18 00:01:45,680 --> 00:01:50,799 The sep parameter is a keyword argument we talked about in the previous video. If we 19 00:01:50,799 --> 00:01:55,389 want to provide a value for sep, we have to specify its name. Now that's why 20 00:01:55,389 --> 00:01:58,749 they're also called named arguments. So let's have a go at doing that. 21 00:01:58,749 --> 00:02:03,670 So I'm going to duplicate line four and on line 5 now, I'm going to type a comma 22 00:02:03,670 --> 00:02:09,680 after the 2020, and put sep equals, and in double quotes I'm 23 00:02:09,680 --> 00:02:17,360 going to put a comma and a space. Its usual not to put spaces either side of the equal sign, 24 00:02:17,360 --> 00:02:19,860 when passing a keyword argument by the way. 25 00:02:19,860 --> 00:02:24,959 Okay, so we've set sep to a comma, followed by space. Let's run the program 26 00:02:24,959 --> 00:02:30,269 to see the diffearence. Now as you can see, in the second line of output, each value 27 00:02:30,269 --> 00:02:35,280 is separated from the next one with a comma and a space. This can be useful when 28 00:02:35,280 --> 00:02:40,120 writing data to a text file, and we'll be seeing that in a later section. 29 00:02:40,120 --> 00:02:44,880 The separator's only used when you print several things at once, as we've done here. 30 00:02:44,880 --> 00:02:48,380 If you only print a single value - and that includes an f-string or a 31 00:02:48,389 --> 00:02:54,569 string produced using .format(), then the separator won't be printed. The other 32 00:02:54,569 --> 00:02:58,769 keyword argument that we saw in the documentation, was end. Now end is very 33 00:02:58,769 --> 00:03:02,400 useful in loops, so to see this I'm going to go back to our challenge code, 34 00:03:02,400 --> 00:03:10,409 in nospam.py. So I'll run this first, and as you can see, each of the items is 35 00:03:10,409 --> 00:03:14,340 printed on a new line. Now, it would be tidier to have the items for each 36 00:03:14,340 --> 00:03:20,340 meal appearing on one line. Now we can do that by changing the value of end. So to 37 00:03:20,340 --> 00:03:24,280 do that I'm going to make a change to line 22, and before the right parenthesis 38 00:03:24,280 --> 00:03:30,360 I'm going to type comma end equals, and in double quotes, I'm just going to put a space. 39 00:03:30,360 --> 00:03:35,060 Setting end to a space, tells print to print a space after printing, instead 40 00:03:35,060 --> 00:03:41,000 of a newline. Let's run the program now, to see what effect that's had to the output. 41 00:03:41,000 --> 00:03:45,419 You can see, we've now got the items on a single line. Now the print on line 42 00:03:45,419 --> 00:03:50,370 23 is needed, otherwise all the meals would be on the same line. So I'm going 43 00:03:50,370 --> 00:03:57,870 to comment line 23 out, and rerun it, just to confirm what happens. You can see the 44 00:03:57,870 --> 00:04:01,160 items are now all on one line which is, obviously, not what we want. So I'll 45 00:04:01,160 --> 00:04:07,420 undo that and run it again. Alright. Now we can't use sep here, 46 00:04:07,420 --> 00:04:11,920 because we've only passed one object to print - you can see that on line 22. 47 00:04:11,920 --> 00:04:16,779 Remember that the separator's only used between the values we print, when we pass 48 00:04:16,779 --> 00:04:20,589 more than one value to the print function. However, we can still get a 49 00:04:20,589 --> 00:04:24,400 comma between the meal items, by putting a comma in the string that we used for 50 00:04:24,400 --> 00:04:30,060 end, so let's do that. end is now a comma followed by a space, as you can see there. 51 00:04:30,060 --> 00:04:35,280 Let's run the program to make sure the output is what we expect. 52 00:04:35,280 --> 00:04:39,220 That's not bad, but did you expect that extra comma at the end of each line? It's not 53 00:04:39,220 --> 00:04:43,990 actually easy to remove that, with this code. In fact, the most pythonic way to 54 00:04:43,990 --> 00:04:49,960 get that output without a trailing comma, is to use a generator expression. 55 00:05:28,860 --> 00:05:30,430 So what I'm going to do is take a copy 56 00:05:30,430 --> 00:05:37,180 of this file - nospam.py. We're going to call 57 00:05:37,180 --> 00:05:44,700 this one, nospam_gen, so we don't mess up our original code. 58 00:05:44,700 --> 00:05:49,659 So we can replace the loop on the lines 19 to 23, with this generator code that I'm 59 00:05:49,659 --> 00:05:57,360 about to paste in. Alright so there's the code. Let's run this, 60 00:05:58,639 --> 00:06:03,229 and this time we get the items without the trailing comma on the ends of the 61 00:06:03,229 --> 00:06:07,940 lines. So that's pretty cool, and as you can see, that's only three lines of code. 62 00:06:07,940 --> 00:06:12,160 Alright, so I'm not going to discuss that code on line 20, yet. What I will do in 63 00:06:12,160 --> 00:06:16,240 the next few lectures, is talk about some more methods that strings have. 64 00:06:16,240 --> 00:06:22,860 We'll also see what join on line 20, is doing. See you in the next video.