1 00:00:05,400 --> 00:00:09,730 In this video, we're gonna start talking about string formating in Python. 2 00:00:09,730 --> 00:00:13,210 Now when printing strings and numbers, it's often gonna be convenient to display 3 00:00:13,210 --> 00:00:18,470 both strings and numbers at the same time, in a single call to print. 4 00:00:18,470 --> 00:00:21,250 So, for example you might want to print a description of what the value 5 00:00:21,250 --> 00:00:23,050 is before the value itself. 6 00:00:23,050 --> 00:00:27,050 As you saw, in a previous video, numbers cannot be canonated or 7 00:00:27,050 --> 00:00:30,310 appended with strings using the plus operator, because 8 00:00:30,310 --> 00:00:33,800 the presence of that number instructs Python to actually to attempt addition. 9 00:00:33,800 --> 00:00:37,600 And we saw that actually crashes Python, because it can't figure out what to do. 10 00:00:37,600 --> 00:00:40,560 So there are a couple of, different approaches to doing this. 11 00:00:40,560 --> 00:00:43,770 So in this video I'm going to go through and actually show you some of those. 12 00:00:43,770 --> 00:00:47,720 So as you can see on the screen, I have created a new project. 13 00:00:47,720 --> 00:00:50,920 A Python project in IntelliJ called string formating. 14 00:00:50,920 --> 00:00:55,940 I also created a Python file using the new command in IntelliJ so 15 00:00:55,940 --> 00:00:58,490 that we can actually start typing our code in. 16 00:00:58,490 --> 00:01:01,330 So lets look at one way to actually do what I suggested, 17 00:01:01,330 --> 00:01:06,260 which is to actually display a string and a number in the one print statement. 18 00:01:06,260 --> 00:01:10,030 We're gonna use something called the string function, 19 00:01:10,030 --> 00:01:11,580 or str as it's correctly known. 20 00:01:11,580 --> 00:01:13,400 So let's use that now. 21 00:01:13,400 --> 00:01:15,210 Gonna type age = 24. 22 00:01:15,210 --> 00:01:19,900 And I'm gonna do printMy age 23 00:01:19,900 --> 00:01:24,180 is +, now I'm gonna do it the old way we 24 00:01:24,180 --> 00:01:27,130 established in a previous video didn't work just to recap. 25 00:01:27,130 --> 00:01:29,990 So that method will actually result in Python crashing. 26 00:01:29,990 --> 00:01:31,900 So you can see on the right hand side there, and 27 00:01:31,900 --> 00:01:36,690 the reason it's crashing is it's actually trying to concatenate or append a number. 28 00:01:36,690 --> 00:01:39,330 We know that age is a number because of this line here and 29 00:01:39,330 --> 00:01:43,060 line two to a string, which of course is something in double quotes. 30 00:01:43,060 --> 00:01:44,380 We can use a method, 31 00:01:44,380 --> 00:01:48,370 which is something that's brought into Python called the STR method. 32 00:01:49,500 --> 00:01:53,640 And type STR and put a bracket around the age variable, like so. 33 00:01:53,640 --> 00:01:55,370 And effectively what that is doing, 34 00:01:55,370 --> 00:01:59,060 that line there is actually converting what's in the brackets to a string. 35 00:01:59,060 --> 00:02:02,350 So consequently when we run that, we no longer get an error and 36 00:02:02,350 --> 00:02:05,610 we actually get the correct result, my age is 24 years. 37 00:02:05,610 --> 00:02:10,509 So while other languages such as Java will do this for you automatically, Java would 38 00:02:10,509 --> 00:02:13,820 not have crashed in that scenario I showed you on the screen where Python did. 39 00:02:13,820 --> 00:02:14,710 In Python, 40 00:02:14,710 --> 00:02:17,860 we actually need to do it specifically and this is one way of doing it. 41 00:02:17,860 --> 00:02:21,070 Now, you can probably imagine if you had four, five, 42 00:02:21,070 --> 00:02:25,830 or more numbers to actually print like this that it could quickly rather tedious 43 00:02:25,830 --> 00:02:27,590 to having to type that every time. 44 00:02:27,590 --> 00:02:31,070 I'm trying to coerce every variable using the STR method. 45 00:02:31,070 --> 00:02:34,830 And fortunately for us, Python actually provides a much better mechanism. 46 00:02:34,830 --> 00:02:38,370 Now what I'm gonna do is, I'm gonna show you something in Python called replacement 47 00:02:38,370 --> 00:02:41,600 fields and this is gonna be a way that makes it a lot easier to make changes like 48 00:02:41,600 --> 00:02:44,850 this, when your dealing with multiple numbers on the one line. 49 00:02:44,850 --> 00:02:47,060 We're gonna do something called replacement fields. 50 00:02:47,060 --> 00:02:50,200 And later on I'm gonna start talking about an old method 51 00:02:50,200 --> 00:02:54,160 which was called a formating operator, and we'll understand why shortly. 52 00:02:54,160 --> 00:02:57,170 But for now, let's just get stuck into showing you how to do this with 53 00:02:57,170 --> 00:02:58,380 a replacement field. 54 00:02:58,380 --> 00:03:01,640 And probably the best way to actually explain it is actually to show 55 00:03:01,640 --> 00:03:02,720 you an example of it. 56 00:03:02,720 --> 00:03:06,260 So in the scenario of printing as we did above we could do 57 00:03:06,260 --> 00:03:09,510 what is equivalent using these string str method. 58 00:03:09,510 --> 00:03:14,540 We can type, My age is, and 59 00:03:14,540 --> 00:03:19,700 notice I put curly brackets and a number, the number zero in between them. 60 00:03:19,700 --> 00:03:24,910 And I've typed years dot, so type .format(age). 61 00:03:24,910 --> 00:03:29,120 So what I've done there, this is called a replacement field and 62 00:03:29,120 --> 00:03:31,740 this is the actual replacement for this part here. 63 00:03:31,740 --> 00:03:36,620 So it's the syntax of it is a curly brace at the start, 64 00:03:36,620 --> 00:03:39,720 a number in the middle and another curly brace to actually end it. 65 00:03:39,720 --> 00:03:41,800 And that number, which we'll talk about more shortly, 66 00:03:41,800 --> 00:03:44,780 comes into play when we're actually dealing with multiple parameters. 67 00:03:44,780 --> 00:03:46,140 But we'll talk more about that in a minute. 68 00:03:46,140 --> 00:03:47,620 But now let's just run this example, 69 00:03:47,620 --> 00:03:50,030 and we should get exactly the same result as we got before. 70 00:03:50,030 --> 00:03:53,630 Now it doesn't look to be a particularly better way of doing things at the moment, 71 00:03:53,630 --> 00:03:56,120 but where it really starts coming in handy, 72 00:03:56,120 --> 00:03:58,620 is if we've actually got a lot of data and a lot of parameters. 73 00:03:58,620 --> 00:04:02,160 So what i'm gonna do is I'm gonna paste in a bit of code here and 74 00:04:02,160 --> 00:04:04,610 I'm going to just actually make it so it goes up to two lines so 75 00:04:04,610 --> 00:04:05,930 we can actually see it a bit better. 76 00:04:08,040 --> 00:04:12,860 Like so, I'll just move this over a little bit. 77 00:04:12,860 --> 00:04:15,820 So what we've got is, now we've got one big string as you can see there, 78 00:04:15,820 --> 00:04:17,630 that's just all one big string. 79 00:04:17,630 --> 00:04:20,040 But notice how we've got multiple replacement fields now. 80 00:04:20,040 --> 00:04:23,750 So we've got the zero, the one, the, two, the three, the four, the five, 81 00:04:23,750 --> 00:04:25,120 the six, and the seven. 82 00:04:25,120 --> 00:04:28,160 And in the past, in the previous example we had doc format and 83 00:04:28,160 --> 00:04:31,640 we only had just the one thing, the one bit of information which was age, and 84 00:04:31,640 --> 00:04:35,580 that went automatically into this position here, into have a replacement for zero. 85 00:04:35,580 --> 00:04:39,400 Now, we've actually got a total, if you count them, one, two, three, four, five, 86 00:04:39,400 --> 00:04:40,800 six, seven, eight. 87 00:04:40,800 --> 00:04:44,820 And they're actually numbered from zero to seven within the string. 88 00:04:44,820 --> 00:04:46,210 So, what's gonna happen here is, 89 00:04:46,210 --> 00:04:50,500 each one of these is going to be matched up into the particular placement fields. 90 00:04:50,500 --> 00:04:52,780 So, 31 should go into where it's got zero. 91 00:04:52,780 --> 00:04:56,800 The replacement through zero generate into number one, march into number two, 92 00:04:56,800 --> 00:04:57,440 and so on. 93 00:04:57,440 --> 00:05:01,500 And when we actually run this, we should actually see that. 94 00:05:01,500 --> 00:05:03,920 We're gonna open this out so we can see the result. 95 00:05:03,920 --> 00:05:08,000 There are 31 days in January, March, May, July, August, October, December. 96 00:05:08,000 --> 00:05:13,240 So I can see what happened, it actually took those values It took the values in 97 00:05:13,240 --> 00:05:17,610 the .format part of this line and actually put them automatically in the right spot. 98 00:05:17,610 --> 00:05:21,840 So that's the concept of a replacement field as you can see, that it does 99 00:05:21,840 --> 00:05:25,330 really make it a lot easier from the point of view of putting your data together, 100 00:05:25,330 --> 00:05:28,720 cuz we're putting all of the data that we want outputted in the one place. 101 00:05:28,720 --> 00:05:32,000 We're not having to put a bid here like putting your plus str and 102 00:05:32,000 --> 00:05:34,870 whatever the thing is that you want to actually add to that spot as well. 103 00:05:34,870 --> 00:05:37,650 So it's a lot easier to actually process and work with. 104 00:05:37,650 --> 00:05:40,940 That's the one, the replacement fields is the new way of doing things. 105 00:05:40,940 --> 00:05:44,000 And with that said, we can actually make this better as well, 106 00:05:44,000 --> 00:05:46,220 and there's nothing to stop us from using triple quotes. 107 00:05:46,220 --> 00:05:48,220 So for example, I can come back here and 108 00:05:48,220 --> 00:05:52,010 I can paste in some more code and notice I'm using the triple quotes again so 109 00:05:52,010 --> 00:05:54,500 that we're actually dealing with data on multiple lines. 110 00:05:54,500 --> 00:05:59,100 And notice also, I'm reusing a replacement field more than once. 111 00:05:59,100 --> 00:06:02,940 So number two you can see is used multiple times as is number one. 112 00:06:02,940 --> 00:06:06,310 And number zero is also used once as well. 113 00:06:06,310 --> 00:06:10,900 So now when we run that example you can see we've got some data there. 114 00:06:10,900 --> 00:06:11,460 What I might do is, 115 00:06:11,460 --> 00:06:14,220 I might leave this window and then run one window down to the bottom of the screen so 116 00:06:14,220 --> 00:06:15,470 that we can see things a little bit better. 117 00:06:16,740 --> 00:06:17,350 Move to bottom. 118 00:06:17,350 --> 00:06:20,010 It'd be a little bit easier for us to actually read. 119 00:06:20,010 --> 00:06:23,640 So, I'm just going to leave a little bit of space there. 120 00:06:23,640 --> 00:06:26,740 So you can see that it handles quite nicely using the triple quotes 121 00:06:26,740 --> 00:06:31,410 to deal with strings of handling that go over to more than line, 122 00:06:31,410 --> 00:06:33,220 multi-lines in other words. 123 00:06:33,220 --> 00:06:36,790 And obviously compared to the approach at the top of the line three. 124 00:06:36,790 --> 00:06:39,930 That would be a huge long line to actually have to type in if you were doing 125 00:06:39,930 --> 00:06:42,200 like that and it would become quite messy. 126 00:06:42,200 --> 00:06:45,560 So it's a great way to actually replace things and do things in a better way. 127 00:06:45,560 --> 00:06:48,030 And as I said that's being introduced into Python 3. 128 00:06:48,030 --> 00:06:50,530 Now there is another way of doing things and 129 00:06:50,530 --> 00:06:52,640 this is called the string formatting operator. 130 00:06:52,640 --> 00:06:56,300 I mentioned that briefly before and I'm gonna show you how to use it, 131 00:06:56,300 --> 00:07:00,670 despite the fact that it's now being deprecated in Python 3. 132 00:07:00,670 --> 00:07:01,760 And when I say deprecate, 133 00:07:01,760 --> 00:07:06,390 what that actually means is that's a feature that's a part of the program that 134 00:07:06,390 --> 00:07:11,500 actually worked which is now no longer recommended to be used in Python 3. 135 00:07:11,500 --> 00:07:15,570 So it's introduce into Python 2, and it's used extensively in Python 2 code. 136 00:07:15,570 --> 00:07:19,920 And actually that's the reason why I'm going to actually teach you some of this, 137 00:07:19,920 --> 00:07:23,910 because the chances are gonna be high as you move forward learning Python, 138 00:07:23,910 --> 00:07:27,740 that you'll be getting access to Python 2 code. 139 00:07:27,740 --> 00:07:31,960 Because Python 2 has been out there for so long, there's just a huge amount of code 140 00:07:31,960 --> 00:07:35,440 out there and it's kinda pretty important for you to actually see that and 141 00:07:35,440 --> 00:07:38,240 understand how that works because it's a fundamental pile for so 142 00:07:38,240 --> 00:07:39,960 many Python 2 programs. 143 00:07:39,960 --> 00:07:43,020 The other thing you'll be able to do is once you see the way 144 00:07:43,020 --> 00:07:46,170 that this formatting operator works. 145 00:07:46,170 --> 00:07:46,980 If you decide to, 146 00:07:46,980 --> 00:07:51,280 you'll be able to actually convert that to the new replacement field syntax. 147 00:07:51,280 --> 00:07:54,710 So let's just start from the basics, and have a look how it works. 148 00:07:54,710 --> 00:08:00,250 So what I'm going to do is start by typing a formatting operator for 149 00:08:00,250 --> 00:08:01,690 our first example, which was the age. 150 00:08:01,690 --> 00:08:08,060 So print( My age is, and this time we're doing it a little bit different, 151 00:08:08,060 --> 00:08:13,970 we put %D years, And a percent sign again and then whatever we want printed, 152 00:08:13,970 --> 00:08:16,950 in this case, it would be the age variable that we defined in line two. 153 00:08:16,950 --> 00:08:20,210 Now that actually should have been a lowercase d. 154 00:08:20,210 --> 00:08:22,360 Like so, it does actually make a difference. 155 00:08:22,360 --> 00:08:26,180 So now if I run that we should find below all those dates we should get the same 156 00:08:26,180 --> 00:08:29,110 answer that we got when we printed the example from line two. 157 00:08:29,110 --> 00:08:33,090 And you can see that it still does come up and says My age is 24 years. 158 00:08:33,090 --> 00:08:34,950 This again is the old format. 159 00:08:34,950 --> 00:08:38,380 So what actually happened here is you can see 160 00:08:38,380 --> 00:08:41,150 the %d actually got replaced with an integer. 161 00:08:41,150 --> 00:08:44,800 In the integer of course was a value that was in the age variable. 162 00:08:44,800 --> 00:08:50,520 So taking it to the next level, we could actually do something like print, My age 163 00:08:50,520 --> 00:08:54,850 is %d, I can also put %s. 164 00:08:54,850 --> 00:09:01,750 %d, %s let me put a percent again. 165 00:09:01,750 --> 00:09:05,070 This time we put because we've got multiple things that we wanna print. 166 00:09:05,070 --> 00:09:09,800 We can print those in brackets, age, years, 167 00:09:09,800 --> 00:09:15,310 six, months. 168 00:09:15,310 --> 00:09:20,400 All right so, now if we actually run that you can see that it comes up and 169 00:09:20,400 --> 00:09:23,770 says, my age is 24 years, six months. 170 00:09:23,770 --> 00:09:27,340 And you can see what happens is, the first time it's come along, it's what my age is. 171 00:09:27,340 --> 00:09:30,790 It's looked at the variable age and so that needs to be 24 or 172 00:09:30,790 --> 00:09:33,000 in this case I just put a 24 in there. 173 00:09:33,000 --> 00:09:36,810 The next one was a %s, s stands for string. 174 00:09:36,810 --> 00:09:40,310 And so therefore let's put in the value, in this case the years, 175 00:09:40,310 --> 00:09:42,770 which was a literal string that we typed in. 176 00:09:42,770 --> 00:09:47,100 Put it in that spot and you can see that it's done the same thing for the six and 177 00:09:47,100 --> 00:09:48,350 the months as well. 178 00:09:48,350 --> 00:09:52,210 So you can actually have multiple replacements going on 179 00:09:52,210 --> 00:09:53,970 in the one print line, as you can see there. 180 00:09:53,970 --> 00:09:58,160 So replacement's strictly one value at a time, from left to right, and it's got 181 00:09:58,160 --> 00:10:02,810 pretty well none of the flexibility offered by Python 3 replacement fields. 182 00:10:02,810 --> 00:10:06,450 So you should really be focusing on that, replacement fields where possible. 183 00:10:06,450 --> 00:10:09,030 But again, I'm showing you this now just so you can look at 184 00:10:09,030 --> 00:10:12,930 type Python 2 code at some point if you need to, and understand how it works. 185 00:10:12,930 --> 00:10:16,200 Now just to take that a little bit further, let's look at another example and 186 00:10:16,200 --> 00:10:17,110 that's using the for loop. 187 00:10:17,110 --> 00:10:19,640 And we're going to use the for loop one more time, bearing 188 00:10:19,640 --> 00:10:23,450 in mind that we're going to cover the for loop officially in the next section. 189 00:10:23,450 --> 00:10:26,140 But for now, let's just focus on the print statement. 190 00:10:26,140 --> 00:10:31,010 So I'm going to type for, i, in range, 191 00:10:31,010 --> 00:10:36,900 one comma 12, colon, print, number %2d. 192 00:10:36,900 --> 00:10:43,390 And notice I put a number there this time, 193 00:10:43,390 --> 00:10:49,140 squared is %4d and cubed is %4d. 194 00:10:51,560 --> 00:10:56,430 Then for the answers I'm gonna put %i, i, star, star, two, and 195 00:10:56,430 --> 00:11:02,080 it sort of multiply in the previous video the two stars together that indicates 196 00:11:02,080 --> 00:11:08,300 that we're actually doing, we're trying to raise a number to the power of another. 197 00:11:08,300 --> 00:11:12,890 So i ** 2 in this case so i ** 2 is i squared. 198 00:11:12,890 --> 00:11:15,670 And the next one, I'm gonna do i **, or 199 00:11:15,670 --> 00:11:20,970 to the power of, three like so, gives us an answer that's i cubed. 200 00:11:20,970 --> 00:11:24,310 Now if we actually run this and actually have a look at the result 201 00:11:24,310 --> 00:11:28,000 you can see on the output, we've got things nicely formatted. 202 00:11:28,000 --> 00:11:31,170 So the for loop's gone through and done the processing for everything, and 203 00:11:31,170 --> 00:11:34,630 in terms of printing out the numbers, you can see how there's been 204 00:11:34,630 --> 00:11:37,200 a certain amount of width that's been allocated for each section. 205 00:11:37,200 --> 00:11:40,110 So even though it didn't need to use the letter, or 206 00:11:40,110 --> 00:11:44,590 the space before the number 1 We actually put the number in there, we said two, 207 00:11:44,590 --> 00:11:49,110 use up to two, or to allocate two spaces for this var actually working. 208 00:11:49,110 --> 00:11:53,380 Consequently, it allocated that space and just made it blank if it wasn't in use. 209 00:11:53,380 --> 00:11:57,500 And as a result you can see that things are nicely formatted and nicely in order. 210 00:11:57,500 --> 00:12:01,240 And just to confirm that, if we actually remove that and 211 00:12:01,240 --> 00:12:02,620 run this without those numbers in there. 212 00:12:02,620 --> 00:12:06,060 It does still work but it doesn't look anywhere near as neat. 213 00:12:06,060 --> 00:12:09,770 Yes, the first part does up until we've got a number that's greater than nine. 214 00:12:09,770 --> 00:12:13,280 Then you see it starts really losing the actually formatting quite badly. 215 00:12:13,280 --> 00:12:15,570 So I'm gonna put that back to how it was before again. 216 00:12:16,820 --> 00:12:20,080 Run it again so we've got some nice formatting going on and 217 00:12:20,080 --> 00:12:23,150 there's other types of operators you can actually do there. 218 00:12:23,150 --> 00:12:26,310 We've actually put %d, is the one that's for 219 00:12:26,310 --> 00:12:30,670 an integer and you saw %s before, s plus four a string. 220 00:12:30,670 --> 00:12:34,710 Now another thing you can actually do is you can actually specify the precision of 221 00:12:34,710 --> 00:12:35,710 a number as well. 222 00:12:35,710 --> 00:12:36,890 So let's go ahead and actually do that. 223 00:12:36,890 --> 00:12:42,080 And the way to do that, and we can talk for example print pi is 224 00:12:42,080 --> 00:12:49,840 approximately %12f. 225 00:12:49,840 --> 00:12:54,740 And if type 22 divided by 7, if you run that, you can 226 00:12:58,750 --> 00:13:02,780 see by default we've got 3.142857. 227 00:13:02,780 --> 00:13:05,180 And the calculation's actually six decimal places wide. 228 00:13:05,180 --> 00:13:06,480 But we can actually request more. 229 00:13:06,480 --> 00:13:08,890 So we could change the format stream, which we'll do now. 230 00:13:08,890 --> 00:13:10,020 Let's change that, say, to 50. 231 00:13:10,020 --> 00:13:16,350 So we'll come here where it's got 12f and we'll change that to 12.50. 232 00:13:16,350 --> 00:13:19,030 So we're saying that we want a lot more precision there. 233 00:13:19,030 --> 00:13:20,340 So if we do that and run that again. 234 00:13:21,450 --> 00:13:24,890 You can see, we've now got a number that literally has 50 decimal points. 235 00:13:24,890 --> 00:13:28,460 So it's far more detailed, far more precise than what the previous one was. 236 00:13:28,460 --> 00:13:31,580 And it's just adding these numbers in the various part of this, 237 00:13:31,580 --> 00:13:35,550 after the percent sign and before the actual type, which signifies and 238 00:13:35,550 --> 00:13:37,650 actually shows where that position is gonna be. 239 00:13:37,650 --> 00:13:39,270 Whether it's gonna be after the decimal point or 240 00:13:39,270 --> 00:13:42,660 whether it's sort of a gap, in the number to make sure that it lines up nicely. 241 00:13:42,660 --> 00:13:47,500 So once again, the thing to keep in mind is that you probably wont be using these 242 00:13:47,500 --> 00:13:50,390 and you shouldn't be using those in Python 3 generally. 243 00:13:50,390 --> 00:13:52,790 And this is the string formating operators I'm talking about, 244 00:13:52,790 --> 00:13:54,430 these with the percent signs. 245 00:13:54,430 --> 00:13:57,360 But it is important to understand them because you almost certainly will 246 00:13:57,360 --> 00:13:59,680 come across them in your Python codes. 247 00:13:59,680 --> 00:14:03,580 And what I've in the screen now, I'm gonna just open a browser and show you, 248 00:14:03,580 --> 00:14:07,840 this page here and there's a link to this page in the actual video itself. 249 00:14:07,840 --> 00:14:11,370 So go to the resources section of this video and you may have to come here and 250 00:14:11,370 --> 00:14:14,250 actually find out more about string formatting operators and 251 00:14:14,250 --> 00:14:17,900 how they apply to the older version or Python version 2. 252 00:14:17,900 --> 00:14:22,830 By getting back to replacement fields, what we've done here we can 253 00:14:22,830 --> 00:14:26,700 pretty well do it identically and more with replacement fields. 254 00:14:26,700 --> 00:14:28,660 So let's try another example. 255 00:14:28,660 --> 00:14:30,210 We're gonna copy the first part. 256 00:14:32,600 --> 00:14:36,290 Like so, and then we're gonna actually change it into, placed with some syntax. 257 00:14:36,290 --> 00:14:39,010 So I'm gonna type zero which we did before, but 258 00:14:39,010 --> 00:14:40,970 I'm gonna but a colon and a number. 259 00:14:40,970 --> 00:14:42,970 That's gonna be how wide. 260 00:14:42,970 --> 00:14:45,670 We're actually allocating space four. 261 00:14:45,670 --> 00:14:51,000 And likewise I can do 1:4 and 262 00:14:51,000 --> 00:14:54,080 cubed, 2:4. 263 00:14:54,080 --> 00:14:59,310 And instead of the percent which was of course the old way of doing things, 264 00:14:59,310 --> 00:15:01,920 we do type.format as we did earlier and 265 00:15:01,920 --> 00:15:04,610 then we just have the same parameters as they had before. 266 00:15:04,610 --> 00:15:07,900 So when we run that we should get an identical result but 267 00:15:07,900 --> 00:15:10,450 using the new replacement field syntax. 268 00:15:10,450 --> 00:15:13,320 You can see that we have everything nicely formated. 269 00:15:13,320 --> 00:15:15,640 Much as we had with the old approach but 270 00:15:15,640 --> 00:15:18,240 obviously using the new replacement field syntax. 271 00:15:18,240 --> 00:15:20,230 Now, that's what's specifying the width again. 272 00:15:20,230 --> 00:15:23,600 So just to be clear, the first one was the replacement for your number. 273 00:15:23,600 --> 00:15:26,090 And that's which value from 274 00:15:26,090 --> 00:15:30,050 this area after the .format is actually used in which spot. 275 00:15:30,050 --> 00:15:32,260 But the other part after that, of course, was the width. 276 00:15:32,260 --> 00:15:37,110 So colon two meant we allocated a width of 2:4, we allocated a width of four, and 277 00:15:37,110 --> 00:15:39,240 so on and so forth. 278 00:15:39,240 --> 00:15:41,500 Now we can also tidy them up a little bit though. 279 00:15:41,500 --> 00:15:45,540 So what we can do is we can ensure that numbers occupy the same field width but 280 00:15:45,540 --> 00:15:49,750 are left aligned by placing a less than sign after the symbol. 281 00:15:49,750 --> 00:15:53,860 So what we can do there is, come down here, we can leave the first one as it is, 282 00:15:53,860 --> 00:15:58,850 but the second one, with the squared result, we'll put less than four, 283 00:15:58,850 --> 00:16:01,650 down here to two we put less than four there. 284 00:16:01,650 --> 00:16:06,420 If we actually run that, notice how things are now left formatted. 285 00:16:06,420 --> 00:16:08,510 We're still actually allocating the same amount of space. 286 00:16:08,510 --> 00:16:12,450 So things are still lined up but effectively we're left justifying 287 00:16:12,450 --> 00:16:15,330 the numbers so the number will always start from the left hand side. 288 00:16:15,330 --> 00:16:17,330 That's just another way of doing things as well. 289 00:16:17,330 --> 00:16:21,650 And what we could do for the precision example coming back here. 290 00:16:21,650 --> 00:16:23,820 We could actually just copy the Pi result again. 291 00:16:23,820 --> 00:16:28,860 So I'll copy that line, put it down here and we could change that. 292 00:16:28,860 --> 00:16:33,380 Where we had %12f, we could actually delete that change it to replacement 293 00:16:33,380 --> 00:16:38,570 fields format 0:12 to add the precision .50. 294 00:16:38,570 --> 00:16:42,210 So you can see that what you could do with the old format in the new format 295 00:16:42,210 --> 00:16:45,480 using replacement fields quite easily, and change that of course to format. 296 00:16:45,480 --> 00:16:46,840 And there's only the one parameter, 297 00:16:46,840 --> 00:16:50,370 cuz it's only the one replacement field that we're using. 298 00:16:50,370 --> 00:16:53,840 And if we run that, we get the same result with pi, 299 00:16:53,840 --> 00:16:55,430 as you can see down on the bottom of the screen. 300 00:16:57,080 --> 00:17:00,110 So it's quite easy to convert the old style modifiers, 301 00:17:00,110 --> 00:17:04,290 as you saw me do in this video and replace and convert those into the new .format or 302 00:17:04,290 --> 00:17:06,060 the new replacement fields syntax. 303 00:17:06,060 --> 00:17:08,619 The other thing I wanted to mention, was two other things I wanted to mention 304 00:17:08,619 --> 00:17:11,460 before we end this section and I wanted to paste one example in here. 305 00:17:11,460 --> 00:17:13,800 I'm not sure whether we made it clear enough here, but 306 00:17:13,800 --> 00:17:15,970 we can actually do something like this. 307 00:17:15,970 --> 00:17:19,900 You see that we've used the actual replacement numbers out of order for 308 00:17:19,900 --> 00:17:21,050 the replacement fields. 309 00:17:21,050 --> 00:17:24,079 So it doesn't have to start from zero, one, 310 00:17:24,079 --> 00:17:27,810 two and unlike the actual percentage approach with these modifiers, 311 00:17:27,810 --> 00:17:30,230 we can only use those once, and they have to be in order. 312 00:17:30,230 --> 00:17:32,470 In this case we can reuse them multiple times. 313 00:17:32,470 --> 00:17:36,120 So you can see here that we're actually showing we're using a replacement field, 314 00:17:36,120 --> 00:17:38,540 like number two was used in multiple positions. 315 00:17:38,540 --> 00:17:40,690 That's one of the other reasons to use replacement fields. 316 00:17:40,690 --> 00:17:44,530 And of course if you run it, we'll see that it works quite nicely. 317 00:17:44,530 --> 00:17:45,500 Now just in finishing off, 318 00:17:45,500 --> 00:17:49,400 the other thing to note that in terms of those numbers, keep in mind that 319 00:17:49,400 --> 00:17:52,280 actually the use of numbers in replacement fields are actually optional. 320 00:17:52,280 --> 00:17:57,450 So we can actually do something like this if we prefer And 321 00:17:57,450 --> 00:17:59,980 you can see there I'm going through the same range again, but 322 00:17:59,980 --> 00:18:03,770 notice how I'm not actually inferring, or not actually typing in a number at all. 323 00:18:03,770 --> 00:18:07,210 So what will happen there is that will automatically assume that the first one 324 00:18:07,210 --> 00:18:10,720 you use will be zero, the second one will be one, and the third one will be two. 325 00:18:10,720 --> 00:18:12,290 So if we run that we'll see that. 326 00:18:13,520 --> 00:18:15,720 And you can see we still got the correct results. 327 00:18:16,990 --> 00:18:19,560 And note how the third one, even though we didn't specify a number, 328 00:18:19,560 --> 00:18:21,170 we can still actually control the layout. 329 00:18:21,170 --> 00:18:25,610 But of course in that scenario, what you couldn't do is use the value more than 330 00:18:25,610 --> 00:18:29,100 once, as we used in the example above, because of course we need to 331 00:18:29,100 --> 00:18:32,590 actually specify that number if we aregonna use it more than once. 332 00:18:32,590 --> 00:18:35,540 But in those situations where you don't need to actually use something more than 333 00:18:35,540 --> 00:18:37,630 once, this is probably gonna be ideal for you, and 334 00:18:37,630 --> 00:18:39,640 it's a little bit less to type as well. 335 00:18:39,640 --> 00:18:41,990 Okay, so that's it, that's actually the end of this section, so 336 00:18:41,990 --> 00:18:44,640 we've actually looked at running a simple hello world Python program. 337 00:18:44,640 --> 00:18:47,090 And we talked a little bit about variables, and 338 00:18:47,090 --> 00:18:50,850 of course we mentioned the different types of variables that are built into Python. 339 00:18:50,850 --> 00:18:53,790 Went through discussing number data types, heaps and floats etc., and 340 00:18:53,790 --> 00:18:55,700 then talked about strings. 341 00:18:55,700 --> 00:18:59,350 And we've now seen some basic operations that can be performed on numbers and 342 00:18:59,350 --> 00:19:00,040 strings. 343 00:19:00,040 --> 00:19:02,120 We even talked about operator precedence. 344 00:19:02,120 --> 00:19:06,220 And finally we finished off by slicing using slicing to extract sub-strings, 345 00:19:06,220 --> 00:19:07,820 put string operators on. 346 00:19:07,820 --> 00:19:11,660 And of course, we covered in this video how to actually format strings and 347 00:19:11,660 --> 00:19:13,230 how to print strings and numbers together. 348 00:19:13,230 --> 00:19:14,570 So in the next video what we're gonna do is, 349 00:19:14,570 --> 00:19:17,570 we're gonna start looking at statements that allow us to control the flow 350 00:19:17,570 --> 00:19:21,570 of a program, and also to repeat paths for a program many times. 351 00:19:21,570 --> 00:19:23,890 So, thanks for watching and I'll see you in the next section.