1 00:00:04,710 --> 00:00:06,809 Alright, so moving on now with the 2 00:00:06,809 --> 00:00:08,519 completion of the challenge introduced 3 00:00:08,519 --> 00:00:11,430 in the last video, it's now time to time 4 00:00:11,430 --> 00:00:13,260 the functions. So to start off doing that 5 00:00:13,260 --> 00:00:15,750 we need to firstly import the timeit 6 00:00:15,750 --> 00:00:18,480 module. Let's go ahead and do that - 7 00:00:18,480 --> 00:00:21,780 it should be on line 1, above the text 8 00:00:21,780 --> 00:00:23,420 definition. So it's going to be import 9 00:00:23,420 --> 00:00:26,640 timeit. Now as I said in 10 00:00:26,640 --> 00:00:28,650 the previous video, I'm going to do it 11 00:00:28,650 --> 00:00:30,690 slightly differently. So the challenge 12 00:00:30,690 --> 00:00:32,610 was to time the code, and if you've added 13 00:00:32,610 --> 00:00:34,109 code, something 14 00:00:34,109 --> 00:00:36,870 along the lines of this; so 15 00:00:36,870 --> 00:00:40,170 something like print parentheses timeit 16 00:00:40,170 --> 00:00:43,820 dot timeit parentheses comp 17 00:00:43,820 --> 00:00:46,770 underscore caps parentheses double quote 18 00:00:46,770 --> 00:00:49,590 comma. Then do something like setup 19 00:00:49,590 --> 00:00:54,469 equals, double quotes again, from 20 00:00:54,469 --> 00:00:59,879 map underscore intro import comp underscore 21 00:00:59,879 --> 00:01:06,390 caps, then number equals 10,000, 22 00:01:06,390 --> 00:01:08,940 or actually make it 100,000. So if you did 23 00:01:08,940 --> 00:01:10,950 something like that, or put the functions 24 00:01:10,950 --> 00:01:12,840 inside the strings, then that's fine. You don't 25 00:01:12,840 --> 00:01:14,130 need to watch me do something that we've 26 00:01:14,130 --> 00:01:15,720 already covered, and we've looked at the 27 00:01:15,720 --> 00:01:17,460 various ways that you can provide the 28 00:01:17,460 --> 00:01:19,830 correct environment to timeit. However, 29 00:01:19,830 --> 00:01:21,600 there is another method we can use, 30 00:01:21,600 --> 00:01:23,820 and you have to read the documentation very 31 00:01:23,820 --> 00:01:26,700 carefully to work it out. So let's have a 32 00:01:26,700 --> 00:01:28,080 look at the documentation and you'll see 33 00:01:28,080 --> 00:01:30,090 what I mean. So we'll just bring it up in 34 00:01:30,090 --> 00:01:36,000 a browser. The bit I'm interested in is down 35 00:01:36,000 --> 00:01:37,350 here, under 28.2.2, 36 00:01:37,350 --> 00:01:40,740 Python Interface. Now in the 37 00:01:40,740 --> 00:01:43,470 description of timeit, it says that this 38 00:01:43,470 --> 00:01:45,750 method will create a timer instance with 39 00:01:45,750 --> 00:01:48,090 the given argument, setup code and timer 40 00:01:48,090 --> 00:01:50,610 function, and run its timeit parenthesis 41 00:01:50,610 --> 00:01:52,799 method. Now these three functions are 42 00:01:52,799 --> 00:01:55,110 convenience functions, to save us from 43 00:01:55,110 --> 00:01:56,670 having to type, or create rather, 44 00:01:56,670 --> 00:01:59,340 instances of the timeit class. That's 45 00:01:59,340 --> 00:02:01,049 the three there that you can see, one two 46 00:02:01,049 --> 00:02:03,540 three. Now as you can see, the 47 00:02:03,540 --> 00:02:06,060 documentation is quite sparse. If you 48 00:02:06,060 --> 00:02:07,649 want to know more, we should look at 49 00:02:07,649 --> 00:02:09,329 that timer class which you can see down here, 50 00:02:09,329 --> 00:02:11,599 immediately below those functions. 51 00:02:11,599 --> 00:02:14,249 And there you'll find a more detailed 52 00:02:14,249 --> 00:02:16,439 description of what the convenience 53 00:02:16,439 --> 00:02:18,360 functions are doing for us and 54 00:02:18,360 --> 00:02:19,710 it's worth reading the timer class 55 00:02:19,710 --> 00:02:22,440 documentation carefully. Now if we scroll 56 00:02:22,440 --> 00:02:24,930 down and have a look, the last paragraph for 57 00:02:24,930 --> 00:02:26,190 the class itself, just before the 58 00:02:26,190 --> 00:02:27,600 description of the timeit method down 59 00:02:27,600 --> 00:02:29,550 here, is interesting because it says 60 00:02:29,550 --> 00:02:32,040 that the statement and setup parameters can 61 00:02:32,040 --> 00:02:33,810 also take objects that are callable 62 00:02:33,810 --> 00:02:36,660 without arguments. Objects that are 63 00:02:36,660 --> 00:02:39,690 callable, basically, mean functions. There 64 00:02:39,690 --> 00:02:41,430 are other callable objects in Python, 65 00:02:41,430 --> 00:02:43,500 classes for example, and they're called 66 00:02:43,500 --> 00:02:45,990 to create a class instance. Alright so 67 00:02:45,990 --> 00:02:48,150 what that sentence means is that we can 68 00:02:48,150 --> 00:02:50,190 pass a reference to a function 69 00:02:50,190 --> 00:02:53,490 as the statement to be timed. The function 70 00:02:53,490 --> 00:02:55,110 must not have any parameters, 71 00:02:55,110 --> 00:02:56,550 which becomes obvious when you see the code, 72 00:02:56,550 --> 00:02:58,290 because there's no way to include 73 00:02:58,290 --> 00:03:01,380 arguments in a function reference. Now 74 00:03:01,380 --> 00:03:02,520 that'll make more sense when you've seen 75 00:03:02,520 --> 00:03:04,530 the code. So what I'm going to do is go back to 76 00:03:04,530 --> 00:03:07,080 IntelliJ. Now we'll just run this to make 77 00:03:07,080 --> 00:03:09,270 sure that it would have worked. You 78 00:03:09,270 --> 00:03:10,920 can see we did get a timing result there, so 79 00:03:10,920 --> 00:03:12,840 that's working. But for now what I'll do 80 00:03:12,840 --> 00:03:16,380 is, I'll comment that out. We're going to 81 00:03:16,380 --> 00:03:19,620 replace it by adding the code 82 00:03:19,620 --> 00:03:23,370 to timeout for functions. So I'll start off 83 00:03:23,370 --> 00:03:26,370 with print, then it's going to be 84 00:03:26,370 --> 00:03:29,670 parentheses timeit dot timeit. Then we're 85 00:03:29,670 --> 00:03:33,110 going to do comp underscore caps comma 86 00:03:33,110 --> 00:03:37,320 space number equals 100,000 and then the 87 00:03:37,320 --> 00:03:39,630 two closing parentheses. I'm going to 88 00:03:39,630 --> 00:03:43,620 take a copy of that line, and we'll actually 89 00:03:43,620 --> 00:03:45,090 call the other functions as well. So I've 90 00:03:45,090 --> 00:03:47,660 got comp underscore caps. The second one 91 00:03:47,660 --> 00:03:52,290 will be map underscore caps, the third 92 00:03:52,290 --> 00:03:57,540 one is comp underscore words and the 93 00:03:57,540 --> 00:04:03,480 last one will be map underscore words. So 94 00:04:03,480 --> 00:04:05,400 you can see that's a lot simpler. There's 95 00:04:05,400 --> 00:04:07,200 no setup argument needed for one thing, 96 00:04:07,200 --> 00:04:08,880 when you pass a function reference to 97 00:04:08,880 --> 00:04:11,489 timeit. In fact it looks suspiciously 98 00:04:11,489 --> 00:04:14,400 easy. So the real question here is, 99 00:04:14,400 --> 00:04:18,988 does it work? Let's run the program, 100 00:04:18,988 --> 00:04:20,970 and then you can see the timings there for our 101 00:04:20,970 --> 00:04:22,370 four functions, so clearly it's working. 102 00:04:22,370 --> 00:04:24,870 Now before we go into detail and look at 103 00:04:24,870 --> 00:04:26,760 those times, let's review what we did 104 00:04:26,760 --> 00:04:28,680 here. So we wrapped each of our code 105 00:04:28,680 --> 00:04:31,530 blocks up in a function definition. You 106 00:04:31,530 --> 00:04:32,340 either have to do that, 107 00:04:32,340 --> 00:04:34,889 or turn them into a string in order to 108 00:04:34,889 --> 00:04:37,290 time them. Next we passed a reference to 109 00:04:37,290 --> 00:04:39,720 each of the functions, to the timeit dot timeit 110 00:04:39,720 --> 00:04:41,850 function. Note that again, we're not 111 00:04:41,850 --> 00:04:43,800 using parentheses. We're passing a 112 00:04:43,800 --> 00:04:46,199 reference to the function, not a function 113 00:04:46,199 --> 00:04:48,690 call. Now if you try to call the function, 114 00:04:48,690 --> 00:04:51,330 you'll get an error. So if we replace 115 00:04:51,330 --> 00:04:53,130 the first reference there - the comp underscore 116 00:04:53,130 --> 00:04:56,280 caps - and add parentheses, try and 117 00:04:56,280 --> 00:04:58,770 run that, you'll get an error. And that's 118 00:04:58,770 --> 00:05:00,540 because when the documentation refers 119 00:05:00,540 --> 00:05:02,990 to a callable, it means the function itself 120 00:05:02,990 --> 00:05:05,660 not the result of calling the function. 121 00:05:05,660 --> 00:05:08,700 There are other ways to use timeit 122 00:05:08,700 --> 00:05:10,590 and now you know how it works, try Googling 123 00:05:10,590 --> 00:05:12,479 for other examples. We'll come back to 124 00:05:12,479 --> 00:05:14,160 this later when we've looked at 125 00:05:14,160 --> 00:05:16,080 decorators. For now, I'm going to remove 126 00:05:16,080 --> 00:05:18,810 the bogus parentheses and run the 127 00:05:18,810 --> 00:05:21,000 program again, so that we can review 128 00:05:21,000 --> 00:05:22,260 those timings in the bottom left hand 129 00:05:22,260 --> 00:05:24,600 corner of the screen. There's not a great 130 00:05:24,600 --> 00:05:26,550 deal of difference, but after running the 131 00:05:26,550 --> 00:05:30,150 program a few times, you can see that 132 00:05:30,150 --> 00:05:32,039 after running the program a few times, 133 00:05:32,039 --> 00:05:34,650 as I'm doing now, there's not really a great 134 00:05:34,650 --> 00:05:35,550 deal of difference but the 135 00:05:35,550 --> 00:05:37,800 comprehensions appear to be slightly 136 00:05:37,800 --> 00:05:40,860 faster than using a map. Now it's 137 00:05:40,860 --> 00:05:42,389 interesting because when I actually ran 138 00:05:42,389 --> 00:05:45,750 this on my iMac Pro, which has got many 139 00:05:45,750 --> 00:05:48,720 cores, the first time that function - the 140 00:05:48,720 --> 00:05:50,729 map underscore, the map underscore 141 00:05:50,729 --> 00:05:53,370 caps function - appeared to be faster. But 142 00:05:53,370 --> 00:05:54,990 as you can see here on this Mac, and most 143 00:05:54,990 --> 00:05:57,090 probably on most computers that you run 144 00:05:57,090 --> 00:05:58,770 this, you should find that comprehensions 145 00:05:58,770 --> 00:06:01,260 version is slightly faster. So in other 146 00:06:01,260 --> 00:06:02,400 words, the comp_caps 147 00:06:02,400 --> 00:06:04,380 function and the comp underscore 148 00:06:04,380 --> 00:06:05,820 words function should generally 149 00:06:05,820 --> 00:06:07,169 be faster for you, and you can see that's 150 00:06:07,169 --> 00:06:08,550 the case, in the code that I'm executing 151 00:06:08,550 --> 00:06:10,440 here because I'm on a different Mac 152 00:06:10,440 --> 00:06:13,440 computer now. So I'll run that again. You 153 00:06:13,440 --> 00:06:15,150 can see, we're consistently finding that the 154 00:06:15,150 --> 00:06:17,310 comprehensions version is slightly 155 00:06:17,310 --> 00:06:21,450 faster than the map version. The timing 156 00:06:21,450 --> 00:06:23,190 for the comprehension is the first value 157 00:06:23,190 --> 00:06:25,080 in each pair, and the value for 158 00:06:25,080 --> 00:06:26,880 com underscore caps and map underscore 159 00:06:26,880 --> 00:06:28,950 caps, the first pair of timings was 160 00:06:28,950 --> 00:06:31,289 pretty inconclusive, when we tried to run 161 00:06:31,289 --> 00:06:33,169 it on a 16 gigabyte Linux system. 162 00:06:33,169 --> 00:06:34,740 Capitalizing the words is more 163 00:06:34,740 --> 00:06:36,150 consistent, though, with the comprehension 164 00:06:36,150 --> 00:06:38,550 working out slightly faster, but you can 165 00:06:38,550 --> 00:06:40,289 see in my case here though, in both 166 00:06:40,289 --> 00:06:41,580 scenarios I've run this a number of 167 00:06:41,580 --> 00:06:43,500 times, even though the results are close, 168 00:06:43,500 --> 00:06:45,690 on every single occasion we're finding the 169 00:06:45,690 --> 00:06:46,169 comprehension 170 00:06:46,169 --> 00:06:49,259 version is beating out the map version. 171 00:06:49,259 --> 00:06:51,599 In other words, it's faster. If you come 172 00:06:51,599 --> 00:06:53,129 across map being used in code that you 173 00:06:53,129 --> 00:06:54,449 have to work with, you now know what 174 00:06:54,449 --> 00:06:56,340 it's doing. When running your own code, 175 00:06:56,340 --> 00:06:58,379 there's little reason to use a map, 176 00:06:58,379 --> 00:07:00,629 though, instead of a comprehension. So 177 00:07:00,629 --> 00:07:02,099 I'm going to stop the video here, and in 178 00:07:02,099 --> 00:07:03,270 the next one we'll start looking at the 179 00:07:03,270 --> 00:07:05,879 filter function. So I'll see you in the 180 00:07:05,879 --> 00:07:08,330 next video.