1 00:00:00,630 --> 00:00:06,060 So in the last two lectures, we are able to create our very own RAS nodes, which are able to communicate 2 00:00:06,060 --> 00:00:09,630 with each other using publisher and subscriber Python scripts. 3 00:00:09,900 --> 00:00:14,850 After writing the Python code, we would open a terminal, go into the scripts folder in our package 4 00:00:14,850 --> 00:00:18,750 and run the Python terminal command followed by our script name. 5 00:00:19,080 --> 00:00:21,690 Well, there's a better way to go about doing this. 6 00:00:21,840 --> 00:00:27,300 In this lecture, we will be configuring our package so that we can run our node from any location in 7 00:00:27,300 --> 00:00:28,110 the terminal. 8 00:00:28,470 --> 00:00:34,020 When we created our package earlier in the course, we had to specify the build type which we specified 9 00:00:34,020 --> 00:00:35,370 as amend make. 10 00:00:35,700 --> 00:00:40,890 This tells Ros to compile our package based on instructions specified in our packages. 11 00:00:40,920 --> 00:00:47,360 See make list, text file, see, make list files which are generally used for compiling C and C++ code. 12 00:00:47,370 --> 00:00:50,520 So this may seem unfamiliar to some of you, and that's okay. 13 00:00:50,520 --> 00:00:54,810 Since we will cover what you need to know to help with your ROS development. 14 00:00:54,840 --> 00:00:55,920 Let's get to it. 15 00:00:57,650 --> 00:01:02,450 When we created our package, we had to specify the build type, which we specified as a meant to make. 16 00:01:02,450 --> 00:01:06,740 What we are telling the compiler is that we will compile our package based on instructions specified 17 00:01:06,740 --> 00:01:08,810 in our make list text file. 18 00:01:08,840 --> 00:01:13,880 So let's go ahead and configure our package to include our Python nodes. 19 00:01:13,970 --> 00:01:19,870 In Visual Studio code, I will open up our package XML file and make list text file. 20 00:01:19,880 --> 00:01:23,360 So let's go ahead and configure our package XML file. 21 00:01:23,360 --> 00:01:25,990 I will add build tool dependencies for MNC. 22 00:01:26,000 --> 00:01:27,020 Make and amend. 23 00:01:27,050 --> 00:01:28,520 See make python. 24 00:01:30,400 --> 00:01:33,760 And I will add our RC LP library as a dependency. 25 00:01:39,120 --> 00:01:39,450 All right. 26 00:01:39,480 --> 00:01:44,470 I'll go ahead and save this package on XML file and move on to our make list text file. 27 00:01:44,490 --> 00:01:52,980 Here, I will add our packages for amend c, make python and rcl py using the find packages function. 28 00:01:58,050 --> 00:02:02,700 Now I know this make list text file can seem a little confusing and daunting at first, but trust me, 29 00:02:02,700 --> 00:02:05,850 we'll get used to this as we utilize it throughout the course. 30 00:02:06,000 --> 00:02:09,090 I meant Python needs to be pointed to a python package. 31 00:02:09,090 --> 00:02:14,210 A python package is simply a folder that has a init python file. 32 00:02:14,220 --> 00:02:20,100 In this case, we want our python package to be our scripts folder so I will create a new file in our 33 00:02:20,100 --> 00:02:22,230 scripts folder called underscore. 34 00:02:22,230 --> 00:02:23,790 Underscore in it. 35 00:02:23,790 --> 00:02:26,430 Underscore underscore dot pi. 36 00:02:26,700 --> 00:02:30,900 Now I don't need to put anything in this file so I can just close it. 37 00:02:31,170 --> 00:02:36,480 Now that our scripts folder looks like a Python package, we can configure it by using the meant python 38 00:02:36,480 --> 00:02:40,950 install command followed by the folder name, which is scripts. 39 00:02:42,820 --> 00:02:47,080 Then lastly, we need to specify our individual Python nodes. 40 00:02:47,110 --> 00:02:49,620 We do this with the install function. 41 00:02:49,630 --> 00:02:51,580 Use the programs keyword. 42 00:02:52,660 --> 00:02:55,240 Followed by the location of the script. 43 00:03:00,890 --> 00:03:06,020 And then we set the destination for our workspace to place it. 44 00:03:06,410 --> 00:03:11,140 In this case, we'll need to put it in the lib folder, followed by our package name. 45 00:03:11,150 --> 00:03:17,690 And the last thing in our make list text file should always be this amount package function, so don't 46 00:03:17,690 --> 00:03:22,970 put code below this line as it will not get properly called when we build our project. 47 00:03:23,000 --> 00:03:25,520 Be sure to save this file when you're done editing. 48 00:03:25,640 --> 00:03:28,220 And now there's actually one more thing we need to do. 49 00:03:28,220 --> 00:03:34,490 Since Cement C make is primarily meant to run a C++ code, we have to tell Ros how we want this script 50 00:03:34,490 --> 00:03:35,570 to be executed. 51 00:03:35,720 --> 00:03:41,540 We do this by opening up our Python scripts that we want to run with Ros and then at the top add a Unix 52 00:03:41,540 --> 00:03:46,760 shebang character sequence, which is the pound sign followed by an exclamation mark, and then point 53 00:03:46,760 --> 00:03:49,880 it to our python three environment for Ubuntu. 54 00:03:49,910 --> 00:03:56,690 This will be located at forward slash us r forward slash bin forward slash in v space. 55 00:03:56,690 --> 00:03:57,850 Python three. 56 00:03:57,860 --> 00:04:01,010 We will have to do this for all of our python scripts. 57 00:04:05,490 --> 00:04:09,450 So would that be sure to save the changes you've made to all these files? 58 00:04:09,870 --> 00:04:12,450 And now if we go ahead and open up a terminal. 59 00:04:12,570 --> 00:04:14,040 I'll go ahead and clear the screen. 60 00:04:14,430 --> 00:04:18,780 And now we'll go ahead and change into our workspace directory here. 61 00:04:18,780 --> 00:04:21,240 So I'll go back a few directories. 62 00:04:25,680 --> 00:04:28,290 And now we can run our calc and build command. 63 00:04:32,440 --> 00:04:36,670 Well, and it seems I ran into an error with using the immense python install package. 64 00:04:36,670 --> 00:04:44,320 Command says target may not contain a slash, so I must have accidentally included a slash when I was 65 00:04:44,560 --> 00:04:46,480 implementing the script folder name. 66 00:04:46,480 --> 00:04:49,210 So go ahead and get rid of the slash in this function call. 67 00:04:49,210 --> 00:04:49,870 Save it. 68 00:04:51,040 --> 00:04:55,690 And now if I go ahead and clear the screen and rerun that Culkin build command. 69 00:04:56,640 --> 00:04:58,750 We see it builds successfully. 70 00:04:58,770 --> 00:05:03,240 Once it's built, we can source the setup file in the install directory. 71 00:05:03,390 --> 00:05:09,000 Now we can check that we configured our package properly by using the ROS to package executables command 72 00:05:09,000 --> 00:05:13,470 and we will specify our package, which in this case is Udemy ROS package. 73 00:05:13,740 --> 00:05:18,510 Here we see a list of executables available in these packages, which in this case is our publisher 74 00:05:18,630 --> 00:05:20,730 API and subscriber pie notes. 75 00:05:20,820 --> 00:05:25,590 Now we can run our nodes using the RAS to run command to launch our publisher node. 76 00:05:25,590 --> 00:05:34,380 Just run RAS to run Udemy RAS two package publisher PI and we see our publisher node running as we did 77 00:05:34,380 --> 00:05:36,940 when we ran it using the Python three command. 78 00:05:36,960 --> 00:05:39,580 Just to show you that this works for our subscriber node as well. 79 00:05:39,600 --> 00:05:45,330 I will open a new terminal tab and again I'll have to source that install setup file. 80 00:05:46,560 --> 00:05:51,480 Since this is a new environment and run our subscriber script. 81 00:05:53,570 --> 00:05:58,340 And here we are receiving the messages in our subscriber node that are being published over here by 82 00:05:58,340 --> 00:05:59,520 our publisher Node. 83 00:05:59,540 --> 00:06:01,820 So I can go ahead and stop these with control C. 84 00:06:02,420 --> 00:06:08,330 So here we are able to run our Python scripts using the ROS to run command because we configured our 85 00:06:08,330 --> 00:06:09,140 package. 86 00:06:09,140 --> 00:06:13,220 This way we can distribute the package to other developers and they can easily run the scripts like 87 00:06:13,220 --> 00:06:13,700 so. 88 00:06:14,770 --> 00:06:15,080 OC. 89 00:06:15,100 --> 00:06:21,670 We got our nodes to properly compile by modifying our make lists, text file and packaged XML files. 90 00:06:21,850 --> 00:06:27,970 Most popular ROS packages use C++ so it's good to get you better situated to this way of building ROS 91 00:06:27,970 --> 00:06:32,110 packages so you can understand the format when you use other packages. 92 00:06:32,290 --> 00:06:35,690 But it's worth noting there is another way to compile our package. 93 00:06:35,710 --> 00:06:41,860 There's a second build type called Amend Python, which is generally used if your package is solely 94 00:06:41,860 --> 00:06:43,990 composed of Python scripts. 95 00:06:44,470 --> 00:06:48,940 This will make our package show more resemblance to that of a standard Python package. 96 00:06:49,030 --> 00:06:56,020 But note the downside of this method is it does not allow you to use any C++ nodes in your ROS package. 97 00:06:56,020 --> 00:06:59,560 Should you want to include C++ code later on down the line. 98 00:06:59,890 --> 00:07:03,700 This is one of the reasons why I recommend using the C make build type. 99 00:07:04,120 --> 00:07:09,100 I will go ahead and show you this layout anyway on a new package so that you are aware of it in case 100 00:07:09,100 --> 00:07:11,800 you see other developers using this build type. 101 00:07:13,450 --> 00:07:15,250 So I'll go ahead and clear the screens. 102 00:07:16,270 --> 00:07:21,490 I'll actually close the second terminal and then I'll head over to the source folder of this workspace. 103 00:07:22,810 --> 00:07:23,080 All right. 104 00:07:23,080 --> 00:07:28,090 So here we see our original Udemy Ross two package, which is now configured with our make list text 105 00:07:28,090 --> 00:07:28,670 file. 106 00:07:28,690 --> 00:07:34,600 And now instead, I'm going to create a new package which I will just call my py package and pass the 107 00:07:34,600 --> 00:07:36,310 build type amount python. 108 00:07:40,680 --> 00:07:40,980 All right. 109 00:07:40,980 --> 00:07:44,370 So we see some text, but the terminal and if I open up a file explorer. 110 00:07:47,300 --> 00:07:54,320 We now have our IP package and instead of having RC make list text file configuration, it now has a 111 00:07:54,320 --> 00:07:57,550 Python package, a resource folder, test folder. 112 00:07:57,560 --> 00:08:03,350 We still have a package of XML, but instead of make lists we have a setup config and set up pie files 113 00:08:03,350 --> 00:08:09,530 before we modify our setup py file, let's include our publisher and subscriber code into this new package. 114 00:08:09,530 --> 00:08:14,870 So instead of the scripts directory we will put it into this my py package which already has an init 115 00:08:15,260 --> 00:08:16,280 py file in it. 116 00:08:16,520 --> 00:08:18,230 So open a new window. 117 00:08:25,160 --> 00:08:28,490 And we'll copy these two nodes we just created. 118 00:08:30,190 --> 00:08:34,900 Now I will go ahead and rename these files just so that we can distinguish them. 119 00:08:34,930 --> 00:08:40,150 So go ahead and click on this and you can right click and go to rename or use the F two shortcut. 120 00:08:40,150 --> 00:08:47,830 And I'll just call this publisher to py just so that we can see that there is a difference between where 121 00:08:47,830 --> 00:08:49,270 these files are located. 122 00:08:50,380 --> 00:08:50,680 All right. 123 00:08:50,680 --> 00:08:56,470 So let's get to configuring our new package XML file for this new ROS package. 124 00:08:56,590 --> 00:09:03,250 So now if I head over to source, go over to my PIP package, I can go ahead and configure our new package 125 00:09:03,370 --> 00:09:07,270 XML file to contain exec dependencies for our cl py. 126 00:09:12,790 --> 00:09:14,950 And the standard message is library. 127 00:09:19,170 --> 00:09:20,750 I'll go ahead and save this. 128 00:09:20,760 --> 00:09:24,140 And next we can edit our setup file. 129 00:09:24,150 --> 00:09:26,740 So here we're going to create our node executables. 130 00:09:26,760 --> 00:09:30,630 This is done in the entry points section towards the end of the file. 131 00:09:30,660 --> 00:09:34,560 So within console scripts we will add an entry to the list. 132 00:09:34,680 --> 00:09:36,960 First, I will add our publisher node. 133 00:09:37,150 --> 00:09:38,550 I'll give it an executable name. 134 00:09:38,550 --> 00:09:43,290 In this case, my publisher and I will set it equal to the name of my package. 135 00:09:43,320 --> 00:09:51,630 Dot the same name of our Python script, which is publisher two and then a semi colon and the name of 136 00:09:51,630 --> 00:09:55,530 the function we want to run, which in this case will be our main function. 137 00:09:56,530 --> 00:09:59,380 And we can do the same for our subscriber node. 138 00:10:11,350 --> 00:10:13,810 All right with this, I'll go ahead and save the file. 139 00:10:13,870 --> 00:10:17,010 We'll go back to our terminal and we will rerun our call. 140 00:10:17,020 --> 00:10:19,000 Can build command within the workspace. 141 00:10:19,480 --> 00:10:24,940 Since we only made changes to the new package, we can use the packages select parameter of colon built 142 00:10:24,970 --> 00:10:28,600 to specify to only build that particular package. 143 00:10:28,600 --> 00:10:31,390 Since that's the only package in this case we made changes to. 144 00:10:32,860 --> 00:10:35,500 So here we see set up tools, depreciation warning. 145 00:10:35,500 --> 00:10:40,510 This will be addressed by the Ross community in later Ross distributions, but for now you can just 146 00:10:40,510 --> 00:10:40,840 ignore it. 147 00:10:40,840 --> 00:10:46,210 It's just a warning our workspace has compiled successfully and I can test that by sourcing our install 148 00:10:46,210 --> 00:10:47,500 setup file. 149 00:10:49,150 --> 00:10:53,890 And then trying to run our publisher node from that new my PY package. 150 00:10:54,890 --> 00:10:59,450 So here we see again our publisher node is running and we can do it once more with our subscriber node 151 00:10:59,450 --> 00:10:59,930 below. 152 00:11:04,710 --> 00:11:09,570 And here we see we're receiving our messages just as we were in our other package. 153 00:11:09,570 --> 00:11:13,080 So this is just two ways to go about creating a Ross package. 154 00:11:13,080 --> 00:11:20,550 One is specific to only being able to run Python files, and one allows you to do C++ files along with 155 00:11:20,550 --> 00:11:23,610 the Python scripts like we were doing earlier. 156 00:11:23,610 --> 00:11:29,760 So feel free to use either version either by configuring a make list text file with your particular 157 00:11:29,760 --> 00:11:37,170 scripts or by using the immense Python method and configuring your console scripts in a setup file. 158 00:11:37,170 --> 00:11:43,020 But again, I will refer to the make list text file version using a C build type because that is the 159 00:11:43,020 --> 00:11:46,470 most common build type you will see amongst ROS packages. 160 00:11:48,050 --> 00:11:49,610 Well, congratulations. 161 00:11:49,610 --> 00:11:54,410 You just learned how to configure your workspace in two different ways to run your Python nodes within 162 00:11:54,410 --> 00:11:55,700 your ROS package. 163 00:11:55,730 --> 00:11:57,620 Let's review what we learned. 164 00:11:59,220 --> 00:12:04,650 In this lecture, we learned how to configure our packages so we can run our Python scripts using the 165 00:12:04,650 --> 00:12:08,970 ROS to run command for packages that use the C make build type. 166 00:12:08,970 --> 00:12:15,720 We configured the package xml file by including build tool dependencies for a meant c, make c make 167 00:12:15,720 --> 00:12:18,360 python and rcl py. 168 00:12:18,720 --> 00:12:24,150 Then we configured our to make list text files where we used find package to include the same dependencies. 169 00:12:24,150 --> 00:12:30,390 Then we set our scripts folder as our python package directory by using a mint python install package. 170 00:12:30,720 --> 00:12:34,290 Remember that the folder must have an init script in it. 171 00:12:34,930 --> 00:12:41,800 Then we use the install programs to include each of our scripts and set the destination to lib slash 172 00:12:41,800 --> 00:12:45,730 and the package name which we are able to call with the project name variable. 173 00:12:47,050 --> 00:12:51,910 We configured our Python files by telling the compiler how to run our scripts. 174 00:12:51,910 --> 00:12:58,690 And once we did all of that, we were able to build source and run our python nodes using the ROS to 175 00:12:58,690 --> 00:12:59,680 run command. 176 00:13:00,070 --> 00:13:04,660 We also took a look at how to configure our package XML and setup files. 177 00:13:04,660 --> 00:13:08,810 If you use the omit python as your build type for your package. 178 00:13:08,830 --> 00:13:14,560 So configuring our package XML, we have to include these exec dependencies for RC, LP and any message 179 00:13:14,560 --> 00:13:20,310 types we are using as well as configuring our setup py file which will be created in place of a make 180 00:13:20,380 --> 00:13:26,470 list text file where you will edit your console scripts to include the executable name you want and 181 00:13:26,470 --> 00:13:32,020 point it to the package name specific script file name with a particular function to run when we run 182 00:13:32,020 --> 00:13:33,610 the RAR to run command.