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#1 Introduction to Python for Data Science | Python for Data Science — Transcript

by NPTEL-NOC IITM · 2,353 words · 339 segments · language en · Watch on YouTube

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  1. 0:02[Music]
  2. 0:04you
  3. 0:06[Music]
  4. 0:14welcome to this course on Python for
  5. 0:18data science this is a four week course
  6. 0:21we are going to teach you some very
  7. 0:25basic programming aspects in Python and
  8. 0:29since this is a course that is geared
  9. 0:32towards data science towards n another
  10. 0:36course based on what has been taught in
  11. 0:39the course we will also show you two
  12. 0:42different case studies one is what we
  13. 0:45call as a function approximation case
  14. 0:47study another one a classification case
  15. 0:49study and then tell you how to solve
  16. 0:52those case studies using the programming
  17. 0:54platform that you have learned so in
  18. 0:56this first introductory lecture I am
  19. 0:58just going to talk about why are we
  20. 1:03looking at Python for data science so to
  21. 1:08look at that first we are going to look
  22. 1:10at what data science is this is
  23. 1:12something that you would have seen in
  24. 1:15other videos of courses in the NPTEL in
  25. 1:19other places data science is basically
  26. 1:22the science of analyzing raw data and
  27. 1:25deriving insights from this data and you
  28. 1:29could use multiple techniques to derive
  29. 1:31insights you could use simple
  30. 1:33statistical techniques to derive
  31. 1:35insights you could use more complicated
  32. 1:39and more sophisticated machine learning
  33. 1:41techniques to derive insights and so on
  34. 1:43nonetheless the key focus of data
  35. 1:46science is in actually deriving these
  36. 1:48insights using whatever techniques that
  37. 1:50you want to use now there's a lot of
  38. 1:52excitement about data science and this
  39. 1:54excitement comes because it's been shown
  40. 1:57that you can get very valuable insights
  41. 2:00from large data and you can get insights
  42. 2:03about how different variables change
  43. 2:07together how one variable affects
  44. 2:09another variable and so on with large
  45. 2:11data which is not very easy to simply
  46. 2:14see by very simple computation so you
  47. 2:17need to invest some time and energy into
  48. 2:19understanding how you could look at this
  49. 2:22data and derive these insights from data
  50. 2:24and from you
  51. 2:27latarian viewpoint if you look at data
  52. 2:30science in industries if you do proper
  53. 2:33data science it allows these industries
  54. 2:35to make better decisions these decisions
  55. 2:39could be in multiple fields for example
  56. 2:42companies could make better purchasing
  57. 2:45decisions better hiring decisions better
  58. 2:48decisions in terms of how to operate
  59. 2:50their processes and so on so when we
  60. 2:53talk about decisions the decisions could
  61. 2:55be across multiple verticals in an
  62. 2:58industry and data science is not only
  63. 3:02useful from an industrial perspective it
  64. 3:04is also useful in actual science as
  65. 3:07themselves so where you look at lots of
  66. 3:10data to model your system or test your
  67. 3:14hypotheses or theories about systems and
  68. 3:16so on so when we talk about data science
  69. 3:20we start by assuming that we have a
  70. 3:24large amount of data for the problem of
  71. 3:27interest and we are going to basically
  72. 3:29look at this data we're going to inspect
  73. 3:31the data we're going to clean and curate
  74. 3:34the data then we will do some
  75. 3:36transformation of the data modeling and
  76. 3:38so on before we can derive insights that
  77. 3:42are valuable to the organization are to
  78. 3:45test a theory and so on now coming to a
  79. 3:48more practical viewpoint of what we do
  80. 3:52once we have data I have these four
  81. 3:56bullet points which roughly tell you
  82. 3:59supposing you were solving a data
  83. 4:02science problem what are the steps you
  84. 4:05will do so you'll start with just having
  85. 4:08data someone gives you data and you are
  86. 4:12trying to derive insights from this data
  87. 4:14so the very first step is really to
  88. 4:16bring this data into your system so you
  89. 4:19have to read the data so that the data
  90. 4:21comes into this programming platform so
  91. 4:23that you can use this data now data
  92. 4:26could be in multiple formats so you
  93. 4:30could have data in a simple excel sheet
  94. 4:32or some other format so we will teach
  95. 4:35you how to pull data in to your
  96. 4:37programming platform from multiple data
  97. 4:40formats so
  98. 4:41that's a first step really if you think
  99. 4:42about how you're going to solve a
  100. 4:43problem these steps would be first to
  101. 4:46simply read the data and then once you
  102. 4:50read the data many times you have to do
  103. 4:53some processing with this data you could
  104. 4:55have data that that is not correct for
  105. 5:00example we all know that if you have
  106. 5:04your mobile numbers there are 10 numbers
  107. 5:06in a mobile number and if there is a
  108. 5:08column of mobile numbers and then say
  109. 5:11there is a 1 row where there are just
  110. 5:14five numbers then you know there is
  111. 5:16something wrong okay so this is a very
  112. 5:18simple check I am talking about in real
  113. 5:20data processing this gets much more
  114. 5:22complicated so once you bring the data
  115. 5:25in when you try to process this data you
  116. 5:29are going to get errors such as this so
  117. 5:32how do you remove such errors how do you
  118. 5:35clean the data is one activity that that
  119. 5:37usually precedes doing you more useful
  120. 5:42stuff with the data this is not the only
  121. 5:45issue that we look at there could be
  122. 5:49data that is missing so for example
  123. 5:51there is a variable for which you get a
  124. 5:54value in multiple situations but in some
  125. 5:56situations the value is missing so what
  126. 5:58do you do with this data do you throw
  127. 6:00the record away or you do something to
  128. 6:03fill the data and so on so these are all
  129. 6:06data processing cleaning steps so in
  130. 6:08this course we will tell you the tools
  131. 6:11that are available in Python so that you
  132. 6:12can do this data processing cleaning and
  133. 6:14so on now what you have done at this
  134. 6:18point is you have been able to get the
  135. 6:21data into the system you've been able to
  136. 6:24process and clean the data and get to a
  137. 6:26certain data file or data structure that
  138. 6:30is reasonably complete so that you think
  139. 6:32you can work with this data set at which
  140. 6:34point what you will do is you will try
  141. 6:36to summarize this data and usually
  142. 6:39summarization of this data a very simple
  143. 6:41technique would be very very simple
  144. 6:43statistical measures that you will
  145. 6:46compute you could for example computer
  146. 6:48median mode mean of a particular column
  147. 6:51okay so those are simple ideas or
  148. 6:54summarize
  149. 6:55the data you could compute variance and
  150. 6:57so on so we are going to teach you how
  151. 6:59to use this notions of statistical
  152. 7:02quantities that you can use to summarize
  153. 7:05the data once you summarize the data
  154. 7:07then another activity which is usually
  155. 7:10taken up is what is called visualization
  156. 7:13right so visualization means you look at
  157. 7:15this data and more pictorially to get
  158. 7:18insights about the data before you bring
  159. 7:20in heavy duty algorithms to bear on this
  160. 7:24data and this is a creative aspect of
  161. 7:28data science the same data could be
  162. 7:31visualized by multiple people in
  163. 7:33multiple ways and some visualizations
  164. 7:35are not only ie caching but are also
  165. 7:38much more informative than other types
  166. 7:41of visualization so this notion of
  167. 7:44plotting this data so that some of the
  168. 7:47attributes are aspects of the data are
  169. 7:51made apparent is this notion of
  170. 7:53visualization and there are tools in
  171. 7:56Python that will teach you in terms of
  172. 7:59how you visualize this data so at this
  173. 8:01point you have taken the data you've
  174. 8:03cleaned the data got a set of data
  175. 8:05points or data structure that you can
  176. 8:07work with you have done some basic
  177. 8:10summary of this data that gives you some
  178. 8:12insights you also looked at it more
  179. 8:15visually and you've got some more
  180. 8:17insights but when you have large amount
  181. 8:19of data big data the last step is really
  182. 8:21deriving those insights which are not
  183. 8:23readily apparent either through
  184. 8:25visualization or through simple summary
  185. 8:28of data so how do we then go and look at
  186. 8:30more sophisticated analytics or analysis
  187. 8:34of data so that these insights come out
  188. 8:38and that's where machine learning comes
  189. 8:40and as a part of this course when you
  190. 8:43see the progress of this course you will
  191. 8:45notice that you will go through all of
  192. 8:47this so that you are ready to look at
  193. 8:49data science problems in a structured
  194. 8:51format and then use Python as a tool to
  195. 8:54solve some of these problems
  196. 8:56now why Python for doing all of this the
  197. 9:01number one reason is that there are
  198. 9:04these Python libraries which already are
  199. 9:07geared towards
  200. 9:08doing many of the things that we talked
  201. 9:10about so that it becomes easy for one to
  202. 9:14program and very quickly you can get
  203. 9:17some interesting outcomes out of what we
  204. 9:20are trying to do so there are as we
  205. 9:23talked about in the previous slide you
  206. 9:25need to do data manipulation and
  207. 9:27pre-processing there are lots of
  208. 9:30functions libraries in Python where you
  209. 9:33can do data wrangling manipulation and
  210. 9:36so on from a data summary viewpoint
  211. 9:39there are many of these statistical
  212. 9:42calculations that you want to do are
  213. 9:45already pre-programmed and you have to
  214. 9:47simply invoke them with your data to be
  215. 9:49able to show data summary the next step
  216. 9:52we talked about visualization there are
  217. 9:54libraries in Python which can be used to
  218. 9:58do the visualization and finally for the
  219. 10:01more sophisticated analysis that we
  220. 10:03talked about all kinds of machine
  221. 10:07learning algorithms are already pre
  222. 10:09coded available as libraries in Python
  223. 10:12so again once you understand some some
  224. 10:15bit about these functions and once you
  225. 10:18get comfortable working in Python then
  226. 10:20applying certain machine learning
  227. 10:22algorithms for these problems become
  228. 10:23trivial so you simply call these
  229. 10:25libraries and then run these algorithms
  230. 10:28at a higher level so in the previous
  231. 10:31slide we we talked about a flow process
  232. 10:35for how I get the data in clean it and
  233. 10:38all the way up to insights and then
  234. 10:40parallely we said why Python makes it
  235. 10:43easy for us to do all of this if you if
  236. 10:46you go back if you go forward a little
  237. 10:49more and then ask in terms of the other
  238. 10:53advantages of Python which are little
  239. 10:56more than just very simple data science
  240. 10:59activities Python provides you several
  241. 11:04libraries and it's being continuously
  242. 11:07improved so anytime there is a new
  243. 11:09algorithm those are coming into the set
  244. 11:14of libraries so in that sense it's very
  245. 11:16varied and there is also a good user
  246. 11:20community so if there are some issues
  247. 11:22with new libraries and so on and those
  248. 11:24are fixed so that you get robust library
  249. 11:27to work with and we talk about data and
  250. 11:31data can be of different scale so the
  251. 11:35examples that you will see in this
  252. 11:36course are data of reasonably small size
  253. 11:40but in real life problems you're going
  254. 11:42to look at data which is much larger
  255. 11:44which we call as big data so python has
  256. 11:48an ability to integrate with big data
  257. 11:51frameworks like Hadoop SPARC and so on
  258. 11:53and Python also allows you to do more
  259. 11:57sophisticated programming
  260. 11:58object-oriented programming and
  261. 12:01functional programming Python with all
  262. 12:05of this sophisticated tools and
  263. 12:08abilities is still reasonably a simple
  264. 12:12language to learn it's reasonably fast
  265. 12:13to prototype and it also gives you the
  266. 12:16ability to work with data which is in
  267. 12:18your local machine or in a cloud and so
  268. 12:21on so these are all things that one
  269. 12:24looks for when one looks at a
  270. 12:27programming platform which is capable of
  271. 12:31solving problems in in in real life
  272. 12:35right so these are real problems that
  273. 12:37you can solve these are not only toy
  274. 12:39examples but real applications that you
  275. 12:43can build data science applications that
  276. 12:45you can build with Python and just as
  277. 12:50another pointer in terms of ye I we
  278. 12:54believe that Python is something that a
  279. 12:57lot of our students and professionals in
  280. 12:59India should learn as you know there are
  281. 13:03tools which are paid tools for machine
  282. 13:06learning with all of these libraries and
  283. 13:08so on and there are also open source
  284. 13:10tools and in India based on a survey
  285. 13:14most people of course
  286. 13:18prefer open-source tools for a variety
  287. 13:21of reasons cause being one because it's
  288. 13:23free to use but also if it's just free
  289. 13:27to use but it doesn't have a robust user
  290. 13:29community then it's not really very
  291. 13:31useful that's where Python really scores
  292. 13:33in terms of a robust user community
  293. 13:35which can help with people working in
  294. 13:39Python so it's both open-source and
  295. 13:41there is a robust user community both of
  296. 13:44which are advantageous for Python and if
  297. 13:48you think of other competing languages
  298. 13:52for machine learning if you look at this
  299. 13:54chart in India about 44% of the people
  300. 13:58who were surveyed said they use Python
  301. 14:02or they prefer Python and of course a
  302. 14:04close second is art in fact our was much
  303. 14:07more preferred a few years back but over
  304. 14:10the last few years in India a python is
  305. 14:13starting to become the programming
  306. 14:15platform of choice so in that sense it's
  307. 14:18a good language to learn because the
  308. 14:20opportunities for jobs and so on lot
  309. 14:25more when when you're comfortable with
  310. 14:27Python as a language so with this I will
  311. 14:31stop this brief introduction on why
  312. 14:33Python for data science I hope I've
  313. 14:36given you an idea of the fact that while
  314. 14:40we are going to teach you
  315. 14:41Python as a programming language please
  316. 14:44keep in mind that each module that we
  317. 14:46teach in this is actually geared towards
  318. 14:50data science so as we teach Python we
  319. 14:53will make the connections to how you
  320. 14:55will use some of the things that you're
  321. 14:57seeing in data science and all of this
  322. 14:59will culminate with these two case
  323. 15:02studies that will bring all of these
  324. 15:04ideas together in terms of both giving
  325. 15:08you an idea and an understanding of how
  326. 15:10the data science problem will be solved
  327. 15:12and also how it will be solved in Python
  328. 15:15which is a program of choice currently
  329. 15:17in India so I hope this short four-week
  330. 15:21course helps you quickly get on to this
  331. 15:25programming platform and then learn data
  332. 15:29science and then you can enhance you
  333. 15:31skills with much more detailed
  334. 15:35understanding of both the programming
  335. 15:36language and data science techniques
  336. 15:38thank you
  337. 15:40[Music]
  338. 15:56you
  339. 15:57[Music]

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