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5_Control_Flow.ipynb 12 kB

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  1. {
  2. "cells": [
  3. {
  4. "cell_type": "markdown",
  5. "metadata": {},
  6. "source": [
  7. "# 控制流语句"
  8. ]
  9. },
  10. {
  11. "cell_type": "markdown",
  12. "metadata": {},
  13. "source": [
  14. "## 1. If"
  15. ]
  16. },
  17. {
  18. "cell_type": "markdown",
  19. "metadata": {},
  20. "source": [
  21. "if some_condition:\n",
  22. " \n",
  23. " algorithm"
  24. ]
  25. },
  26. {
  27. "cell_type": "code",
  28. "execution_count": 1,
  29. "metadata": {
  30. "scrolled": true
  31. },
  32. "outputs": [
  33. {
  34. "name": "stdout",
  35. "output_type": "stream",
  36. "text": [
  37. "Welcome!\n"
  38. ]
  39. }
  40. ],
  41. "source": [
  42. "x = 4\n",
  43. "if x >10: \n",
  44. " print(\"Hello\")\n",
  45. "else: \n",
  46. " print(\"Welcome!\")"
  47. ]
  48. },
  49. {
  50. "cell_type": "code",
  51. "execution_count": 2,
  52. "metadata": {},
  53. "outputs": [],
  54. "source": [
  55. "x = 4\n",
  56. "if x > 10: print(\"Hello\")"
  57. ]
  58. },
  59. {
  60. "cell_type": "markdown",
  61. "metadata": {},
  62. "source": [
  63. "## 2. If-else"
  64. ]
  65. },
  66. {
  67. "cell_type": "markdown",
  68. "metadata": {},
  69. "source": [
  70. "if some_condition:\n",
  71. " \n",
  72. " algorithm\n",
  73. " \n",
  74. "else:\n",
  75. " \n",
  76. " algorithm"
  77. ]
  78. },
  79. {
  80. "cell_type": "code",
  81. "execution_count": 3,
  82. "metadata": {},
  83. "outputs": [
  84. {
  85. "name": "stdout",
  86. "output_type": "stream",
  87. "text": [
  88. "hello\n"
  89. ]
  90. }
  91. ],
  92. "source": [
  93. "x = 12\n",
  94. "if x > 10:\n",
  95. " print(\"hello\")\n",
  96. "else:\n",
  97. " print(\"world\")"
  98. ]
  99. },
  100. {
  101. "cell_type": "markdown",
  102. "metadata": {},
  103. "source": [
  104. "## 3. if-elif"
  105. ]
  106. },
  107. {
  108. "cell_type": "markdown",
  109. "metadata": {},
  110. "source": [
  111. "if some_condition:\n",
  112. " \n",
  113. " algorithm\n",
  114. "\n",
  115. "elif some_condition:\n",
  116. " \n",
  117. " algorithm\n",
  118. "\n",
  119. "else:\n",
  120. " \n",
  121. " algorithm"
  122. ]
  123. },
  124. {
  125. "cell_type": "code",
  126. "execution_count": 3,
  127. "metadata": {},
  128. "outputs": [
  129. {
  130. "name": "stdout",
  131. "output_type": "stream",
  132. "text": [
  133. "x<y\n"
  134. ]
  135. }
  136. ],
  137. "source": [
  138. "x = 10\n",
  139. "y = 12\n",
  140. "if x > y:\n",
  141. " print(\"x>y\")\n",
  142. "elif x < y:\n",
  143. " print(\"x<y\")\n",
  144. "else:\n",
  145. " print(\"x=y\")"
  146. ]
  147. },
  148. {
  149. "cell_type": "markdown",
  150. "metadata": {},
  151. "source": [
  152. "在if语句里的if语句,if-elif或if-else都被称为嵌套if语句。"
  153. ]
  154. },
  155. {
  156. "cell_type": "code",
  157. "execution_count": 4,
  158. "metadata": {},
  159. "outputs": [
  160. {
  161. "name": "stdout",
  162. "output_type": "stream",
  163. "text": [
  164. "x<y\n",
  165. "x=10\n"
  166. ]
  167. }
  168. ],
  169. "source": [
  170. "x = 10\n",
  171. "y = 12\n",
  172. "if x > y:\n",
  173. " print(\"x>y\")\n",
  174. "elif x < y:\n",
  175. " print(\"x<y\")\n",
  176. " if x==10:\n",
  177. " print(\"x=10\")\n",
  178. " else:\n",
  179. " print(\"invalid\")\n",
  180. "else:\n",
  181. " print(\"x=y\")"
  182. ]
  183. },
  184. {
  185. "cell_type": "markdown",
  186. "metadata": {},
  187. "source": [
  188. "## 4. 循环"
  189. ]
  190. },
  191. {
  192. "cell_type": "markdown",
  193. "metadata": {},
  194. "source": [
  195. "### 4.1 for"
  196. ]
  197. },
  198. {
  199. "cell_type": "markdown",
  200. "metadata": {},
  201. "source": [
  202. "for variable in something:\n",
  203. " \n",
  204. " algorithm"
  205. ]
  206. },
  207. {
  208. "cell_type": "code",
  209. "execution_count": 4,
  210. "metadata": {},
  211. "outputs": [
  212. {
  213. "name": "stdout",
  214. "output_type": "stream",
  215. "text": [
  216. "0\n",
  217. "1\n",
  218. "2\n",
  219. "3\n",
  220. "4\n"
  221. ]
  222. }
  223. ],
  224. "source": [
  225. "for i in range(5):\n",
  226. " print(i)"
  227. ]
  228. },
  229. {
  230. "cell_type": "code",
  231. "execution_count": 5,
  232. "metadata": {},
  233. "outputs": [
  234. {
  235. "name": "stdout",
  236. "output_type": "stream",
  237. "text": [
  238. "1\n",
  239. "2\n",
  240. "5\n",
  241. "6\n"
  242. ]
  243. }
  244. ],
  245. "source": [
  246. "a = [1, 2, 5, 6]\n",
  247. "for i in a:\n",
  248. " print(i)"
  249. ]
  250. },
  251. {
  252. "cell_type": "markdown",
  253. "metadata": {},
  254. "source": [
  255. "在上面的例子中,我遍历了0,1,2,3,4。每次它取每个值并在循环内执行算法。还可以遍历如下所示的嵌套列表。"
  256. ]
  257. },
  258. {
  259. "cell_type": "code",
  260. "execution_count": 6,
  261. "metadata": {},
  262. "outputs": [
  263. {
  264. "name": "stdout",
  265. "output_type": "stream",
  266. "text": [
  267. "[1, 2, 3]\n",
  268. "[4, 5, 6]\n",
  269. "[7, 8, 9]\n"
  270. ]
  271. }
  272. ],
  273. "source": [
  274. "list_of_lists = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]\n",
  275. "for list1 in list_of_lists:\n",
  276. " print(list1)"
  277. ]
  278. },
  279. {
  280. "cell_type": "markdown",
  281. "metadata": {},
  282. "source": [
  283. "嵌套的for循环的一个用例是,"
  284. ]
  285. },
  286. {
  287. "cell_type": "code",
  288. "execution_count": 7,
  289. "metadata": {},
  290. "outputs": [
  291. {
  292. "name": "stdout",
  293. "output_type": "stream",
  294. "text": [
  295. "1\n",
  296. "2\n",
  297. "3\n",
  298. "\n",
  299. "4\n",
  300. "5\n",
  301. "6\n",
  302. "\n",
  303. "7\n",
  304. "8\n",
  305. "9\n",
  306. "\n"
  307. ]
  308. }
  309. ],
  310. "source": [
  311. "list_of_lists = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]\n",
  312. "for list1 in list_of_lists:\n",
  313. " for x in list1:\n",
  314. " print(x)\n",
  315. " print()"
  316. ]
  317. },
  318. {
  319. "cell_type": "markdown",
  320. "metadata": {},
  321. "source": [
  322. "### 4.2 while"
  323. ]
  324. },
  325. {
  326. "cell_type": "markdown",
  327. "metadata": {},
  328. "source": [
  329. "while some_condition:\n",
  330. " \n",
  331. " algorithm"
  332. ]
  333. },
  334. {
  335. "cell_type": "code",
  336. "execution_count": 8,
  337. "metadata": {},
  338. "outputs": [
  339. {
  340. "name": "stdout",
  341. "output_type": "stream",
  342. "text": [
  343. "1\n",
  344. "4\n",
  345. "Bye\n",
  346. "looping 4\n",
  347. "looping 5\n",
  348. "looping 6\n",
  349. "looping 7\n",
  350. "looping 8\n",
  351. "looping 9\n",
  352. "looping 10\n",
  353. "looping 11\n"
  354. ]
  355. }
  356. ],
  357. "source": [
  358. "i = 1\n",
  359. "while i < 3:\n",
  360. " print(i ** 2)\n",
  361. " i = i+1\n",
  362. "print('Bye')\n",
  363. "\n",
  364. "# do-untile\n",
  365. "while True:\n",
  366. " #do something\n",
  367. " i = i+1\n",
  368. " print('looping %3d' % i)\n",
  369. " \n",
  370. " # check \n",
  371. " if i>10: break"
  372. ]
  373. },
  374. {
  375. "cell_type": "markdown",
  376. "metadata": {},
  377. "source": [
  378. "## 5. break"
  379. ]
  380. },
  381. {
  382. "cell_type": "markdown",
  383. "metadata": {},
  384. "source": [
  385. "顾名思义。它用于在执行循环时,当条件为真时中断循环。"
  386. ]
  387. },
  388. {
  389. "cell_type": "code",
  390. "execution_count": 9,
  391. "metadata": {},
  392. "outputs": [
  393. {
  394. "name": "stdout",
  395. "output_type": "stream",
  396. "text": [
  397. "0\n",
  398. "1\n",
  399. "2\n",
  400. "3\n",
  401. "4\n",
  402. "5\n",
  403. "6\n",
  404. "7\n"
  405. ]
  406. }
  407. ],
  408. "source": [
  409. "for i in range(100):\n",
  410. " print(i)\n",
  411. " if i>=7:\n",
  412. " break"
  413. ]
  414. },
  415. {
  416. "cell_type": "markdown",
  417. "metadata": {},
  418. "source": [
  419. "## 6. continue"
  420. ]
  421. },
  422. {
  423. "cell_type": "markdown",
  424. "metadata": {},
  425. "source": [
  426. "这将继续循环的其余部分。有时,当满足条件时,循环有可能终止。这可以使用continue语句避免。"
  427. ]
  428. },
  429. {
  430. "cell_type": "code",
  431. "execution_count": 10,
  432. "metadata": {},
  433. "outputs": [
  434. {
  435. "name": "stdout",
  436. "output_type": "stream",
  437. "text": [
  438. "0\n",
  439. "1\n",
  440. "2\n",
  441. "3\n",
  442. "4\n",
  443. "The end.\n",
  444. "The end.\n",
  445. "The end.\n",
  446. "The end.\n",
  447. "The end.\n"
  448. ]
  449. }
  450. ],
  451. "source": [
  452. "for i in range(10):\n",
  453. " if i>4:\n",
  454. " print(\"The end.\")\n",
  455. " continue\n",
  456. " if i<7:\n",
  457. " print(i)"
  458. ]
  459. },
  460. {
  461. "cell_type": "markdown",
  462. "metadata": {},
  463. "source": [
  464. "## 7. 列表推导(List Comprehensions)"
  465. ]
  466. },
  467. {
  468. "cell_type": "markdown",
  469. "metadata": {},
  470. "source": [
  471. "Python可以使用列表推导模式,用一行代码就可以很容易地生成所需的列表。例如,如果我需要生成27的倍数,用`for`循环缩写的代码如下:"
  472. ]
  473. },
  474. {
  475. "cell_type": "code",
  476. "execution_count": 12,
  477. "metadata": {},
  478. "outputs": [
  479. {
  480. "name": "stdout",
  481. "output_type": "stream",
  482. "text": [
  483. "[27, 54, 81, 108, 135, 162, 189, 216, 243, 270]\n"
  484. ]
  485. }
  486. ],
  487. "source": [
  488. "res = []\n",
  489. "for i in range(1,11):\n",
  490. " x = 27*i\n",
  491. " res.append(x)\n",
  492. "print(res)"
  493. ]
  494. },
  495. {
  496. "cell_type": "markdown",
  497. "metadata": {},
  498. "source": [
  499. "由于你需要生成另一个列表,所以列表推导是解决这个问题的更有效的方法(建议大家使用这样的方式)"
  500. ]
  501. },
  502. {
  503. "cell_type": "code",
  504. "execution_count": 11,
  505. "metadata": {},
  506. "outputs": [
  507. {
  508. "data": {
  509. "text/plain": [
  510. "[27, 54, 81, 108, 135, 162, 189, 216, 243, 270]"
  511. ]
  512. },
  513. "execution_count": 11,
  514. "metadata": {},
  515. "output_type": "execute_result"
  516. }
  517. ],
  518. "source": [
  519. "[27*x for x in range(1,11)]"
  520. ]
  521. },
  522. {
  523. "cell_type": "markdown",
  524. "metadata": {},
  525. "source": [
  526. "将表达方式用方括号括起来。"
  527. ]
  528. },
  529. {
  530. "cell_type": "markdown",
  531. "metadata": {},
  532. "source": [
  533. "理解代码,代码的第一个位总是算法,然后留下一个空格,然后写必要的循环。但是你可能想知道嵌套循环可以扩展到列表理解吗?是的,你可以。"
  534. ]
  535. },
  536. {
  537. "cell_type": "code",
  538. "execution_count": 12,
  539. "metadata": {},
  540. "outputs": [
  541. {
  542. "data": {
  543. "text/plain": [
  544. "[27, 54, 81, 108, 135, 162, 189, 216, 243, 270]"
  545. ]
  546. },
  547. "execution_count": 12,
  548. "metadata": {},
  549. "output_type": "execute_result"
  550. }
  551. ],
  552. "source": [
  553. "[27*x for x in range(1,20) if x<=10]"
  554. ]
  555. },
  556. {
  557. "cell_type": "code",
  558. "execution_count": 13,
  559. "metadata": {
  560. "scrolled": true
  561. },
  562. "outputs": [
  563. {
  564. "data": {
  565. "text/plain": [
  566. "{'27': 27,\n",
  567. " '54': 54,\n",
  568. " '81': 81,\n",
  569. " '108': 108,\n",
  570. " '135': 135,\n",
  571. " '162': 162,\n",
  572. " '189': 189,\n",
  573. " '216': 216,\n",
  574. " '243': 243,\n",
  575. " '270': 270}"
  576. ]
  577. },
  578. "execution_count": 13,
  579. "metadata": {},
  580. "output_type": "execute_result"
  581. }
  582. ],
  583. "source": [
  584. "{str(27*x):27*x for x in range(1,20) if x<=10}"
  585. ]
  586. },
  587. {
  588. "cell_type": "code",
  589. "execution_count": 14,
  590. "metadata": {},
  591. "outputs": [
  592. {
  593. "data": {
  594. "text/plain": [
  595. "(27, 54, 81, 108, 135, 162, 189, 216, 243, 270)"
  596. ]
  597. },
  598. "execution_count": 14,
  599. "metadata": {},
  600. "output_type": "execute_result"
  601. }
  602. ],
  603. "source": [
  604. "tuple((27*x for x in range(1,20) if x<=10))"
  605. ]
  606. },
  607. {
  608. "cell_type": "markdown",
  609. "metadata": {},
  610. "source": [
  611. "让我再加一个循环,让你更好地理解,"
  612. ]
  613. },
  614. {
  615. "cell_type": "code",
  616. "execution_count": 15,
  617. "metadata": {},
  618. "outputs": [
  619. {
  620. "data": {
  621. "text/plain": [
  622. "[1, 2, 3, 4, 28, 29, 30, 31, 55, 56, 57, 58]"
  623. ]
  624. },
  625. "execution_count": 15,
  626. "metadata": {},
  627. "output_type": "execute_result"
  628. }
  629. ],
  630. "source": [
  631. "[27*i+z for i in range(5) if i<3 for z in range(1,5)]"
  632. ]
  633. }
  634. ],
  635. "metadata": {
  636. "kernelspec": {
  637. "display_name": "Python 3",
  638. "language": "python",
  639. "name": "python3"
  640. },
  641. "language_info": {
  642. "codemirror_mode": {
  643. "name": "ipython",
  644. "version": 3
  645. },
  646. "file_extension": ".py",
  647. "mimetype": "text/x-python",
  648. "name": "python",
  649. "nbconvert_exporter": "python",
  650. "pygments_lexer": "ipython3",
  651. "version": "3.7.9"
  652. }
  653. },
  654. "nbformat": 4,
  655. "nbformat_minor": 1
  656. }

机器学习越来越多应用到飞行器、机器人等领域,其目的是利用计算机实现类似人类的智能,从而实现装备的智能化与无人化。本课程旨在引导学生掌握机器学习的基本知识、典型方法与技术,通过具体的应用案例激发学生对该学科的兴趣,鼓励学生能够从人工智能的角度来分析、解决飞行器、机器人所面临的问题和挑战。本课程主要内容包括Python编程基础,机器学习模型,无监督学习、监督学习、深度学习基础知识与实现,并学习如何利用机器学习解决实际问题,从而全面提升自我的《综合能力》。