In [1]:

    

import numpy as np


    

In [3]:

    

list = np.array([1,2,3])


    

In [4]:

    

list


    

    
Out[4]:





array([1, 2, 3])

In [5]:

    

a = np.arange(1000)
%time a2 = a**2


    

    




Wall time: 999 µs

In [7]:

    

a*2 # array의 경우 각각의 a 원소에 값을 계산함


    

    
Out[7]:





array([   0,    2,    4,    6,    8,   10,   12,   14,   16,   18,   20,
         22,   24,   26,   28,   30,   32,   34,   36,   38,   40,   42,
         44,   46,   48,   50,   52,   54,   56,   58,   60,   62,   64,
         66,   68,   70,   72,   74,   76,   78,   80,   82,   84,   86,
         88,   90,   92,   94,   96,   98,  100,  102,  104,  106,  108,
        110,  112,  114,  116,  118,  120,  122,  124,  126,  128,  130,
        132,  134,  136,  138,  140,  142,  144,  146,  148,  150,  152,
        154,  156,  158,  160,  162,  164,  166,  168,  170,  172,  174,
        176,  178,  180,  182,  184,  186,  188,  190,  192,  194,  196,
        198,  200,  202,  204,  206,  208,  210,  212,  214,  216,  218,
        220,  222,  224,  226,  228,  230,  232,  234,  236,  238,  240,
        242,  244,  246,  248,  250,  252,  254,  256,  258,  260,  262,
        264,  266,  268,  270,  272,  274,  276,  278,  280,  282,  284,
        286,  288,  290,  292,  294,  296,  298,  300,  302,  304,  306,
        308,  310,  312,  314,  316,  318,  320,  322,  324,  326,  328,
        330,  332,  334,  336,  338,  340,  342,  344,  346,  348,  350,
        352,  354,  356,  358,  360,  362,  364,  366,  368,  370,  372,
        374,  376,  378,  380,  382,  384,  386,  388,  390,  392,  394,
        396,  398,  400,  402,  404,  406,  408,  410,  412,  414,  416,
        418,  420,  422,  424,  426,  428,  430,  432,  434,  436,  438,
        440,  442,  444,  446,  448,  450,  452,  454,  456,  458,  460,
        462,  464,  466,  468,  470,  472,  474,  476,  478,  480,  482,
        484,  486,  488,  490,  492,  494,  496,  498,  500,  502,  504,
        506,  508,  510,  512,  514,  516,  518,  520,  522,  524,  526,
        528,  530,  532,  534,  536,  538,  540,  542,  544,  546,  548,
        550,  552,  554,  556,  558,  560,  562,  564,  566,  568,  570,
        572,  574,  576,  578,  580,  582,  584,  586,  588,  590,  592,
        594,  596,  598,  600,  602,  604,  606,  608,  610,  612,  614,
        616,  618,  620,  622,  624,  626,  628,  630,  632,  634,  636,
        638,  640,  642,  644,  646,  648,  650,  652,  654,  656,  658,
        660,  662,  664,  666,  668,  670,  672,  674,  676,  678,  680,
        682,  684,  686,  688,  690,  692,  694,  696,  698,  700,  702,
        704,  706,  708,  710,  712,  714,  716,  718,  720,  722,  724,
        726,  728,  730,  732,  734,  736,  738,  740,  742,  744,  746,
        748,  750,  752,  754,  756,  758,  760,  762,  764,  766,  768,
        770,  772,  774,  776,  778,  780,  782,  784,  786,  788,  790,
        792,  794,  796,  798,  800,  802,  804,  806,  808,  810,  812,
        814,  816,  818,  820,  822,  824,  826,  828,  830,  832,  834,
        836,  838,  840,  842,  844,  846,  848,  850,  852,  854,  856,
        858,  860,  862,  864,  866,  868,  870,  872,  874,  876,  878,
        880,  882,  884,  886,  888,  890,  892,  894,  896,  898,  900,
        902,  904,  906,  908,  910,  912,  914,  916,  918,  920,  922,
        924,  926,  928,  930,  932,  934,  936,  938,  940,  942,  944,
        946,  948,  950,  952,  954,  956,  958,  960,  962,  964,  966,
        968,  970,  972,  974,  976,  978,  980,  982,  984,  986,  988,
        990,  992,  994,  996,  998, 1000, 1002, 1004, 1006, 1008, 1010,
       1012, 1014, 1016, 1018, 1020, 1022, 1024, 1026, 1028, 1030, 1032,
       1034, 1036, 1038, 1040, 1042, 1044, 1046, 1048, 1050, 1052, 1054,
       1056, 1058, 1060, 1062, 1064, 1066, 1068, 1070, 1072, 1074, 1076,
       1078, 1080, 1082, 1084, 1086, 1088, 1090, 1092, 1094, 1096, 1098,
       1100, 1102, 1104, 1106, 1108, 1110, 1112, 1114, 1116, 1118, 1120,
       1122, 1124, 1126, 1128, 1130, 1132, 1134, 1136, 1138, 1140, 1142,
       1144, 1146, 1148, 1150, 1152, 1154, 1156, 1158, 1160, 1162, 1164,
       1166, 1168, 1170, 1172, 1174, 1176, 1178, 1180, 1182, 1184, 1186,
       1188, 1190, 1192, 1194, 1196, 1198, 1200, 1202, 1204, 1206, 1208,
       1210, 1212, 1214, 1216, 1218, 1220, 1222, 1224, 1226, 1228, 1230,
       1232, 1234, 1236, 1238, 1240, 1242, 1244, 1246, 1248, 1250, 1252,
       1254, 1256, 1258, 1260, 1262, 1264, 1266, 1268, 1270, 1272, 1274,
       1276, 1278, 1280, 1282, 1284, 1286, 1288, 1290, 1292, 1294, 1296,
       1298, 1300, 1302, 1304, 1306, 1308, 1310, 1312, 1314, 1316, 1318,
       1320, 1322, 1324, 1326, 1328, 1330, 1332, 1334, 1336, 1338, 1340,
       1342, 1344, 1346, 1348, 1350, 1352, 1354, 1356, 1358, 1360, 1362,
       1364, 1366, 1368, 1370, 1372, 1374, 1376, 1378, 1380, 1382, 1384,
       1386, 1388, 1390, 1392, 1394, 1396, 1398, 1400, 1402, 1404, 1406,
       1408, 1410, 1412, 1414, 1416, 1418, 1420, 1422, 1424, 1426, 1428,
       1430, 1432, 1434, 1436, 1438, 1440, 1442, 1444, 1446, 1448, 1450,
       1452, 1454, 1456, 1458, 1460, 1462, 1464, 1466, 1468, 1470, 1472,
       1474, 1476, 1478, 1480, 1482, 1484, 1486, 1488, 1490, 1492, 1494,
       1496, 1498, 1500, 1502, 1504, 1506, 1508, 1510, 1512, 1514, 1516,
       1518, 1520, 1522, 1524, 1526, 1528, 1530, 1532, 1534, 1536, 1538,
       1540, 1542, 1544, 1546, 1548, 1550, 1552, 1554, 1556, 1558, 1560,
       1562, 1564, 1566, 1568, 1570, 1572, 1574, 1576, 1578, 1580, 1582,
       1584, 1586, 1588, 1590, 1592, 1594, 1596, 1598, 1600, 1602, 1604,
       1606, 1608, 1610, 1612, 1614, 1616, 1618, 1620, 1622, 1624, 1626,
       1628, 1630, 1632, 1634, 1636, 1638, 1640, 1642, 1644, 1646, 1648,
       1650, 1652, 1654, 1656, 1658, 1660, 1662, 1664, 1666, 1668, 1670,
       1672, 1674, 1676, 1678, 1680, 1682, 1684, 1686, 1688, 1690, 1692,
       1694, 1696, 1698, 1700, 1702, 1704, 1706, 1708, 1710, 1712, 1714,
       1716, 1718, 1720, 1722, 1724, 1726, 1728, 1730, 1732, 1734, 1736,
       1738, 1740, 1742, 1744, 1746, 1748, 1750, 1752, 1754, 1756, 1758,
       1760, 1762, 1764, 1766, 1768, 1770, 1772, 1774, 1776, 1778, 1780,
       1782, 1784, 1786, 1788, 1790, 1792, 1794, 1796, 1798, 1800, 1802,
       1804, 1806, 1808, 1810, 1812, 1814, 1816, 1818, 1820, 1822, 1824,
       1826, 1828, 1830, 1832, 1834, 1836, 1838, 1840, 1842, 1844, 1846,
       1848, 1850, 1852, 1854, 1856, 1858, 1860, 1862, 1864, 1866, 1868,
       1870, 1872, 1874, 1876, 1878, 1880, 1882, 1884, 1886, 1888, 1890,
       1892, 1894, 1896, 1898, 1900, 1902, 1904, 1906, 1908, 1910, 1912,
       1914, 1916, 1918, 1920, 1922, 1924, 1926, 1928, 1930, 1932, 1934,
       1936, 1938, 1940, 1942, 1944, 1946, 1948, 1950, 1952, 1954, 1956,
       1958, 1960, 1962, 1964, 1966, 1968, 1970, 1972, 1974, 1976, 1978,
       1980, 1982, 1984, 1986, 1988, 1990, 1992, 1994, 1996, 1998])

In [12]:

    

a1 = [i for i in range(1, 1000)]


    

In [16]:

    

print(a1*2) # list의 경우 a1을 그냥 2번 나열함


    

    




[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330, 331, 332, 333, 334, 335, 336, 337, 338, 339, 340, 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, 351, 352, 353, 354, 355, 356, 357, 358, 359, 360, 361, 362, 363, 364, 365, 366, 367, 368, 369, 370, 371, 372, 373, 374, 375, 376, 377, 378, 379, 380, 381, 382, 383, 384, 385, 386, 387, 388, 389, 390, 391, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404, 405, 406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 432, 433, 434, 435, 436, 437, 438, 439, 440, 441, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 452, 453, 454, 455, 456, 457, 458, 459, 460, 461, 462, 463, 464, 465, 466, 467, 468, 469, 470, 471, 472, 473, 474, 475, 476, 477, 478, 479, 480, 481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 495, 496, 497, 498, 499, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511, 512, 513, 514, 515, 516, 517, 518, 519, 520, 521, 522, 523, 524, 525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 537, 538, 539, 540, 541, 542, 543, 544, 545, 546, 547, 548, 549, 550, 551, 552, 553, 554, 555, 556, 557, 558, 559, 560, 561, 562, 563, 564, 565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580, 581, 582, 583, 584, 585, 586, 587, 588, 589, 590, 591, 592, 593, 594, 595, 596, 597, 598, 599, 600, 601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620, 621, 622, 623, 624, 625, 626, 627, 628, 629, 630, 631, 632, 633, 634, 635, 636, 637, 638, 639, 640, 641, 642, 643, 644, 645, 646, 647, 648, 649, 650, 651, 652, 653, 654, 655, 656, 657, 658, 659, 660, 661, 662, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689, 690, 691, 692, 693, 694, 695, 696, 697, 698, 699, 700, 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, 720, 721, 722, 723, 724, 725, 726, 727, 728, 729, 730, 731, 732, 733, 734, 735, 736, 737, 738, 739, 740, 741, 742, 743, 744, 745, 746, 747, 748, 749, 750, 751, 752, 753, 754, 755, 756, 757, 758, 759, 760, 761, 762, 763, 764, 765, 766, 767, 768, 769, 770, 771, 772, 773, 774, 775, 776, 777, 778, 779, 780, 781, 782, 783, 784, 785, 786, 787, 788, 789, 790, 791, 792, 793, 794, 795, 796, 797, 798, 799, 800, 801, 802, 803, 804, 805, 806, 807, 808, 809, 810, 811, 812, 813, 814, 815, 816, 817, 818, 819, 820, 821, 822, 823, 824, 825, 826, 827, 828, 829, 830, 831, 832, 833, 834, 835, 836, 837, 838, 839, 840, 841, 842, 843, 844, 845, 846, 847, 848, 849, 850, 851, 852, 853, 854, 855, 856, 857, 858, 859, 860, 861, 862, 863, 864, 865, 866, 867, 868, 869, 870, 871, 872, 873, 874, 875, 876, 877, 878, 879, 880, 881, 882, 883, 884, 885, 886, 887, 888, 889, 890, 891, 892, 893, 894, 895, 896, 897, 898, 899, 900, 901, 902, 903, 904, 905, 906, 907, 908, 909, 910, 911, 912, 913, 914, 915, 916, 917, 918, 919, 920, 921, 922, 923, 924, 925, 926, 927, 928, 929, 930, 931, 932, 933, 934, 935, 936, 937, 938, 939, 940, 941, 942, 943, 944, 945, 946, 947, 948, 949, 950, 951, 952, 953, 954, 955, 956, 957, 958, 959, 960, 961, 962, 963, 964, 965, 966, 967, 968, 969, 970, 971, 972, 973, 974, 975, 976, 977, 978, 979, 980, 981, 982, 983, 984, 985, 986, 987, 988, 989, 990, 991, 992, 993, 994, 995, 996, 997, 998, 999, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330, 331, 332, 333, 334, 335, 336, 337, 338, 339, 340, 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, 351, 352, 353, 354, 355, 356, 357, 358, 359, 360, 361, 362, 363, 364, 365, 366, 367, 368, 369, 370, 371, 372, 373, 374, 375, 376, 377, 378, 379, 380, 381, 382, 383, 384, 385, 386, 387, 388, 389, 390, 391, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404, 405, 406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 432, 433, 434, 435, 436, 437, 438, 439, 440, 441, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 452, 453, 454, 455, 456, 457, 458, 459, 460, 461, 462, 463, 464, 465, 466, 467, 468, 469, 470, 471, 472, 473, 474, 475, 476, 477, 478, 479, 480, 481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 495, 496, 497, 498, 499, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511, 512, 513, 514, 515, 516, 517, 518, 519, 520, 521, 522, 523, 524, 525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 537, 538, 539, 540, 541, 542, 543, 544, 545, 546, 547, 548, 549, 550, 551, 552, 553, 554, 555, 556, 557, 558, 559, 560, 561, 562, 563, 564, 565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580, 581, 582, 583, 584, 585, 586, 587, 588, 589, 590, 591, 592, 593, 594, 595, 596, 597, 598, 599, 600, 601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620, 621, 622, 623, 624, 625, 626, 627, 628, 629, 630, 631, 632, 633, 634, 635, 636, 637, 638, 639, 640, 641, 642, 643, 644, 645, 646, 647, 648, 649, 650, 651, 652, 653, 654, 655, 656, 657, 658, 659, 660, 661, 662, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689, 690, 691, 692, 693, 694, 695, 696, 697, 698, 699, 700, 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, 720, 721, 722, 723, 724, 725, 726, 727, 728, 729, 730, 731, 732, 733, 734, 735, 736, 737, 738, 739, 740, 741, 742, 743, 744, 745, 746, 747, 748, 749, 750, 751, 752, 753, 754, 755, 756, 757, 758, 759, 760, 761, 762, 763, 764, 765, 766, 767, 768, 769, 770, 771, 772, 773, 774, 775, 776, 777, 778, 779, 780, 781, 782, 783, 784, 785, 786, 787, 788, 789, 790, 791, 792, 793, 794, 795, 796, 797, 798, 799, 800, 801, 802, 803, 804, 805, 806, 807, 808, 809, 810, 811, 812, 813, 814, 815, 816, 817, 818, 819, 820, 821, 822, 823, 824, 825, 826, 827, 828, 829, 830, 831, 832, 833, 834, 835, 836, 837, 838, 839, 840, 841, 842, 843, 844, 845, 846, 847, 848, 849, 850, 851, 852, 853, 854, 855, 856, 857, 858, 859, 860, 861, 862, 863, 864, 865, 866, 867, 868, 869, 870, 871, 872, 873, 874, 875, 876, 877, 878, 879, 880, 881, 882, 883, 884, 885, 886, 887, 888, 889, 890, 891, 892, 893, 894, 895, 896, 897, 898, 899, 900, 901, 902, 903, 904, 905, 906, 907, 908, 909, 910, 911, 912, 913, 914, 915, 916, 917, 918, 919, 920, 921, 922, 923, 924, 925, 926, 927, 928, 929, 930, 931, 932, 933, 934, 935, 936, 937, 938, 939, 940, 941, 942, 943, 944, 945, 946, 947, 948, 949, 950, 951, 952, 953, 954, 955, 956, 957, 958, 959, 960, 961, 962, 963, 964, 965, 966, 967, 968, 969, 970, 971, 972, 973, 974, 975, 976, 977, 978, 979, 980, 981, 982, 983, 984, 985, 986, 987, 988, 989, 990, 991, 992, 993, 994, 995, 996, 997, 998, 999]

In [18]:

    

b = np.array([[0,1,2],[3,4,5]])
b


    

    
Out[18]:





array([[0, 1, 2],
       [3, 4, 5]])

In [21]:

    

c = np.array([[[1,2], [3,4]], [[5,6], [7,8]]])


    

In [22]:

    

c


    

    
Out[22]:





array([[[1, 2],
        [3, 4]],

       [[5, 6],
        [7, 8]]])

In [23]:

    

print(c.ndim)


    

    




3

In [24]:

    

print(c.shape)


    

    




(2, 2, 2)

In [25]:

    

print(b.shape)


    

    




(2, 3)

In [26]:

    

a = np.array([[0, 1, 2, 3], [4, 5, 6, 7]])
a


    

    
Out[26]:





array([[0, 1, 2, 3],
       [4, 5, 6, 7]])

In [27]:

    

a[0, :]


    

    
Out[27]:





array([0, 1, 2, 3])

In [29]:

    

a[:, 1]


    

    
Out[29]:





array([1, 5])

In [30]:

    

a [ a % 2 == 0 ]


    

    
Out[30]:





array([0, 2, 4, 6])

In [31]:

    

# 뒤 함수에서 True라고 나온 친구들만 뽑음


    

In [37]:

    

a[np.array([0, 0])]


    

    
Out[37]:





array([[0, 1, 2, 3],
       [0, 1, 2, 3]])

In [36]:

    

a


    

    
Out[36]:





array([[0, 1, 2, 3],
       [4, 5, 6, 7]])

In [ ]:

    




    

In [ ]:

    




    

In [38]:

    

a = np.zeros(5)


    

In [39]:

    

a


    

    
Out[39]:





array([ 0.,  0.,  0.,  0.,  0.])

In [40]:

    

a1 = np.zeros((3,3))
a1


    

    
Out[40]:





array([[ 0.,  0.,  0.],
       [ 0.,  0.,  0.],
       [ 0.,  0.,  0.]])

In [43]:

    

a2 = np.ones((2,2))
a2


    

    
Out[43]:





array([[ 1.,  1.],
       [ 1.,  1.]])

In [45]:

    

a3 = np.ones_like(a1) # np.zeros_like
a3


    

    
Out[45]:





array([[ 1.,  1.,  1.],
       [ 1.,  1.,  1.],
       [ 1.,  1.,  1.]])

In [46]:

    

np.random.rand(3)


    

    
Out[46]:





array([ 0.85633064,  0.88401538,  0.72802139])

In [48]:

    

np.random.rand(3,3)


    

    
Out[48]:





array([[ 0.23801462,  0.0053857 ,  0.91720783],
       [ 0.83097621,  0.28630911,  0.8901733 ],
       [ 0.08814247,  0.10486478,  0.79840918]])

In [49]:

    

g = np.empty((4,3))
g


    

    
Out[49]:





array([[ 0.,  0.,  0.],
       [ 0.,  0.,  0.],
       [ 0.,  0.,  0.],
       [ 0.,  0.,  0.]])

In [52]:

    

np.linspace(0, 10, 5) # start, end, 간격


    

    
Out[52]:





array([  0. ,   2.5,   5. ,   7.5,  10. ])

In [53]:

    

np.random.seed(0)


    

In [54]:

    

np.random.rand(4)


    

    
Out[54]:





array([ 0.5488135 ,  0.71518937,  0.60276338,  0.54488318])

In [55]:

    

np.random.randn(4) # 가우시안 정규분포


    

    
Out[55]:





array([ 1.86755799, -0.97727788,  0.95008842, -0.15135721])

In [56]:

    

a = np.arange(12)


    

In [57]:

    

a.reshape(3,4)


    

    
Out[57]:





array([[ 0,  1,  2,  3],
       [ 4,  5,  6,  7],
       [ 8,  9, 10, 11]])

In [60]:

    

b = a.reshape(2,2,-1)
b


    

    
Out[60]:





array([[[ 0,  1,  2],
        [ 3,  4,  5]],

       [[ 6,  7,  8],
        [ 9, 10, 11]]])

In [61]:

    

b.flatten()


    

    
Out[61]:





array([ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11])

In [62]:

    

x = np.arange(5)
x


    

    
Out[62]:





array([0, 1, 2, 3, 4])

In [63]:

    

y = x.reshape(5,1)
y


    

    
Out[63]:





array([[0],
       [1],
       [2],
       [3],
       [4]])

In [64]:

    

z = x[:, np.newaxis]
z


    

    
Out[64]:





array([[0],
       [1],
       [2],
       [3],
       [4]])

In [65]:

    

a1 = np.ones((2,3))
a2 = np.zeros((2,2))


    

In [66]:

    

a1


    

    
Out[66]:





array([[ 1.,  1.,  1.],
       [ 1.,  1.,  1.]])

In [67]:

    

a2


    

    
Out[67]:





array([[ 0.,  0.],
       [ 0.,  0.]])

In [68]:

    

np.hstack([a1,a2])


    

    
Out[68]:





array([[ 1.,  1.,  1.,  0.,  0.],
       [ 1.,  1.,  1.,  0.,  0.]])

In [71]:

    

a3 = np.zeros((4,3))
a3


    

    
Out[71]:





array([[ 0.,  0.,  0.],
       [ 0.,  0.,  0.],
       [ 0.,  0.,  0.],
       [ 0.,  0.,  0.]])

In [72]:

    

np.vstack([a1,a3])


    

    
Out[72]:





array([[ 1.,  1.,  1.],
       [ 1.,  1.,  1.],
       [ 0.,  0.,  0.],
       [ 0.,  0.,  0.],
       [ 0.,  0.,  0.],
       [ 0.,  0.,  0.]])

In [73]:

    

# dstack은 축 방향으로 이동
# stack은 aixs 인수 사용 axis=0 행, axis=1 열


    

In [74]:

    

# r_ 메서드는 hstack과 유사한데 메서드임에도 불구하고 소괄호()를 사용하지 않고 대괄호 사용
np.r_[np.array([1,2,3]), 0, 0, np.array([4,3,5])]


    

    
Out[74]:





array([1, 2, 3, 0, 0, 4, 3, 5])

In [75]:

    

a = np.array([0, 1, 2])
np.tile(a, 2)


    

    
Out[75]:





array([0, 1, 2, 0, 1, 2])

In [2]:

    

x = np.arange(3)
x

y = np.arange(5)
y


    

    
Out[2]:





array([0, 1, 2, 3, 4])

In [3]:

    

X, Y = np.meshgrid(x, y)


    

In [97]:

    

for x, y in zip(X, Y):
    print(x, y)


    

    




[0 1 2] [0 0 0]
[0 1 2] [1 1 1]
[0 1 2] [2 2 2]
[0 1 2] [3 3 3]
[0 1 2] [4 4 4]

In [5]:

    

[list(zip(x, y)) for x, y in zip(X, Y)]


    

    
Out[5]:





[[(0, 0), (1, 0), (2, 0)],
 [(0, 1), (1, 1), (2, 1)],
 [(0, 2), (1, 2), (2, 2)],
 [(0, 3), (1, 3), (2, 3)],
 [(0, 4), (1, 4), (2, 4)]]

In [6]:

    

np.diag([1,2,3])


    

    
Out[6]:





array([[1, 0, 0],
       [0, 2, 0],
       [0, 0, 3]])

In [7]:

    

np.identity(3)


    

    
Out[7]:





array([[ 1.,  0.,  0.],
       [ 0.,  1.,  0.],
       [ 0.,  0.,  1.]])

In [8]:

    

np.eye(4)


    

    
Out[8]:





array([[ 1.,  0.,  0.,  0.],
       [ 0.,  1.,  0.,  0.],
       [ 0.,  0.,  1.,  0.],
       [ 0.,  0.,  0.,  1.]])

In [9]:

    

X = np.array([[11,12,13],[21,22,23]])
X


    

    
Out[9]:





array([[11, 12, 13],
       [21, 22, 23]])

In [10]:

    

X.T


    

    
Out[10]:





array([[11, 21],
       [12, 22],
       [13, 23]])

In [ ]: