Basic_김신웅_1주차_1.ipynb

{"nbformat":4,"nbformat_minor":0,"metadata":{"colab":{"provenance":[],"authorship_tag":"ABX9TyPjuaSRGvpVqo96kQUha+lu"},"kernelspec":{"name":"python3","display_name":"Python 3"},"language_info":{"name":"python"}},"cells":[{"cell_type":"markdown","source":["# 넘파이\n","# Numpy ndarray 개요"],"metadata":{"id":"zAt_izChTGS1"}},{"cell_type":"code","execution_count":1,"metadata":{"id":"qANwm-rhSzlp","executionInfo":{"status":"ok","timestamp":1710123458442,"user_tz":-540,"elapsed":8,"user":{"displayName":"김신웅","userId":"06443905014267184666"}}},"outputs":[],"source":["import numpy as np"]},{"cell_type":"code","source":["array1 = np.array([1,2,3])\n","print('array1 type:',type(array1))\n","print('array1 array 형태:',array1.shape)\n","\n","array2 = np.array([[1,2,3],\n","                  [2,3,4]])\n","print('array2 type:',type(array2))\n","print('array2 array 형태:',array2.shape)\n","\n","array3 = np.array([[1,2,3]])\n","print('array3 type:',type(array3))\n","print('array3 array 형태:',array3.shape)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"VdqWURClTF6m","executionInfo":{"status":"ok","timestamp":1710123464048,"user_tz":-540,"elapsed":326,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"c6851a22-e9dd-49a8-baed-dc38d470946b"},"execution_count":2,"outputs":[{"output_type":"stream","name":"stdout","text":["array1 type: <class 'numpy.ndarray'>\n","array1 array 형태: (3,)\n","array2 type: <class 'numpy.ndarray'>\n","array2 array 형태: (2, 3)\n","array3 type: <class 'numpy.ndarray'>\n","array3 array 형태: (1, 3)\n"]}]},{"cell_type":"code","source":["print('array1: {0}차원, array2: {1}차원, array3: {2}차원'.format(array1.ndim,array2.ndim,array3.ndim))"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"uxADEyCGTdGh","executionInfo":{"status":"ok","timestamp":1710123507893,"user_tz":-540,"elapsed":292,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"b06dbebf-531d-489d-bae0-a94a1af8281f"},"execution_count":3,"outputs":[{"output_type":"stream","name":"stdout","text":["array1: 1차원, array2: 2차원, array3: 2차원\n"]}]},{"cell_type":"code","source":["list1 = [1,2,3]\n","print(type(list1))\n","array1 = np.array(list1)\n","print(type(array1))\n","print(array1, array1.dtype)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"o18W-tFoTmhS","executionInfo":{"status":"ok","timestamp":1710123545011,"user_tz":-540,"elapsed":298,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"7d487452-bf1e-45e3-9252-7b4a6a7083f9"},"execution_count":4,"outputs":[{"output_type":"stream","name":"stdout","text":["<class 'list'>\n","<class 'numpy.ndarray'>\n","[1 2 3] int64\n"]}]},{"cell_type":"code","source":["list2 = [1, 2, 'test']\n","array2 = np.array(list2)\n","print(array2, array2.dtype)\n","\n","list3 = [1, 2, 3.0]\n","array3 = np.array(list3)\n","print(array3, array3.dtype)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"BFF15e70TvxI","executionInfo":{"status":"ok","timestamp":1710123583835,"user_tz":-540,"elapsed":754,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"dad1354d-5719-4adb-897b-35220b383501"},"execution_count":5,"outputs":[{"output_type":"stream","name":"stdout","text":["['1' '2' 'test'] <U21\n","[1. 2. 3.] float64\n"]}]},{"cell_type":"code","source":["array_int = np.array([1, 2, 3])\n","array_float = array_int.astype('float64')\n","print(array_float, array_float.dtype)\n","\n","array_int1= array_float.astype('int32')\n","print(array_int1, array_int1.dtype)\n","\n","array_float1 = np.array([1.1, 2.1, 3.1])\n","array_int2= array_float1.astype('int32')\n","print(array_int2, array_int2.dtype)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"P3whtvNVT5HJ","executionInfo":{"status":"ok","timestamp":1710123622561,"user_tz":-540,"elapsed":318,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"8f7adb09-100c-4a77-ca2d-b0fc253298d9"},"execution_count":6,"outputs":[{"output_type":"stream","name":"stdout","text":["[1. 2. 3.] float64\n","[1 2 3] int32\n","[1 2 3] int32\n"]}]},{"cell_type":"markdown","source":["ndarray를 편리하게 생성하기 - arange, zeros, ones"],"metadata":{"id":"oyw4AHzmUHC0"}},{"cell_type":"code","source":["sequence_array = np.arange(10)\n","print(sequence_array)\n","print(sequence_array.dtype, sequence_array.shape)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"bBpDx77zUIEz","executionInfo":{"status":"ok","timestamp":1710123703379,"user_tz":-540,"elapsed":308,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"3ac5ccfd-863b-469c-91d0-1a3c5661782c"},"execution_count":7,"outputs":[{"output_type":"stream","name":"stdout","text":["[0 1 2 3 4 5 6 7 8 9]\n","int64 (10,)\n"]}]},{"cell_type":"code","source":["zero_array = np.zeros((3,2),dtype='int32')\n","print(zero_array)\n","print(zero_array.dtype, zero_array.shape)\n","\n","one_array = np.ones((3,2))\n","print(one_array)\n","print(one_array.dtype, one_array.shape)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"nN_A6F6MUKNc","executionInfo":{"status":"ok","timestamp":1710123714246,"user_tz":-540,"elapsed":308,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"d175b255-fa63-4c1a-bd00-17899c2e63ea"},"execution_count":8,"outputs":[{"output_type":"stream","name":"stdout","text":["[[0 0]\n"," [0 0]\n"," [0 0]]\n","int32 (3, 2)\n","[[1. 1.]\n"," [1. 1.]\n"," [1. 1.]]\n","float64 (3, 2)\n"]}]},{"cell_type":"markdown","source":["reshape"],"metadata":{"id":"cz1RV-PRUfDE"}},{"cell_type":"code","source":["array1 = np.arange(10)\n","print('array1:\\n', array1)\n","\n","array2 = array1.reshape(2,5)\n","print('array2:\\n',array2)\n","\n","array3 = array1.reshape(5,2)\n","print('array3:\\n',array3)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"E5nkpecaUftG","executionInfo":{"status":"ok","timestamp":1710123783172,"user_tz":-540,"elapsed":321,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"aaed5f1f-fbe0-4224-da91-ad6fc415f497"},"execution_count":9,"outputs":[{"output_type":"stream","name":"stdout","text":["array1:\n"," [0 1 2 3 4 5 6 7 8 9]\n","array2:\n"," [[0 1 2 3 4]\n"," [5 6 7 8 9]]\n","array3:\n"," [[0 1]\n"," [2 3]\n"," [4 5]\n"," [6 7]\n"," [8 9]]\n"]}]},{"cell_type":"code","source":["array1.reshape(4,3) #사이즈 배수가 아니라서 reshape못함"],"metadata":{"colab":{"base_uri":"https://localhost:8080/","height":149},"id":"lzDUnnIRUlRd","executionInfo":{"status":"error","timestamp":1710123801862,"user_tz":-540,"elapsed":327,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"b58852e8-665f-4723-ffe2-d86e258a4400"},"execution_count":10,"outputs":[{"output_type":"error","ename":"ValueError","evalue":"cannot reshape array of size 10 into shape (4,3)","traceback":["\u001b[0;31m---------------------------------------------------------------------------\u001b[0m","\u001b[0;31mValueError\u001b[0m                                Traceback (most recent call last)","\u001b[0;32m<ipython-input-10-a40469ec5825>\u001b[0m in \u001b[0;36m<cell line: 1>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0marray1\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mreshape\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m4\u001b[0m\u001b[0;34m,\u001b[0m\u001b[0;36m3\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m","\u001b[0;31mValueError\u001b[0m: cannot reshape array of size 10 into shape (4,3)"]}]},{"cell_type":"code","source":["array1 = np.arange(10)\n","print(array1)\n","\n","array2 = array1.reshape(-1,5)   #-1의 의미는 적절한 사이즈로 reshape 하라는 뜻인듯\n","print(array2)\n","print('array2 shape:',array2.shape)\n","\n","print(array3)\n","array3 = array1.reshape(5,-1)  #위와 마찬가지\n","print('array3 shape:',array3.shape)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"cNpXGkbaUqC9","executionInfo":{"status":"ok","timestamp":1710123947316,"user_tz":-540,"elapsed":418,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"d2d3e3f6-79c4-4739-e4bd-e41d0b634f64"},"execution_count":12,"outputs":[{"output_type":"stream","name":"stdout","text":["[0 1 2 3 4 5 6 7 8 9]\n","[[0 1 2 3 4]\n"," [5 6 7 8 9]]\n","array2 shape: (2, 5)\n","[[0 1]\n"," [2 3]\n"," [4 5]\n"," [6 7]\n"," [8 9]]\n","array3 shape: (5, 2)\n"]}]},{"cell_type":"code","source":["array1 = np.arange(10)\n","array4 = array1.reshape(-1,4)  #적절한 배수가 아니면 ValueError 뜸"],"metadata":{"colab":{"base_uri":"https://localhost:8080/","height":168},"id":"eCmrKb0EVVxf","executionInfo":{"status":"error","timestamp":1710124000462,"user_tz":-540,"elapsed":314,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"b61112d5-db95-4ff9-917e-6b01e2389be8"},"execution_count":13,"outputs":[{"output_type":"error","ename":"ValueError","evalue":"cannot reshape array of size 10 into shape (4)","traceback":["\u001b[0;31m---------------------------------------------------------------------------\u001b[0m","\u001b[0;31mValueError\u001b[0m                                Traceback (most recent call last)","\u001b[0;32m<ipython-input-13-07da9760475e>\u001b[0m in \u001b[0;36m<cell line: 2>\u001b[0;34m()\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0marray1\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mnp\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0marange\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m10\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 2\u001b[0;31m \u001b[0marray4\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0marray1\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mreshape\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m-\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m\u001b[0;36m4\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m","\u001b[0;31mValueError\u001b[0m: cannot reshape array of size 10 into shape (4)"]}]},{"cell_type":"code","source":["array1 = np.arange(8)\n","array3d = array1.reshape((2,2,2))    #3차원으로 reshape\n","print('array3d:\\n',array3d.tolist())\n","\n","# 3차원 ndarray를 2차원 ndarray로 변환\n","array5 = array3d.reshape(-1,1)   #2차원이면서 원소개수가 1인\n","print('array5:\\n',array5.tolist())\n","print('array5 shape:',array5.shape)\n","\n","# 1차원 ndarray를 2차원 ndarray로 변환\n","array6 = array1.reshape(-1,1)\n","print('array6:\\n',array6.tolist())\n","print('array6 shape:',array6.shape)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"mdOq5nv9Vd-Z","executionInfo":{"status":"ok","timestamp":1710124034662,"user_tz":-540,"elapsed":323,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"bc9b0f33-5f8a-4534-debf-45442c52cce2"},"execution_count":14,"outputs":[{"output_type":"stream","name":"stdout","text":["array3d:\n"," [[[0, 1], [2, 3]], [[4, 5], [6, 7]]]\n","array5:\n"," [[0], [1], [2], [3], [4], [5], [6], [7]]\n","array5 shape: (8, 1)\n","array6:\n"," [[0], [1], [2], [3], [4], [5], [6], [7]]\n","array6 shape: (8, 1)\n"]}]},{"cell_type":"markdown","source":["**indexing**"],"metadata":{"id":"LxYcclM7WG9T"}},{"cell_type":"markdown","source":["- 단일값 추출"],"metadata":{"id":"_y4uD8TVWMPb"}},{"cell_type":"code","source":["# 1에서 부터 9 까지의 1차원 ndarray 생성\n","array1 = np.arange(start=1, stop=10)\n","print('array1:',array1)\n","# index는 0 부터 시작하므로 array1[2]는 3번째 index 위치의 데이터 값을 의미\n","value = array1[2]\n","print('value:',value)\n","print(type(value))"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"2u1jVDU_WJh6","executionInfo":{"status":"ok","timestamp":1710124340943,"user_tz":-540,"elapsed":312,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"f0e532e7-c3a6-42e1-8798-7c934d7b0c2b"},"execution_count":16,"outputs":[{"output_type":"stream","name":"stdout","text":["array1: [1 2 3 4 5 6 7 8 9]\n","value: 3\n","<class 'numpy.int64'>\n"]}]},{"cell_type":"code","source":["print('맨 뒤의 값:',array1[-1], ', 맨 뒤에서 두번째 값:',array1[-2])"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"GXNqukO4WyYA","executionInfo":{"status":"ok","timestamp":1710124380772,"user_tz":-540,"elapsed":411,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"fcf6c2da-5eed-490b-de14-455b73d0e545"},"execution_count":17,"outputs":[{"output_type":"stream","name":"stdout","text":["맨 뒤의 값: 9 , 맨 뒤에서 두번째 값: 8\n"]}]},{"cell_type":"code","source":["array1[0] = 9\n","array1[8] = 0\n","print('array1:',array1)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"rL165pt6W1mz","executionInfo":{"status":"ok","timestamp":1710124393598,"user_tz":-540,"elapsed":297,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"bd3672be-71c4-4aba-8a86-02486b7abdef"},"execution_count":18,"outputs":[{"output_type":"stream","name":"stdout","text":["array1: [9 2 3 4 5 6 7 8 0]\n"]}]},{"cell_type":"code","source":["array1d = np.arange(start=1, stop=10)\n","array2d = array1d.reshape(3,3)\n","print(array2d)\n","\n","print('(row=0,col=0) index 가리키는 값:', array2d[0,0] )\n","print('(row=0,col=1) index 가리키는 값:', array2d[0,1] )\n","print('(row=1,col=0) index 가리키는 값:', array2d[1,0] )\n","print('(row=2,col=2) index 가리키는 값:', array2d[2,2] )"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"UX9ppGJDW5GP","executionInfo":{"status":"ok","timestamp":1710124408832,"user_tz":-540,"elapsed":1027,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"88586eee-faad-4166-e9ca-dc8a136d79cb"},"execution_count":19,"outputs":[{"output_type":"stream","name":"stdout","text":["[[1 2 3]\n"," [4 5 6]\n"," [7 8 9]]\n","(row=0,col=0) index 가리키는 값: 1\n","(row=0,col=1) index 가리키는 값: 2\n","(row=1,col=0) index 가리키는 값: 4\n","(row=2,col=2) index 가리키는 값: 9\n"]}]},{"cell_type":"markdown","source":["- Slicing"],"metadata":{"id":"au4hrMPdW_pU"}},{"cell_type":"code","source":["array1 = np.arange(start=1, stop=10)\n","array3 = array1[0:3]\n","print(array3)\n","print(type(array3))"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"rbDPWLPWXAk2","executionInfo":{"status":"ok","timestamp":1710124443441,"user_tz":-540,"elapsed":310,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"6224b023-17e7-4cd7-8d35-01fdfcdd58f6"},"execution_count":20,"outputs":[{"output_type":"stream","name":"stdout","text":["[1 2 3]\n","<class 'numpy.ndarray'>\n"]}]},{"cell_type":"code","source":["array1 = np.arange(start=1, stop=10)\n","array4 = array1[:3]  #3까지 자르면 0부터 2까지 잘라져서 총 3개나옴\n","print(array4)\n","\n","array5 = array1[3:]  #3부터하면 인덱스 3부터 시작 (1, 2, 3, [4, 5, 6, 7, 8, 9])\n","print(array5)\n","\n","array6 = array1[:]  #전체의미\n","print(array6)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"cM5UR3RNXEyy","executionInfo":{"status":"ok","timestamp":1710124455452,"user_tz":-540,"elapsed":275,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"0fdf3db1-84be-4518-9c6a-86b4899d9efa"},"execution_count":21,"outputs":[{"output_type":"stream","name":"stdout","text":["[1 2 3]\n","[4 5 6 7 8 9]\n","[1 2 3 4 5 6 7 8 9]\n"]}]},{"cell_type":"code","source":["array1d = np.arange(start=1, stop=10)   #행렬 인덱싱\n","array2d = array1d.reshape(3,3)\n","print('array2d:\\n',array2d)\n","print('---------------------')\n","print('array2d[0:2, 0:2] \\n', array2d[0:2, 0:2])\n","print('---------------------')\n","print('array2d[1:3, 0:3] \\n', array2d[1:3, 0:3])\n","print('---------------------')\n","print('array2d[1:3, :] \\n', array2d[1:3, :])\n","print('---------------------')\n","print('array2d[:, :] \\n', array2d[:, :])\n","print('---------------------')\n","print('array2d[:2, 1:] \\n', array2d[:2, 1:])\n","print('---------------------')\n","print('array2d[:2, 0] \\n', array2d[:2, 0]) #얘는 1차원이 됐네"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"UcZ4uScOXtST","executionInfo":{"status":"ok","timestamp":1710124748494,"user_tz":-540,"elapsed":333,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"8f24ec6f-e271-4a4b-f2f8-52a3aec97963"},"execution_count":23,"outputs":[{"output_type":"stream","name":"stdout","text":["array2d:\n"," [[1 2 3]\n"," [4 5 6]\n"," [7 8 9]]\n","---------------------\n","array2d[0:2, 0:2] \n"," [[1 2]\n"," [4 5]]\n","---------------------\n","array2d[1:3, 0:3] \n"," [[4 5 6]\n"," [7 8 9]]\n","---------------------\n","array2d[1:3, :] \n"," [[4 5 6]\n"," [7 8 9]]\n","---------------------\n","array2d[:, :] \n"," [[1 2 3]\n"," [4 5 6]\n"," [7 8 9]]\n","---------------------\n","array2d[:2, 1:] \n"," [[2 3]\n"," [5 6]]\n","---------------------\n","array2d[:2, 0] \n"," [1 4]\n"]}]},{"cell_type":"code","source":["print(array2d[0])\n","print(array2d[1])\n","print('array2d[0] shape:', array2d[0].shape, 'array2d[1] shape:', array2d[1].shape )"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"tP9G9RvXY2TA","executionInfo":{"status":"ok","timestamp":1710124921081,"user_tz":-540,"elapsed":327,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"098e6186-174b-44b7-b864-b4079a5f77a1"},"execution_count":24,"outputs":[{"output_type":"stream","name":"stdout","text":["[1 2 3]\n","[4 5 6]\n","array2d[0] shape: (3,) array2d[1] shape: (3,)\n"]}]},{"cell_type":"markdown","source":["- fancy indexing"],"metadata":{"id":"GPFiKHOpY9YR"}},{"cell_type":"code","source":["array1d = np.arange(start=1, stop=10) #1부터 9까지 리스트 만들고\n","array2d = array1d.reshape(3,3)\n","print('array2d => ', array2d.tolist())\n","\n","\n","array3 = array2d[[0,1], 2]  #앞에 0행과 1행에서 2번째 인덱스 원소\n","print('array2d[[0,1], 2] => ',array3.tolist())\n","\n","array4 = array2d[[0,1], 0:2]\n","print('array2d[[0,1], 0:2] => ',array4.tolist())\n","\n","array5 = array2d[[0,1]]\n","print('array2d[[0,1]] => ',array5.tolist())"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"iR_9zthnY-EC","executionInfo":{"status":"ok","timestamp":1710125169248,"user_tz":-540,"elapsed":294,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"b83a982b-5825-418e-da9e-9e0f9fbc72d9"},"execution_count":27,"outputs":[{"output_type":"stream","name":"stdout","text":["array2d =>  [[1, 2, 3], [4, 5, 6], [7, 8, 9]]\n","array2d[[0,1], 2] =>  [3, 6]\n","array2d[[0,1], 0:2] =>  [[1, 2], [4, 5]]\n","array2d[[0,1]] =>  [[1, 2, 3], [4, 5, 6]]\n"]}]},{"cell_type":"markdown","source":["- Boolean indexing"],"metadata":{"id":"TKOTOcDyZBXU"}},{"cell_type":"code","source":["array1d = np.arange(start=1, stop=10)\n","# [ ] 안에 array1d > 5 Boolean indexing을 적용\n","array3 = array1d[array1d > 5]   #이런것도 되네 편리하다\n","print('array1d > 5 불린 인덱싱 결과 값 :', array3)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"N3pb6t3VZCIY","executionInfo":{"status":"ok","timestamp":1710125531842,"user_tz":-540,"elapsed":289,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"a77fb3d8-6aec-4c6b-f07a-988bada38547"},"execution_count":28,"outputs":[{"output_type":"stream","name":"stdout","text":["array1d > 5 불린 인덱싱 결과 값 : [6 7 8 9]\n"]}]},{"cell_type":"code","source":["array1d > 5"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"AlSa9gsObPcI","executionInfo":{"status":"ok","timestamp":1710125561042,"user_tz":-540,"elapsed":309,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"e7837ad7-8bd0-49a3-ad0e-6bb6586fce90"},"execution_count":30,"outputs":[{"output_type":"execute_result","data":{"text/plain":["array([False, False, False, False, False,  True,  True,  True,  True])"]},"metadata":{},"execution_count":30}]},{"cell_type":"code","source":["boolean_indexes = np.array([False, False, False, False, False,  True,  True,  True,  True])\n","array3 = array1d[boolean_indexes]\n","print('불린 인덱스로 필터링 결과 :', array3)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"vXthKmV5bVRB","executionInfo":{"status":"ok","timestamp":1710125577736,"user_tz":-540,"elapsed":412,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"33110b23-4661-4bee-f97b-cd86b211dfb0"},"execution_count":31,"outputs":[{"output_type":"stream","name":"stdout","text":["불린 인덱스로 필터링 결과 : [6 7 8 9]\n"]}]},{"cell_type":"code","source":["indexes = np.array([5,6,7,8])\n","array4 = array1d[ indexes ]   #인덱스를 list로 담아서 인덱스로 넣어도 해당 인덱스의 원소로 필터링 가능\n","print('일반 인덱스로 필터링 결과 :',array4)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"UIZCbV-GbbSo","executionInfo":{"status":"ok","timestamp":1710125596886,"user_tz":-540,"elapsed":415,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"d377b88c-1a7c-4f7f-c13b-ea98260b87b4"},"execution_count":32,"outputs":[{"output_type":"stream","name":"stdout","text":["일반 인덱스로 필터링 결과 : [6 7 8 9]\n"]}]},{"cell_type":"markdown","source":["# 행렬의 정렬 – sort( )와 argsort( )"],"metadata":{"id":"LSM7EJ2Hbm_J"}},{"cell_type":"markdown","source":["- 행렬 정렬"],"metadata":{"id":"Cq4yxdhFboqJ"}},{"cell_type":"code","source":["org_array = np.array([ 3, 1, 9, 5])\n","print('원본 행렬:', org_array)\n","# np.sort( )로 정렬\n","sort_array1 = np.sort(org_array)       #np.sort는 default가 오름차순으로 정렬하고 반환값으로 넘김  , 원본은 건들지 않음\n","print ('np.sort( ) 호출 후 반환된 정렬 행렬:', sort_array1)\n","print('np.sort( ) 호출 후 원본 행렬:', org_array)\n","# ndarray.sort( )로 정렬\n","sort_array2 = org_array.sort()         #ndarray.sort는 반환하는 값 없이 원본을 바로 바꿈  / 상황에 맞게 쓰기\n","print('org_array.sort( ) 호출 후 반환된 행렬:', sort_array2)\n","print('org_array.sort( ) 호출 후 원본 행렬:', org_array)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"YNfyoO4YbvRq","executionInfo":{"status":"ok","timestamp":1710125685673,"user_tz":-540,"elapsed":1033,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"85e99605-56ac-4b60-9c0f-72ad492592d3"},"execution_count":33,"outputs":[{"output_type":"stream","name":"stdout","text":["원본 행렬: [3 1 9 5]\n","np.sort( ) 호출 후 반환된 정렬 행렬: [1 3 5 9]\n","np.sort( ) 호출 후 원본 행렬: [3 1 9 5]\n","org_array.sort( ) 호출 후 반환된 행렬: None\n","org_array.sort( ) 호출 후 원본 행렬: [1 3 5 9]\n"]}]},{"cell_type":"code","source":["sort_array1_desc = np.sort(org_array)[::-1]  #reverse를 이런식으로 사용\n","print ('내림차순으로 정렬:', sort_array1_desc)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"mep5dUbncPfS","executionInfo":{"status":"ok","timestamp":1710125810508,"user_tz":-540,"elapsed":390,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"f85b42af-e217-48c3-d970-800305b84400"},"execution_count":34,"outputs":[{"output_type":"stream","name":"stdout","text":["내림차순으로 정렬: [9 5 3 1]\n"]}]},{"cell_type":"code","source":["array2d = np.array([[8, 12],\n","                   [7, 1 ]])\n","\n","sort_array2d_axis0 = np.sort(array2d, axis=0)     #행끼리 비교하면 [8,12] 와 [7,1] 을 비교하는데 7이 8보다 작아서 행이 앞으로 오게되었음\n","print('로우 방향으로 정렬:\\n', sort_array2d_axis0)\n","\n","sort_array2d_axis1 = np.sort(array2d, axis=1)     #열끼리 비교하면 첫번째 열은 [8,7] 이고 두번째 열은 [12,1]임 8은 12보다 작으므로 8, 12가 앞으로 오게됨\n","print('컬럼 방향으로 정렬:\\n', sort_array2d_axis1)  #맞는지 물어보면 좋겠다"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"fc71nOX2cedO","executionInfo":{"status":"ok","timestamp":1710125871420,"user_tz":-540,"elapsed":517,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"307da467-f315-47d1-e63c-a41d33a3be3f"},"execution_count":35,"outputs":[{"output_type":"stream","name":"stdout","text":["로우 방향으로 정렬:\n"," [[ 7  1]\n"," [ 8 12]]\n","컬럼 방향으로 정렬:\n"," [[ 8 12]\n"," [ 1  7]]\n"]}]},{"cell_type":"markdown","source":["- 정렬 행렬의 인덱스 반환"],"metadata":{"id":"1H3q8imddAvW"}},{"cell_type":"code","source":["org_array = np.array([ 3, 1, 9, 5])\n","sort_indices = np.argsort(org_array)   #np.argsort는 정렬한 리스트의 인덱스 순서를 리스트로 반환해준다.(알고리즘 할 때도 써먹을 수 있을듯)\n","print(type(sort_indices))\n","print('행렬 정렬 시 원본 행렬의 인덱스:', sort_indices)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"mI0yPRQydC8M","executionInfo":{"status":"ok","timestamp":1710126591336,"user_tz":-540,"elapsed":284,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"0cef5a48-8ecb-4ee5-c40c-fbf8a2cf78a8"},"execution_count":37,"outputs":[{"output_type":"stream","name":"stdout","text":["<class 'numpy.ndarray'>\n","행렬 정렬 시 원본 행렬의 인덱스: [1 0 3 2]\n"]}]},{"cell_type":"code","source":["org_array = np.array([ 3, 1, 9, 5])\n","sort_indices_desc = np.argsort(org_array)[::-1]   #이번엔 원소가 큰 순서대로 인덱스를 반환\n","print('행렬 내림차순 정렬 시 원본 행렬의 인덱스:', sort_indices_desc)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"hlzdQma5flT3","executionInfo":{"status":"ok","timestamp":1710126685971,"user_tz":-540,"elapsed":361,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"bf3efd49-068a-4570-bc5b-92264f191dd9"},"execution_count":38,"outputs":[{"output_type":"stream","name":"stdout","text":["행렬 내림차순 정렬 시 원본 행렬의 인덱스: [2 3 0 1]\n"]}]},{"cell_type":"code","source":["import numpy as np\n","\n","name_array = np.array(['John', 'Mike', 'Sarah', 'Kate', 'Samuel'])\n","score_array= np.array([78, 95, 84, 98, 88])\n","\n","sort_indices_asc = np.argsort(score_array)   #성적 낮은순서로 인덱스를 뽑기\n","print('성적 오름차순 정렬 시 score_array의 인덱스:', sort_indices_asc)\n","print('성적 오름차순으로 name_array의 이름 출력:', name_array[sort_indices_asc]) #그대로 name_array의 인덱스로 활용해서 순서대로 뽑기 (내부적으로 iterate하는듯)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"e5bKly0uf1do","executionInfo":{"status":"ok","timestamp":1710126755489,"user_tz":-540,"elapsed":289,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"9b9a2195-ecf2-4626-f948-9e1889eb8503"},"execution_count":39,"outputs":[{"output_type":"stream","name":"stdout","text":["성적 오름차순 정렬 시 score_array의 인덱스: [0 2 4 1 3]\n","성적 오름차순으로 name_array의 이름 출력: ['John' 'Sarah' 'Samuel' 'Mike' 'Kate']\n"]}]},{"cell_type":"markdown","source":["# 선형대수 연산 – 행렬 내적과 전치 행렬 구하기"],"metadata":{"id":"MT8FY9aegjK1"}},{"cell_type":"markdown","source":["- 행렬 내적"],"metadata":{"id":"HUAEIZdOgnM-"}},{"cell_type":"code","source":["A = np.array([[1, 2, 3],\n","              [4, 5, 6]])\n","B = np.array([[7, 8],\n","              [9, 10],\n","              [11, 12]])\n","\n","dot_product = np.dot(A, B)  # (2x3)이랑 (3x2) 했으니까 (2x2) 행렬로 나와야함  np.dot이 내적\n","print('행렬 내적 결과:\\n', dot_product)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"yTpapRyjgl0A","executionInfo":{"status":"ok","timestamp":1710126992509,"user_tz":-540,"elapsed":279,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"0cc70d85-8855-419f-e72a-42255db45ce7"},"execution_count":40,"outputs":[{"output_type":"stream","name":"stdout","text":["행렬 내적 결과:\n"," [[ 58  64]\n"," [139 154]]\n"]}]},{"cell_type":"markdown","source":["- 전치 행렬"],"metadata":{"id":"SYv4h3SpgqQJ"}},{"cell_type":"code","source":["A = np.array([[1, 2],\n","              [3, 4]])\n","transpose_mat = np.transpose(A)     # A^T 구하기\n","print('A의 전치 행렬:\\n', transpose_mat)"],"metadata":{"colab":{"base_uri":"https://localhost:8080/"},"id":"UbV0PtU9gv1W","executionInfo":{"status":"ok","timestamp":1710126995687,"user_tz":-540,"elapsed":399,"user":{"displayName":"김신웅","userId":"06443905014267184666"}},"outputId":"dfc12b6c-d483-456d-918e-764c9b3a5d54"},"execution_count":41,"outputs":[{"output_type":"stream","name":"stdout","text":["A의 전치 행렬:\n"," [[1 3]\n"," [2 4]]\n"]}]}]}