假设N = 7。因此，我的初始矩阵X将为7x6，我想创建一个大小为8x6的Y矩阵。
在这里，我想放置一个循环，使其选择第8行，找到| Y.T@Y |，然后将第8行替换为第9行，找到| Y.T@Y |。等等..对于其余的数据集。最终的Y矩阵将是8x6，具有最大| Y.T@Y |的第八行。从其余的数据集中
第一列是索引“ ID”。我也想显示Y的索引。
import pandas as pd
import numpy as np
import io
data = '''
ID,M,N,O,P,Q,R
5362,0.974,-0.404,-0.763,0.868,-0.5,0.16
485,-0.659,0.531,0.623,0.402,0.772,0.506
582,0.045,0.994,0.762,-0.036,0.117,-0.355
99,0.777,0.537,0.391,0.456,0.329,0.108
75,-0.44,0.522,0.856,-0.04,0.656,-0.935
474,0.357,0.81,0.135,0.389,0.055,0.224
594,-0.291,0.031,0.742,-0.332,0.815,0.983
597,0.968,-0.357,0.591,0.892,0.375,0.88
124,0.737,0.611,0.764,0.289,0.298,-0.705
635,0.883,0.96,-0.987,0.29,0.997,0.186
7894,-0.045,0.047,0.523,0.068,-0.9,0.356
1268,0.561,0.736,-0.375,0.465,0.908,0.2
38,0.465,0.623,0.734,0.145,0.489,0.759
88,0.029,0.166,0.098,0.285,0.18,0.829
887,0.464,0.652,-0.896,0.07,0.772,-0.268
994,-0.611,0.986,0.708,-0.195,0.938,0.166
478,0.109,0.664,0.977,0.2,-0.466,0.676
693,0.893,0.536,0.827,0,0.658,-0.31
455,0.745,0.851,0.025,0.667,0.094,0.127
874,0.036,-0.212,0.879,0.966,0.788,0.719
417,0.316,0.553,0.872,-0.274,0.946,0.238
44,0.517,-0.113,0.992,0.521,0.595,0.674
101,0.699,0.095,0.269,0.628,-0.711,-0.141
60,0.993,0.348,-0.44,0.807,0.013,0.325
8741,-0.319,0.535,0.717,-0.89,0.334,0.279
9635,0.363,0.812,0.77,0.715,0.34,0.327
2563,0.649,-0.788,0.405,0.056,0.25,0.08
5463,0.491,0.414,0.084,0.173,0.397,-0.499
1044,-0.669,0.288,0.424,-0.324,0.491,-0.581
999,0.208,0.082,-0.425,0.916,0.582,0.45
'''
df = pd.read_csv(io.StringIO(data),index_col=0)
M = df.iloc[:,:]
L = len(df.columns)
N = int(input( 'No. of rows for matrix: ' ))
if (N<L):
print("Error Occured.")
else:
X = M.iloc[0 : N ,:]
P = np.dot(X.T,X)
result = np.linalg.cond(P)
print("Condition number of matrix:")
print(result)
我曾尝试创建Y矩阵，但它仅占用下一行。我想将其放入循环并检查| Y.T@Y |通过将每一行一个接一个地添加到我的初始X矩阵中，并返回det | Y.T @ Y |的最大值的Y矩阵。
Y = M.iloc[0 : N+1 ,:]
Q = np.dot(Y.T,Y)
det1 = np.linalg.det(Q)
print("\nDeterminant of |Y.T@Y| : ",det1)
result1 = np.linalg.cond(Q)
print("\nCondition number of matrix Q : ", result1)
最佳答案
有趣的问题。要将代码放入循环中，您只需索引稍有不同即可。您可以使用逗号分隔的列表作为第一个索引。类似于[0, ..., N-1, last_row]。 range(N)或等效的0:N将为您提供嵌套列表，但您可以使用*运算符将其解压缩。
In [17]: for last_row in range(N, len(M)):
...: Y = M.iloc[[*range(N), last_row] ,:]
...: Q = np.dot(Y.T,Y)
...: det1 = np.linalg.det(Q)
...: print("\nDeterminant of |Y.T@Y| : ",det1)
...: result1 = np.linalg.cond(Q)
...: print("\nCondition number of matrix Q : ", result1)
...:
Determinant of |Y.T@Y| : 4.624339160318527
Condition number of matrix Q : 77.36824220530482
Determinant of |Y.T@Y| : 0.9409090804611786
Condition number of matrix Q : 263.91293535163385
Determinant of |Y.T@Y| : 33.03686043392585
Condition number of matrix Q : 16.581346840200407
Determinant of |Y.T@Y| : 12.63729785336232
Condition number of matrix Q : 22.538552279445806
Determinant of |Y.T@Y| : 12.263181714746796
Condition number of matrix Q : 17.66370953358896
Determinant of |Y.T@Y| : 0.7123582600048612
Condition number of matrix Q : 281.44289604007963
Determinant of |Y.T@Y| : 0.5339137593174599
Condition number of matrix Q : 257.90179496090224
Determinant of |Y.T@Y| : 23.995506419439238
Condition number of matrix Q : 16.575874347379973
Determinant of |Y.T@Y| : 2.253693250568694
Condition number of matrix Q : 91.90731212411028
Determinant of |Y.T@Y| : 10.651328369043002
Condition number of matrix Q : 29.76877614410439
Determinant of |Y.T@Y| : 1.2970342066212042
Condition number of matrix Q : 269.1794726321578
Determinant of |Y.T@Y| : 0.9369419026433131
Condition number of matrix Q : 169.53229478788683
Determinant of |Y.T@Y| : 4.651161625943493
Condition number of matrix Q : 81.67535737177332
Determinant of |Y.T@Y| : 1.5506338931653931
Condition number of matrix Q : 177.70943680087242
Determinant of |Y.T@Y| : 4.279015451906647
Condition number of matrix Q : 75.61213665437202
Determinant of |Y.T@Y| : 6.711423504463288
Condition number of matrix Q : 21.1381271541492
Determinant of |Y.T@Y| : 1.4394193359597567
Condition number of matrix Q : 120.40054369027756
Determinant of |Y.T@Y| : 0.8395233498254766
Condition number of matrix Q : 307.60761120624073
Determinant of |Y.T@Y| : 1.539364214268676
Condition number of matrix Q : 114.34947167985221
Determinant of |Y.T@Y| : 2.4774355106941384
Condition number of matrix Q : 144.27102186810066
Determinant of |Y.T@Y| : 2.2023866036448174
Condition number of matrix Q : 69.51903280436987
Determinant of |Y.T@Y| : 0.8649208511848647
Condition number of matrix Q : 175.3486680980588
Determinant of |Y.T@Y| : 2.841536699473401
Condition number of matrix Q : 85.79379870960514
我相信您会设法自己找出最大的矩阵：）