[英]Adding a value to the first index of a list of array by using a list comprehension Python
The Vals list comprehension below modifies Values
such that for the number of nth rows it indexes the array values as such.下面的 Vals 列表理解修改了
Values
,以便对于第 n 行它索引数组值。 How would I be able to add an increment to the Vals
list comprehension where it adds 100 in front of all of the modified lists?我如何能够在
Vals
列表理解中添加一个增量,它在所有修改后的列表前面添加 100? I want to only modify the list comprehension function to do that.我只想修改列表理解 function 来做到这一点。
import numpy as np
first_index_val = 100
Values = np.array([[130,123,135.3,139.05,156.08,163.88,173.72],
[130,123,135.3,139.05,156.08,163.88,173.72],
[130,123,135.3,139.05,156.08,163.88,173.72],
[130,123,135.3,139.05,156.08,163.88,173.72],
[130,123,135.3,139.05,156.08,163.88,173.72],
[130,123,135.3,139.05,156.08,163.88,173.72],
[130,123,135.3,139.05,156.08,163.88,173.72]])
Vals = np.array([arr[i:] for i,arr in enumerate(Values.tolist())])
Output: Output:
[list([130.0, 123.0, 135.3, 139.05, 156.08, 163.88, 173.72])
list([123.0, 135.3, 139.05, 156.08, 163.88, 173.72])
list([135.3, 139.05, 156.08, 163.88, 173.72])
list([139.05, 156.08, 163.88, 173.72]) list([156.08, 163.88, 173.72])
list([163.88, 173.72]) list([173.72])]
Expected Output:预期 Output:
[list([100, 130.0, 123.0, 135.3, 139.05, 156.08, 163.88, 173.72])
list([100, 123.0, 135.3, 139.05, 156.08, 163.88, 173.72])
list([100, 135.3, 139.05, 156.08, 163.88, 173.72])
list([100, 139.05, 156.08, 163.88, 173.72]) list([100, 156.08, 163.88, 173.72])
list([100, 163.88, 173.72]) list([100, 173.72])]
Just add in the addition to the list comprehension.只需添加到列表理解中。
Vals = np.array([100] + [arr[i:] for i,arr in enumerate(Values.tolist())])
Here is my take on it, simple and declarative.这是我的看法,简单而明确。
import numpy as np
first_index_val = 100
values = np.array([[130, 123, 135.3, 139.05, 156.08, 163.88, 173.72],
[130, 123, 135.3, 139.05, 156.08, 163.88, 173.72],
[130, 123, 135.3, 139.05, 156.08, 163.88, 173.72],
[130, 123, 135.3, 139.05, 156.08, 163.88, 173.72],
[130, 123, 135.3, 139.05, 156.08, 163.88, 173.72],
[130, 123, 135.3, 139.05, 156.08, 163.88, 173.72],
[130, 123, 135.3, 139.05, 156.08, 163.88, 173.72]])
flipped = np.flip(values, 1)
appended = np.array([np.append(x, first_index_val) for x in flipped])
print(np.flip(appended, 1))
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