我有一个数字列表，我想取当前值和以前值之间的差

Question

我有一个小数组，我想获取当前值和上一个值之间的差异，但我的数组以 1 开头。但我不希望出现 1 - 5。我希望数据集以原始值开始和结束：

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


diff = list()
one_year = 1
for i in range(0,len(x)):
    value = x[i] - x[i - one_year] #subtract current year with year before
    #print(x[i-one_year])
    print(value)
    diff.append(value)

print(diff)

-4
1
1
1
1

我希望数据以 1 开头，而不是 -4。 如何解决这个 for 循环？

Answer 1

你可以用这个：

x = np.array([1,2,3,4,5])
print(np.diff(x)) #==> 1, 1, 1, 1

Answer 2

试试这个：

import numpy as np

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

diff = [1]
one_year = 1
for i in range(1,len(x)):
    value = x[i] - x[i - one_year] #subtract current year with year before
    #print(x[i-one_year])
    print(value)
    diff.append(value)

print(diff)