【NumPy】リスト内の隣り合う要素の差分を計算する方法（np.diff）[Python]

import numpy as np

a = [1, 2, 3, 5, 7, 11, 13]

print(np.diff(a))

実行結果
[1 1 2 2 4 2]

import numpy as np

b = [[1, 2, 3, 4, 5],
     [3, 4, 5, 6, 7],
     [6, 7, 8, 9, 10]]

print(np.diff(b))

実行結果
[[1 1 1 1]
 [1 1 1 1]
 [1 1 1 1]]

import numpy as np

b = [[1, 2, 3, 4, 5],
     [3, 4, 5, 6, 7],
     [6, 7, 8, 9, 10]]

print(np.diff(b, axis=0))

実行結果
[[2 2 2 2 2]
 [3 3 3 3 3]]

import numpy as np

b = [[1, 2, 3, 4, 5],
     [3, 4, 5, 6, 7],
     [6, 7, 8, 9, 10]]

print(np.diff(b, axis=1))

実行結果
[[1 1 1 1]
 [1 1 1 1]
 [1 1 1 1]]

import numpy as np

c = [[[1, 2, 3], [2, 3, 4], [3, 4, 5]],
     [[3, 4, 5], [5, 6, 7], [7, 8, 9]],
     [[6, 7, 8], [9, 10, 11], [12, 13, 14]]]

print(np.diff(c, axis=0))

実行結果
[[[2 2 2]
  [3 3 3]
  [4 4 4]]

 [[3 3 3]
  [4 4 4]
  [5 5 5]]]

import numpy as np

c = [[[1, 2, 3], [2, 3, 4], [3, 4, 5]],
     [[3, 4, 5], [5, 6, 7], [7, 8, 9]],
     [[6, 7, 8], [9, 10, 11], [12, 13, 14]]]

print(np.diff(c, axis=1))

実行結果
[[[1 1 1]
  [1 1 1]]

 [[2 2 2]
  [2 2 2]]

 [[3 3 3]
  [3 3 3]]]

import numpy as np

c = [[[1, 2, 3], [2, 3, 4], [3, 4, 5]],
     [[3, 4, 5], [5, 6, 7], [7, 8, 9]],
     [[6, 7, 8], [9, 10, 11], [12, 13, 14]]]

print(np.diff(c, axis=2))

実行結果
[[[1 1]
  [1 1]
  [1 1]]

 [[1 1]
  [1 1]
  [1 1]]

 [[1 1]
  [1 1]
  [1 1]]]

import numpy as np

d = [1, 3, 6, 10, 15] 

print(np.diff(d, 1))
print(np.diff(d, 2))
print(np.diff(d, 3))

実行結果
[2 3 4 5]
[1 1 1]
[0 0]

import numpy as np

d = [1, 3, 6, 10, 15] 

print(np.diff(d, prepend=0))

実行結果
[1 2 3 4 5]

import numpy as np

d = [1, 3, 6, 10, 15] 

print(np.diff(d, append=21))

実行結果
[2 3 4 5 6]

import numpy as np

d = [1, 3, 6, 10, 15] 

print(np.diff(d, prepend=[3, 2, 1]))

実行結果
[-1 -1  0  2  3  4  5]

import numpy as np

d = [1, 3, 6, 10, 15] 

print(np.diff(d, append=[21, 20, 19]))

実行結果
[ 2  3  4  5  6 -1 -1]

import numpy as np

d = [1, 3, 6, 10, 15] 

print(np.diff(d, prepend=[[3, 2], [2, 1]]))

実行結果
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Cell In[8], line 5
      1 import numpy as np
      3 d = [1, 3, 6, 10, 15] 
----> 5 print(np.diff(d, prepend=[[3, 2], [2, 1]]))

File /Library/Frameworks/Python.framework/Versions/3.10/lib/
python3.10/site-packages/numpy/lib/function_base.py:1441, 
in diff(a, n, axis, prepend, append)
   1438     combined.append(append)
   1440 if len(combined) > 1:
-> 1441     a = np.concatenate(combined, axis)
   1443 slice1 = [slice(None)] * nd
   1444 slice2 = [slice(None)] * nd

ValueError: all the input arrays must have same number of 
dimensions, but the array at index 0 has 2 dimension(s) and 
the array at index 1 has 1 dimension(s)

import numpy as np

d = [1, 3, 6, 10, 15] 

print(np.diff(d, append=[[21, 20], [20, 19]]))

実行結果
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Cell In[9], line 5
      1 import numpy as np
      3 d = [1, 3, 6, 10, 15] 
----> 5 print(np.diff(d, append=[[21, 20], [20, 19]]))

File /Library/Frameworks/Python.framework/Versions/3.10/lib/
python3.10/site-packages/numpy/lib/function_base.py:1441, 
in diff(a, n, axis, prepend, append)
   1438     combined.append(append)
   1440 if len(combined) > 1:
-> 1441     a = np.concatenate(combined, axis)
   1443 slice1 = [slice(None)] * nd
   1444 slice2 = [slice(None)] * nd

ValueError: all the input arrays must have same number of 
dimensions, but the array at index 0 has 1 dimension(s) and 
the array at index 1 has 2 dimension(s)

import numpy as np

e = np.arange("2024-01-01", "2024-01-06", dtype=np.datetime64)

print(e)

print(np.diff(e))

実行結果
['2024-01-01' '2024-01-02' '2024-01-03' '2024-01-04' '2024-01-05']
[1 1 1 1]