在python中对数组的几个元素执行函数

Question

我有一个名为population的数组，其中包含66项，我想对每个元素执行log10，并将答案显示为一个数组。下面是我已经想到的：

import math
import numpy as np

population_magnitudes = math.log10(population.item(np.arange(0,66,1)))
population_magnitudes

我得到以下错误：

incorrect number of indices for array

有人能帮忙吗？你知道吗

Answer 1

示例：

from math import log
population = [2,4,23,4]
result = [log(val, 10) for val in population]

print result 


#output [0.30102999566398114, 0.6020599913279623, 1.3617278360175928, 0.6020599913279623]

Answer 2

MAP函数

可以使用map函数将函数应用于数组中的所有元素，如下所示：

>>> import math
>>> arr = [10**x for x in range(10)]
>>> arr
[1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000]
>>> ans = list(map(math.log10,arr))
>>> ans
[0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]

列表理解

可以使用此方法使用另一个列表迭代创建列表

>>> licomp = [math.log10(x) for x in arr]
>>> licomp
[0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]

如果您特别想要numpy数组，请使用np.log10而不是math.log10直接实现。否则，您可以按照上面的任何方法，然后使用np.array(list_obtained)将获得的列表转换为numpy数组。你知道吗

>>> import numpy as np
>>> nparr =  np.arange(66)
>>> nparr
array([ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16,
       17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33,
       34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
       51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65])
>>> np.log10(nparr)
__main__:1: RuntimeWarning: divide by zero encountered in log10
array([      -inf, 0.        , 0.30103   , 0.47712125, 0.60205999,
       0.69897   , 0.77815125, 0.84509804, 0.90308999, 0.95424251,
       1.        , 1.04139269, 1.07918125, 1.11394335, 1.14612804,
       1.17609126, 1.20411998, 1.23044892, 1.25527251, 1.2787536 ,
       1.30103   , 1.32221929, 1.34242268, 1.36172784, 1.38021124,
       1.39794001, 1.41497335, 1.43136376, 1.44715803, 1.462398  ,
       1.47712125, 1.49136169, 1.50514998, 1.51851394, 1.53147892,
       1.54406804, 1.5563025 , 1.56820172, 1.5797836 , 1.59106461,
       1.60205999, 1.61278386, 1.62324929, 1.63346846, 1.64345268,
       1.65321251, 1.66275783, 1.67209786, 1.68124124, 1.69019608,
       1.69897   , 1.70757018, 1.71600334, 1.72427587, 1.73239376,
       1.74036269, 1.74818803, 1.75587486, 1.76342799, 1.77085201,
       1.77815125, 1.78532984, 1.79239169, 1.79934055, 1.80617997,
       1.81291336])

Answer 3

我不确定我是否理解正确，但这能回答你的问题吗？你知道吗

import numpy as np

population = np.arange(0,66,1)
population_magnitudes = np.log10(population)
print(population_magnitudes)

输出：

[       -inf  0.          0.30103     0.47712125  0.60205999  0.69897
  0.77815125  0.84509804  0.90308999  0.95424251  1.          1.04139269
  1.07918125  1.11394335  1.14612804  1.17609126  1.20411998  1.23044892
  1.25527251  1.2787536   1.30103     1.32221929  1.34242268  1.36172784
  1.38021124  1.39794001  1.41497335  1.43136376  1.44715803  1.462398
  1.47712125  1.49136169  1.50514998  1.51851394  1.53147892  1.54406804
  1.5563025   1.56820172  1.5797836   1.59106461  1.60205999  1.61278386
  1.62324929  1.63346846  1.64345268  1.65321251  1.66275783  1.67209786
  1.68124124  1.69019608  1.69897     1.70757018  1.71600334  1.72427587
  1.73239376  1.74036269  1.74818803  1.75587486  1.76342799  1.77085201
  1.77815125  1.78532984  1.79239169  1.79934055  1.80617997  1.81291336]