如何在没有numpy的字典中创建一个交替值数组？答案

【问题标题】：How to create an array of alternating values inside a dictionary without numpy?如何在没有numpy的字典中创建一个交替值数组？
【发布时间】：2019-11-05 10:35:19
【问题描述】：

我有这本词典：

dict = {
    "A1": [round(f, prec) for vr in ex_vrs for f in vr.pos],
    "A2": []
      }

我希望 A2 有点像 "A2": [0,1,0,1, .... ] 长度 = len(A1)/3*2

有什么想法可以做到这一点吗？非常感谢

【问题讨论】：

标签： python arrays dictionary

【解决方案1】：

试试下面的。

# initialise the dictionary with the A1 entry
dict = {"A1" : [round(f, prec) for vr in ex_vrs for f in vr.pos]}

# Determine length of the alternating list for the A2 entry
mylength = int(len(dict["A1"])/3*2)

# Use mod operator to determine (un)even numbers for the alternating list
dict["A2"] = [i % 2 for i in range(mylength + 1)]

如果你想要字符串而不是数字来交替：

# initialise the dictionary with the A1 entry
dict = {"A1" : [round(f, prec) for vr in ex_vrs for f in vr.pos]}

# Determine length of the alternating list for the A2 entry
mylength = int(len(dict["A1"])/3*2)

# Determine the two strings
string1 = "A"
string2 = "B"

# Use mod operator to determine (un)even numbers for the alternating list
dict["A2"] = [(string1 if i % 2 == 0 else string2) for i in range(mylength + 1)]

【讨论】：

谢谢，如果我必须在两个字符串而不是 0 和 1 之间交替，你会怎么做？

【解决方案2】：

假设你的 A2 长度是 10，那么你可以这样做：

len = 10 # Length of A2
rest = [i%2 for i in range(len) ]
print (rest)

# In case you want some other series of characters like ["a", "b", "a", "b" "a", "b" "a", "b" "a", "b" ]
# then you can use if else condition
rest = ["a" if i%2 == 0 else "b" for i in range(10) ]
print (rest)

【讨论】：