python - 以指定格式填充缺失值——Python

Question

我遇到一个明确要求我不要使用 numpy 或 pandas 的问题。

问题:

给定一个包含数字和 '_'(缺失值)符号的字符串，您必须按照说明替换 '_' 符号

Ex 1: _, _, _, 24 ==> 24/4, 24/4, 24/4, 24/4 i.e we. have distributed the 24 equally to all 4 places 

Ex 2: 40, _, _, _, 60 ==> (60+40)/5,(60+40)/5,(60+40)/5,(60+40)/5,(60+40)/5 ==> 20, 20, 20, 20, 20 i.e. the sum of (60+40) is distributed qually to all 5 places

Ex 3: 80, _, _, _, _  ==> 80/5,80/5,80/5,80/5,80/5 ==> 16, 16, 16, 16, 16 i.e. the 80 is distributed qually to all 5 missing values that are right to it

Ex 4: _, _, 30, _, _, _, 50, _, _  
==> we will fill the missing values from left to right 
    a. first we will distribute the 30 to left two missing values (10, 10, 10, _, _, _, 50, _, _)
    b. now distribute the sum (10+50) missing values in between (10, 10, 12, 12, 12, 12, 12, _, _) 
    c. now we will distribute 12 to right side missing values (10, 10, 12, 12, 12, 12, 4, 4, 4)

对于以逗号分隔值的给定字符串，它将包含两个缺失值数字，例如 ex: "_, _, x, _, _, "您需要填充缺失值 问:您的程序读取一个字符串像 ex: ", _, x, _, _, _"并返回填充序列 Ex:

Input1: "_,_,_,24"
Output1: 6,6,6,6

Input2: "40,_,_,_,60"
Output2: 20,20,20,20,20

Input3: "80,_,_,_,_"
Output3: 16,16,16,16,16

Input4: "_,_,30,_,_,_,50,_,_"
Output4: 10,10,12,12,12,12,4,4,4

我正在尝试使用拆分函数拆分列表中的字符串。然后我试图检查左边的空白并计算这些空白的数量然后一旦我遇到一个非空白，我将该数字除以总计数即(数字和之前遇到的空白)数字本身)并传播值并替换空白留下数字

然后我检查两个数字之间的空格，然后应用相同的逻辑，然后对右边的空格执行相同的操作。

但是，我在下面分享的代码会抛出各种错误，我相信我在上面分享的逻辑上存在漏洞，因此希望能提供解决此问题的见解

def blanks(S):

  a= S.split()
  count = 0
  middle_store = 0
  #left
  for i in range(len(a)):
    if(a[i]=='_'):
      count = count+1  #find number of blanks to the left of a number
    else:
      for j in range(0,i+1):
        #if there are n blanks to the left of the number speard the number equal over n+1 spaces
        a[j] = str((int(a[i])/(count+1)))
        middle_store= i
    break  

  #blanks in the middle
  denominator =0
  flag = 0
  for k in len(middle_store+1,len(a)):
    if(a[k] !='_'):
      denominator = (k+1-middle_store)
      flag=k
    break

  for p in len(middle_store,flag+1):
    a[p] = str((int(a[p])/denominator))

  #blanks at the right 
  for q in len(flag,len(a)):
    a[q] = str((int(a[q])/(len(a)-flag+1)))

S=  "_,_,30,_,_,_,50,_,_"
print(blanks(S))

Answer 1

模块化解决方案

# takes an array x and two indices a,b. 
# Replaces all the _'s with (x[a]+x[b])/(b-a+1)
def fun(x, a, b):
    if a == -1:
        v = float(x[b])/(b+1)
        for i in range(a+1,b+1):
            x[i] = v
    elif b == -1:
        v = float(x[a])/(len(x)-a)
        for i in range(a, len(x)):
            x[i] = v
    else:
        v = (float(x[a])+float(x[b]))/(b-a+1)
        for i in range(a,b+1):
            x[i] = v
    return x

def replace(text):
    # Create array from the string
    x = text.replace(" ","").split(",")
    # Get all the pairs of indices having number
    y = [i for i, v in enumerate(x) if v != '_']
    # Starting with _ ?
    if y[0] != 0:
        y = [-1] + y
    # Ending with _ ?
    if y[-1] != len(x)-1:
        y = y + [-1]    
    # run over all the pairs
    for (a, b) in zip(y[:-1], y[1:]): 
        fun(x,a,b)          
    return x

# Test cases
tests = [
    "_,_,_,24",
    "40,_,_,_,60",
    "80,_,_,_,_",
     "_,_,30,_,_,_,50,_,_"]

for i in tests:
    print (replace(i))