Python 2.7使用列表運行函數的問題

Question

在Python 2.7中，我的函數pop(y,p)的代碼可以很好地工作，但函數aveChange(p,y)返回多條打印的線條，我只需要打印1行來說明每年人口變化的平均值。

，功能change(p,y,b)只是說：

NameError: name 'b' is not defined 

到目前爲止我的代碼如下：

def biggerThan(): 
    l=raw_input('Enter a list of numbers, separate each number with a comma:').split(',') 
    a=map(int,l) 
    n=int(raw_input('Enter another number:')) 
    a2=[i for i in a if i>n] 
    print a2 

    p = [151868, 153982, 156393, 158956, 161884, 165069, 168088, 
    171187, 174149, 177135, 179979, 182992, 185771, 188483, 
    191141, 193526, 195576, 197457, 199399, 201385, 203984, 
    206827, 209284, 211357, 213342, 215465, 217563, 219760, 
    222095, 224567, 227225, 229466, 231664, 233792, 235825, 
    237924, 240133, 242289, 244499, 246819, 249623] 
    y1=1950 
    y2=1991 
    y=range(y1,y2) 
def pop(y,p): 
    fmt='{:<8}{:<20}{}' 
    print(fmt.format('', 'Year', 'Population')) 
    for i, (year, pop) in enumerate(zip(y, p)): 
     print(fmt.format(i, year, pop)) 

def aveChange(p,y): 
    p = [151868, 153982, 156393, 158956, 161884, 165069, 168088, 
    171187, 174149, 177135, 179979, 182992, 185771, 188483, 
    191141, 193526, 195576, 197457, 199399, 201385, 203984, 
    206827, 209284, 211357, 213342, 215465, 217563, 219760, 
    222095, 224567, 227225, 229466, 231664, 233792, 235825, 
    237924, 240133, 242289, 244499, 246819, 249623] 
    y1=1950 
    y2=1991 
    y=range(y1,y2) 
    yearly_change = [] 
    change=0.0 
    total_change=0 
    average_change=0 
    for i in range(len(p)): 
     p[i] = float(p[i]) 
     #calculate the change in population size for each two years 
    for i in xrange(1,len(p)): 
     change = p[i] - p[i-1] 
     yearly_change.append(change) 
     total_change = float(sum(yearly_change)) 
     average_change = total_change/40 
     print "The average annual change in population during the time period is",average_change 

def change(p,y,b): 
    p = [151868, 153982, 156393, 158956, 161884, 165069, 168088, 
    171187, 174149, 177135, 179979, 182992, 185771, 188483, 
    191141, 193526, 195576, 197457, 199399, 201385, 203984, 
    206827, 209284, 211357, 213342, 215465, 217563, 219760, 
    222095, 224567, 227225, 229466, 231664, 233792, 235825, 
    237924, 240133, 242289, 244499, 246819, 249623] 
    y1=1950 
    y2=1991 
    y=range(y1,y2) 
    yearly_change = [] 
    newchange=0.0 
    greatest_increase=0 
    smallest_increase=0 
    greatest_year=0 
    smallest_year=0 
    BASE_YEAR=1950 
    for i in range(1,len(p)): 
     newchange = p[b] - p[b-1] 
     yearly_change.append(newchange) 

     if b==1: 
      greatest_increase = newchange 
      smallest_increase = newchange 
      greatest_year = 1 
      smallest_year = 1 
     else: 
      if newchange>greatest_increase: 
       greatest_increase = newchange 
       greatest_year = b 
      elif newchange<smallest_increase: 
       smallest_increase = newchange 
       smallest_year = b 
      print("The year with the greatest increase in population was", 
       BASE_YEAR+greatest_year) 
      print("The year with the smallest increase in population was", 
       BASE_YEAR+smallest_year) 

Answer 1

移動你print語句for循環之外爲aveChange(p,y)：

for i in xrange(1,len(p)): 
    change = p[i] - p[i-1] 
    yearly_change.append(change) 
    total_change = float(sum(yearly_change)) 
    average_change = total_change/40 
print "The average annual change in population during the time period is ",average_change 

爲change(p, y, b)函數，確保你用3個參數調用它，並且你的所有參數都被定義了！因爲你與b調用函數時收到錯誤，但b沒有前調用函數之外定義！嘗試將其稱爲：

change(p, y, 5)