字典或列表？

Question

我需要能夠存儲數據，一個是數字，一個是它出現的次數。我有一個for循環調用返回字典的方法：

for x in range(total_holidays): 
    t = trial() 
    y = y + "\n" + str(x+1) + "," + str(t["brown"]) + "," + str(t["rainbow"]) + "," + str(t["nothing"]) + "," + str(t["days"]) 
    total += t["days"] 
    #print total 
    if x%10000 == 0: 
     y0.append(y) 
     y = "" 

基本上我需要算多少次的T [「天」]發生，數量幾乎每一次變化。如果你想完整的代碼看這裏：

https://math.stackexchange.com/questions/193846/how-many-trials-would-you-expect-to-give-you-an-accurate-answer

所以，我會怎麼做，然後我需要後打印這一切。

y是csv文件的文本，總計用於計算平均值。

---

正如mgilson建議我應該使用這個？

from collections import Counter 

a = [] 
for x in range(total_holidays): 
    t = trial() 
    y = y + "\n" + str(x+1) + "," + str(t["brown"]) + "," + str(t["rainbow"]) + "," + str(t["nothing"]) + "," + str(t["days"]) 
    total += t["days"] 
    a.append(t['days']) 
    #print total 
    if x%10000 == 0: 
     y0.append(y) 
     y = "" 
z = Counter(a) 
print z 

我應該有這樣的事情嗎？

Answer 1

你想要什麼collections.Counter類型，dict亞型專門用於這樣的任務：

import collections 
days_occurred = collections.Counter() 

for ...: 
    t = trial() 
    days_occurred[t['days']] += 1 

# total is now sum(days_occurred.itervalues()) 

# you print the counts by iterating over the dict 

for days, count in days_occurred.iteritems(): 
    print "%d: %d" % (days, count) 

Answer 2

您不需要手動構建CSV文件。 Python已經有一個內置的模塊：

import csv 

writer = csv.writer(open('output.csv', 'wb')) 

# ... 

for x in range(total_holidays): 
    t = trial() 

    writer.writerow([x + 1, t['brown'], t['rainbow'], t['nothing'], t['days']]) 
    total += t['days'] 

除此之外，你的問題到底是什麼？