Python匹配列表並返回找到的值

Question

我正在嘗試計算CSV文件中最常見的值，並在CSV文件中的每個項目旁邊添加匹配項的值。例如：

CSV文件：

* 8 Values in Column 1* 
    HelloWorld 
    HelloWorld 
    HelloSaturn 
    HelloMars 
    HelloPluto 
    HelloSaturn 
    HelloMoon 
    HelloMoon 

Python代碼來計算最常見的：

#Removed Code - Take each row in CSV and append to list# 
    #Create new list, count common occurrences out of 8 items 
    newList = [] 
    counter = collections.Counter(newList) 
    d = counter.most_common(8) 
    print d 

打印輸出（已計算出上述CSV中最常用的值例如有兩個「HelloWorld的） ：

[('HelloWorld', 2), ('HelloMars', 1), ('HelloSaturn', 2), ('HelloPluto', 1), ('HelloMoon', 2)] 

我現在試圖讓這些值附加/插入到我的CSV文件例如：

* 8 Values in Column 1* *Occurrence* 
    HelloWorld 2 
    HelloWorld 2 
    HelloSaturn 2 
    HelloMars 1 
    HelloPluto 1 
    HelloSaturn 2 
    HelloMoon 2 
    HelloMoon 2 

我該怎麼做？

Answer 1

import csv 

# I fake here the opening and extracting from a CSV file 
# to obtain a list of the words of the first column 
ss = """HelloWorld 
HelloWorld 
HelloSaturn 
HelloMars 
HelloPluto 
HelloSaturn 
HelloMoon 
HelloMoon""" 
column = ss.splitlines() 


# Now, the counting 
from collections import Counter 
c = Counter(column) 

# Seeing the counter we got 
print '\n'.join(c) 

# Putting the result in a CSV file 
with open('resu.csv','wb') as g: 
    gw = csv.writer(g) 
    gw.writerows([item,c[item]] for item in column) 

Answer 2

您需要使用csv.writer對象重寫CSV文件：使用csv.reader

使用計算的出現頻率

1. 閱讀CSV文件到內存中（如行或東西的清單）您現有的代碼
2. 迭代您在步驟1中讀取的每一行。使用csv.writer輸出行中的每列。在行，輸出相應的頻率結束時，您在步驟2計算

代碼會是這個樣子（完全未經測試）：

import csv 
list_of_rows = list() 
with open(filename) as fin: 
    reader = csv.reader(fin) 
    for row in reader: 
     list_of_rows.append(row) 

# calculate frequency of occurrence 
counter = ... 

with open(filename, "w") as fout: 
    writer = csv.writer(fout) 
    for row in counter.most_common(8):    
     # row is now (word, frequency) 
     writer.writerow(row)