来自输入文件 csv 和列表的 itertools.combination

Question

我有一个 CSV 文件 (out.txt)，格式如下

red,green,blue
banana,apple,orange

我正在尝试生成所有两种组合，以便将输出放入 output.csv，如下所示

[red,green][red,blue][green,blue]
[banana,apple][banana,orange][apple,orange]

我的单行代码是

import csv

with open('out.txt', newline='') as csvfile:
    csvdata = list(csv.reader(csvfile))

print(csvdata)

r = 2; 
n = len(csvdata); 
print(n)

def printCombination(csvdata, n, r): 
    data = [0]*r; 
    print (data)

    combinationUtil(csvdata, data, 0,  
                    n - 1, 0, r); 

def combinationUtil(csvdata, data, start,  
                    end, index, r): 

    if (index == r): 
        for j in range(r): 
            print(data[j], end = " "); 
        print(); 
        return; 

    i = start;  
    while(i <= end and end - i + 1 >= r - index): 
        data[index] = csvdata[i]; 
        combinationUtil(csvdata, data, i + 1,  
                        end, index + 1, r); 
        i += 1; 

printCombination(csvdata, n, r); 

csvdata 打印为

[['red', 'green', 'blue'], ['banana', 'apple', 'orange']]

但是，如果我像这样手动定义一个数组

[1,2,3]

它返回正确的答案。我该如何处理列表？

我如何将输出写入 csv ？

Answer 1

你需要：

• 分别读取每一行
• 为每一行获取组合（我在下面使用itertools.combinations）
• 将该 itertools-generator 列表的 str 表示形式打印到输出文件的一行中（从中删除 '）
• 添加换行符
• 对所有行都这样做

要获得您的确切输出文件，我必须删除 ' 表示字符串：

with open ("data.txt","w") as f:
    f.write("red,green,blue\nbanana,apple,orange")

# store each line as list of words seperately    
lines = []
with open("data.txt") as f:
    for l in f:
        l = l.strip() # remove \n
        if l:
            lines.append( list(w.strip() for w in l.split(",")))

print(lines) # [['red', 'green', 'blue'], ['banana', 'apple', 'orange']]

from itertools import combinations

with open("result.txt", "w") as f:
    for l in lines:
        for c in combinations(l,2):
            f.write(str(list(c)).replace("'","")) # remove the ' of strings
        f.write("\n")

print(open("result.txt").read())

输出：

# what was read into `lines` from the file
[['red', 'green', 'blue'], ['banana', 'apple', 'orange']]

# output for 'result.txt' 
[red, green][red, blue][green, blue]
[banana, apple][banana, orange][apple, orange]