将列表字典写入CSV文件

Question

我在把一个包含列表的字典写入.csv文件时遇到了困难。

我的字典长这样：

dict[key1]=[1,2,3]
dict[key2]=[4,5,6]
dict[key3]=[7,8,9]

我希望生成的.csv文件看起来像这样：

key1  key2  key3
1     4     7  
2     5     8
3     6     9

首先，我写入表头：

outputfile = open (file.csv,'wb')
writefile = csv.writer (outputfile)
writefile.writerow(dict.keys())

到目前为止一切都很好……不过，我的问题是我不知道怎么把一个列表对应到正确的列上。例如：

for i in range(0,len(dict[key1])):
    writefile.writerow([dict[key1][i],dict[key2][i],dict[key3][i])

这样会随机填充列。另一个问题是，我必须手动填写键，不能用它来处理另一个有4个键的字典。

Answer 1

保存：

with open(path, 'a') as csv_file:
    writer = csv.writer(csv_file)
    for key, value in dict_.items():
        writer.writerow([key, ','.join(value)])
csv_file.close()        
print ('saving is complete') 

读取：

with open(csv_path, 'rb') as csv_file:
    reader = csv.reader(csv_file);
    temp_dict = dict(reader);
mydict={k:v.split(',') for k,v in temp_dict.items()}    
csv_file.close()
return mydict 

Answer 2

给定

dict = {}
dict['key1']=[1,2,3]
dict['key2']=[4,5,6]
dict['key3']=[7,8,9]

以下代码：

COL_WIDTH = 6
FMT = "%%-%ds" % COL_WIDTH

keys = sorted(dict.keys())

with open('out.csv', 'w') as csv:
    # Write keys    
    csv.write(''.join([FMT % k for k in keys]) + '\n')

    # Assume all values of dict are equal
    for i in range(len(dict[keys[0]])):
        csv.write(''.join([FMT % dict[k][i] for k in keys]) + '\n')

生成的csv文件看起来像：

key1  key2  key3
1     4     7
2     5     8
3     6     9

Answer 3

自己动手，不用csv模块：

d = {'key1' : [1,2,3],
     'key2' : [4,5,6],
     'key3' : [7,8,9]}

column_sequence = sorted(d.keys())
width = 6
fmt = '{{:<{}}}'.format(width)
fmt = fmt*len(column_sequence) + '\n'

output_rows = zip(*[d[key] for key in column_sequence])

with open('out.txt', 'wb') as f:
    f.write(fmt.format(*column_sequence))
    for row in output_rows:
        f.write(fmt.format(*row))

Answer 4

这个方法即使在关键字里的列表长度不一样时也能正常工作。

    with myFile:  
        writer = csv.DictWriter(myFile, fieldnames=list(clusterWordMap.keys()))   
        writer.writeheader()
        while True:
            data={}
            for key in clusterWordMap:
                try:
                    data[key] = clusterWordMap[key][ind]
                except:
                    pass
            if not data:
                break
            writer.writerow(data)

你可以使用pandas把它保存成csv格式：

df = pd.DataFrame({key: pd.Series(value) for key, value in dictmap.items()})
df.to_csv(filename, encoding='utf-8', index=False)

Answer 5

如果你不在乎列的顺序（因为字典是没有顺序的），你可以直接使用 zip()：

d = {"key1": [1,2,3], "key2": [4,5,6], "key3": [7,8,9]}
with open("test.csv", "wb") as outfile:
   writer = csv.writer(outfile)
   writer.writerow(d.keys())
   writer.writerows(zip(*d.values()))

结果：

key3    key2    key1
7       4       1
8       5       2
9       6       3

如果你在乎顺序，那你就需要先对键进行排序：

keys = sorted(d.keys())
with open("test.csv", "wb") as outfile:
   writer = csv.writer(outfile, delimiter = "\t")
   writer.writerow(keys)
   writer.writerows(zip(*[d[key] for key in keys]))

结果：

key1    key2    key3
1       4       7
2       5       8
3       6       9