Pandas的ValueError数组长度必须相同

Question

遍历.mp3链接的大列表以获取元数据标记并将其保存到Excel文件中。导致此错误。谢谢你的帮助。谢谢。

    #print is_connected();
    # Create a Pandas dataframe from the data.
df = pd.DataFrame({'Links' : lines ,'Titles' : titles , 'Singers': finalsingers , 'Albums':finalalbums , 'Years' : years})

    # Create a Pandas Excel writer using XlsxWriter as the engine.
writer = pd.ExcelWriter(xlspath, engine='xlsxwriter')
    # Convert the dataframe to an XlsxWriter Excel object.
df.to_excel(writer, sheet_name='Sheet1')
    #df.to_excel(writer, sheet_name='Sheet1')

    # Close the Pandas Excel writer and output the Excel file.
writer.save()
Traceback (most recent call last):
  File "mp.py", line 87, in <module>
    df = pd.DataFrame({'Links' : lines ,'Titles' : titles , 'Singers': finalsingers , 'Albums':finalalbums , 'Years' : years})
  File "C:Python27libsite-packagespandascoreframe.py", line 266, in __init__
    mgr = self._init_dict(data, index, columns, dtype=dtype)
  File "C:Python27libsite-packagespandascoreframe.py", line 402, in _init_dict
    return _arrays_to_mgr(arrays, data_names, index, columns, dtype=dtype)
  File "C:Python27libsite-packagespandascoreframe.py", line 5409, in _arrays_to_mgr
    index = extract_index(arrays)
  File "C:Python27libsite-packagespandascoreframe.py", line 5457, in extract_index
    raise ValueError('arrays must all be same length')
ValueError: arrays must all be same length

Answer 1

你可以这样做来避免这个错误

a = {'Links' : lines ,'Titles' : titles , 'Singers': finalsingers , 'Albums':finalalbums , 'Years' : years}
df = pd.DataFrame.from_dict(a, orient='index')
df = df.transpose()

解释:

这会创建DataFrame，因为每个键(例如'Links')是一行，像这样，缺失的值实际上是缺失的列，这对pandas来说没有问题(在创建过程中，只有缺失的行导致ValueError)。之后，您将DataFrame转置(翻转轴)并使行变为列，从而产生您最初想要的DataFrame。

Answer 2

它告诉你数组(行，标题，finalsingers等…)的长度不相同。可以通过

进行测试

print(len(lines), len(titles), len(finalsingers)) # Print all of them out here

这将向您显示哪些数据是错误的，然后您需要做一些调查，找出正确的方法来纠正这一点。

Answer 3

可以用空元素填充最短列表:

def pad_dict_list(dict_list, padel):
    lmax = 0
    for lname in dict_list.keys():
        lmax = max(lmax, len(dict_list[lname]))
    for lname in dict_list.keys():
        ll = len(dict_list[lname])
        if  ll < lmax:
            dict_list[lname] += [padel] * (lmax - ll)
    return dict_list

dict_list = {'Links': [1, 2, 3], 'Titles': [1, 2, 3, 4], 'Singers': [1, 2], 'Albums': [1, 2, 3], 'Years': [1, 2, 3, 4]}
dict_list = pad_dict_list(dict_list, 0)
print(dict_list)

输出

{'Links': [1, 2, 3, 0], 'Titles': [1, 2, 3, 4], 'Singers': [1, 2, 0, 0], 'Albums': [1, 2, 3, 0], 'Years': [1, 2, 3, 4]}

Answer 4

重复的变量名导致了这个问题

Answer 5

我在读取JSON文件到pandas框架时遇到了同样的错误。添加linesbool，默认False参数解决了这个问题。

StringData = StringIO(obj.get()['Body'].read().decode('utf-8'))
                mydata = pdf.read_json(StringData, lines=True)