pandas:列的长度必须与键的长度相同

Question

我正在尝试将多个列重新格式化为字符串（它们包含nan，因此我不能将它们作为整数读入）。所有的列都是float64，我想让它们不带小数。

数据如下：

{'crash_id': {0: 201226857.0,
  1: 201226857.0,
  2: 2012272611.0,
  3: 2012272611.0,
  4: 2012298998.0},
 'driver_action1': {0: 1.0, 1: 1.0, 2: 29.0, 3: 1.0, 4: 3.0},
 'driver_action2': {0: 99.0, 1: 99.0, 2: 1.0, 3: 99.0, 4: 99.0},
 'driver_action3': {0: 99.0, 1: 99.0, 2: 99.0, 3: 99.0, 4: 99.0},
 'driver_action4': {0: 99.0, 1: 99.0, 2: 99.0, 3: 99.0, 4: 99.0},
 'harmful_event1': {0: 14.0, 1: 14.0, 2: 14.0, 3: 14.0, 4: 14.0},
 'harmful_event2': {0: 99.0, 1: 99.0, 2: 99.0, 3: 99.0, 4: 99.0},
 'harmful_event3': {0: 99.0, 1: 99.0, 2: 99.0, 3: 99.0, 4: 99.0},
 'harmful_event4': {0: 99.0, 1: 99.0, 2: 99.0, 3: 99.0, 4: 99.0},
 'most_damaged_area': {0: 14.0, 1: 2.0, 2: 14.0, 3: 14.0, 4: 3.0},
 'most_harmful_event': {0: 14.0, 1: 14.0, 2: 14.0, 3: 14.0, 4: 14.0},
 'point_of_impact': {0: 15.0, 1: 1.0, 2: 14.0, 3: 14.0, 4: 1.0},
 'vehicle_id': {0: 20121.0, 1: 20122.0, 2: 20123.0, 3: 20124.0, 4: 20125.0},
 'vehicle_maneuver': {0: 3.0, 1: 1.0, 2: 4.0, 3: 1.0, 4: 1.0}}

当我尝试将这些列转换为字符串时，将发生以下情况：

>> df[['crash_id','vehicle_id','point_of_impact','most_damaged_area','most_harmful_event','vehicle_maneuver','harmful_event1','harmful_event2','harmful_event3','harmful_event4','driver_action1','driver_action2','driver_action3','driver_action4']] = df[['crash_id','vehicle_id','point_of_impact','most_damaged_area','most_harmful_event','vehicle_maneuver','harmful_event1','harmful_event2','harmful_event3','harmful_event4','driver_action1','driver_action2','driver_action3','driver_action4']].applymap(lambda x: '{:.0f}'.format(x))

File "C:\Users\<name>\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\core\frame.py", line 2376, in _setitem_array
        raise ValueError('Columns must be same length as key')

ValueError: Columns must be same length as key

我以前从没见过这个错误，觉得这很简单……我做错什么了？

Answer 1

你的代码和你提供的字典一起为我运行。尝试创建一个函数来分别处理NaN案例；我认为它们会引起您的问题。

基本的如下：

def formatter(x):
    if x == None:
        return None
    else:
        return '{:.0f}'.format(x)