pandas中aggregation无法运行

Terence888

import numpy as np
import pandas as pd
from pandas import Series, DataFrame
!dir C:\Users\Thinkpad\coding-156-master\coding-156\homework
df = pd.read_csv(r'C:\Users\Thinkpad\coding-156-master\coding-156\homework\city_weather.csv')
g = df.groupby('city')
def foo(attr):
    return attr.max() - attr.min()
g.agg(foo)

出现如下报错：
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[106], line 1
----> 1 g.agg(foo)

File ~\anaconda3\Lib\site-packages\pandas\core\groupby\generic.py:1482, in DataFrameGroupBy.aggregate(self, func, engine, engine_kwargs, *args, **kwargs)
   1480 gba = GroupByApply(self, [func], args=(), kwargs={})
   1481 try:
-> 1482     result = gba.agg()
   1484 except ValueError as err:
   1485     if "No objects to concatenate" not in str(err):

File ~\anaconda3\Lib\site-packages\pandas\core\apply.py:193, in Apply.agg(self)
    190     return self.agg_dict_like()
    191 elif is_list_like(func):
    192     # we require a list, but not a 'str'
--> 193     return self.agg_list_like()
    195 if callable(func):
    196     f = com.get_cython_func(func)

File ~\anaconda3\Lib\site-packages\pandas\core\apply.py:326, in Apply.agg_list_like(self)
    318 def agg_list_like(self) -> DataFrame | Series:
    319     """
    320     Compute aggregation in the case of a list-like argument.
    321
   (...)
    324     Result of aggregation.
    325     """
--> 326     return self.agg_or_apply_list_like(op_name="agg")

File ~\anaconda3\Lib\site-packages\pandas\core\apply.py:1571, in GroupByApply.agg_or_apply_list_like(self, op_name)
   1566 # Only set as_index=True on groupby objects, not Window or Resample
   1567 # that inherit from this class.
   1568 with com.temp_setattr(
   1569     obj, "as_index", True, condition=hasattr(obj, "as_index")
   1570 ):
-> 1571     keys, results = self.compute_list_like(op_name, selected_obj, kwargs)
   1572 result = self.wrap_results_list_like(keys, results)
   1573 return result

File ~\anaconda3\Lib\site-packages\pandas\core\apply.py:385, in Apply.compute_list_like(self, op_name, selected_obj, kwargs)
    379 colg = obj._gotitem(col, ndim=1, subset=selected_obj.iloc[:, index])
    380 args = (
    381     [self.axis, *self.args]
    382     if include_axis(op_name, colg)
    383     else self.args
    384 )
--> 385 new_res = getattr(colg, op_name)(func, *args, **kwargs)
    386 results.append(new_res)
    387 indices.append(index)

File ~\anaconda3\Lib\site-packages\pandas\core\groupby\generic.py:257, in SeriesGroupBy.aggregate(self, func, engine, engine_kwargs, *args, **kwargs)
    255 kwargs["engine"] = engine
    256 kwargs["engine_kwargs"] = engine_kwargs
--> 257 ret = self._aggregate_multiple_funcs(func, *args, **kwargs)
    258 if relabeling:
    259     # columns is not narrowed by mypy from relabeling flag
    260     assert columns is not None  # for mypy

File ~\anaconda3\Lib\site-packages\pandas\core\groupby\generic.py:362, in SeriesGroupBy._aggregate_multiple_funcs(self, arg, *args, **kwargs)
    360     for idx, (name, func) in enumerate(arg):
    361         key = base.OutputKey(label=name, position=idx)
--> 362         results[key] = self.aggregate(func, *args, **kwargs)
    364 if any(isinstance(x, DataFrame) for x in results.values()):
    365     from pandas import concat

File ~\anaconda3\Lib\site-packages\pandas\core\groupby\generic.py:294, in SeriesGroupBy.aggregate(self, func, engine, engine_kwargs, *args, **kwargs)
    291     return self._python_agg_general(func, *args, **kwargs)
    293 try:
--> 294     return self._python_agg_general(func, *args, **kwargs)
    295 except KeyError:
    296     # KeyError raised in test_groupby.test_basic is bc the func does
    297     #  a dictionary lookup on group.name, but group name is not
    298     #  pinned in _python_agg_general, only in _aggregate_named
    299     result = self._aggregate_named(func, *args, **kwargs)

File ~\anaconda3\Lib\site-packages\pandas\core\groupby\generic.py:327, in SeriesGroupBy._python_agg_general(self, func, *args, **kwargs)
    324 f = lambda x: func(x, *args, **kwargs)
    326 obj = self._obj_with_exclusions
--> 327 result = self._grouper.agg_series(obj, f)
    328 res = obj._constructor(result, name=obj.name)
    329 return self._wrap_aggregated_output(res)

File ~\anaconda3\Lib\site-packages\pandas\core\groupby\ops.py:864, in BaseGrouper.agg_series(self, obj, func, preserve_dtype)
    857 if not isinstance(obj._values, np.ndarray):
    858     # we can preserve a little bit more aggressively with EA dtype
    859     #  because maybe_cast_pointwise_result will do a try/except
    860     #  with _from_sequence.  NB we are assuming here that _from_sequence
    861     #  is sufficiently strict that it casts appropriately.
    862     preserve_dtype = True
--> 864 result = self._aggregate_series_pure_python(obj, func)
    866 npvalues = lib.maybe_convert_objects(result, try_float=False)
    867 if preserve_dtype:

File ~\anaconda3\Lib\site-packages\pandas\core\groupby\ops.py:885, in BaseGrouper._aggregate_series_pure_python(self, obj, func)
    882 splitter = self._get_splitter(obj, axis=0)
    884 for i, group in enumerate(splitter):
--> 885     res = func(group)
    886     res = extract_result(res)
    888     if not initialized:
    889         # We only do this validation on the first iteration

File ~\anaconda3\Lib\site-packages\pandas\core\groupby\generic.py:324, in SeriesGroupBy._python_agg_general.<locals>.<lambda>(x)
    322     alias = com._builtin_table_alias[func]
    323     warn_alias_replacement(self, orig_func, alias)
--> 324 f = lambda x: func(x, *args, **kwargs)
    326 obj = self._obj_with_exclusions
    327 result = self._grouper.agg_series(obj, f)

Cell In[105], line 2, in foo(attr)
      1 def foo(attr):
----> 2     return attr.max() - attr.min()

TypeError: unsupported operand type(s) for -: 'str' and 'str'

wp231957

你那个感叹号 是什么东东  python 有这个语法吗

Terence888

wp231957 发表于 2024-7-27 15:01
你那个感叹号 是什么东东  python 有这个语法吗

jupyternotebook环境下查找指定文件夹内容的语法