KeyError - 不明白為什么

Question

嘗試獲取所有付款方式實例的計數：

    def paymentMethod(self):
        # Stores unique payment methods as dictionary keys with count of times used as values
        myDict = {}
        keyList = list(self.df['Institution'].unique())

        for i in keyList:
            count = self.df.groupby(i).count()
            myDict.update(i, count)

        print(myDict)

這是我的錯誤：

Traceback (most recent call last):
  File "final.py", line 40, in <module>
    x.paymentMethod()
  File "final.py", line 29, in paymentMethod
    count = self.df.groupby(i).count()
  File "C:\Users\Sean\AppData\Local\Programs\Python\Python38-32\lib\site-packages\pandas\core\frame.py", line 6515, in groupby
    return DataFrameGroupBy(
  File "C:\Users\Sean\AppData\Local\Programs\Python\Python38-32\lib\site-packages\pandas\core\groupby\groupby.py", line 525, in __init__
    grouper, exclusions, obj = get_grouper(
  File "C:\Users\Sean\AppData\Local\Programs\Python\Python38-32\lib\site-packages\pandas\core\groupby\grouper.py", line 786, in get_grouper
    raise KeyError(gpr)
KeyError: 'Chase Checking'

我真的不明白錯誤試圖告訴我什么？ 對不起，如果這是一個nooby問題。

Answer 1

groupby列名稱上的組。 您的 dataframe 沒有名為'Chase Checking'的列。

你似乎在尋找這個：

def paymentMethod(self):
    # Stores unique payment methods as dictionary keys with count of times used as values
    myDict = self.df['Institution'].value_counts().to_dict()

    print(myDict)

Answer 2

KeyError 用於列Chase Checking

您可以使用來自collections的Counter生成計數 map

from collections import Counter

def paymentMethod(self):
    count_map = Counter(self.df['Institution'])

    return count_map