python - 如何比较两个不同数据帧的数据

Question

我正在尝试使用 Python 比较 2 个 pandas 数据帧的数据。我得到了 1 列，它们都是通用的，但它们的名称不同。第一个列的名称是“File”，第二个列的名称是“Código da transação”。不管怎样，我创建了这个函数来比较数据，但是我在这些行中遇到了错误......为什么会发生这种情况？

def checar_valor(a,b):
    for i in range(len(a)):
        if  b.isin([a['File'][i]]): #ERROR
            print("O valor %s está presente nos dois dataframes" % a['File'][i])
        else:
            print("O valor %s está presente apenas no dataframe %s" % (a['File'][i], "a"))

for q in range(len(b)):
    if a.isin([b['Código da transação'][q]]): #ERROR
        print("O valor %s está presente nos dois dataframes" % b['Código da transação'][q])
    else:
        print("O valor %s está presente apenas no dataframe %s" % (b['Código da transação'][q], "b"))


Traceback (most recent call last):
  File "C:/Users/nick/PycharmProjects/WebCrawler/Extranet/testezin.py", line 75, in <module>
    checar_valor(rs, ga)
  File "C:/Users/nick/PycharmProjects/WebCrawler/Extranet/testezin.py", line 64, in checar_valor
    if  b.isin([a['File'][i]]): #ERRO
  File "C:\Users\nick\PycharmProjects\WebCrawler\venv\lib\site-packages\pandas\core\generic.py", line 1576, in __nonzero__
    .format(self.__class__.__name__))
ValueError: The truth value of a DataFrame is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

Answer 1

使用pd.DataFrame.where您可以获得一个包含两个DataFrame中相同位置的值的DataFrame

df1.where(df1.values==df2.values)

Edit : following your comment, this should work :

A = pd.DataFrame([4,2,3], columns = ['Number'])
B = pd.DataFrame([2,5,6], columns = ['Number'])

a = set(A['Number'])
b = set(B['Number'])

my_set = set(a | b) #put every value in a set, so that you don't check each column twice

for i in my_set:
    if i in A['Number'].values:
        if i in B['Number'].values:
            print(str(i) + ' is in both DataFrames')
        else :
            print(str(i) + ' is in A but not in B')
    else: #if the value is not in A, it is obviously in B
        print(str(i) + ' is in B but not in A')

输出:

2 is in both DataFrames 
3 is in A but not in B 
4 is in A but not in B
5 is in B but not in A 
6 is in B but not in A