如何在选择不同列的条件下用第二个 DataFrame 中的值替换 DataFrame 中的值？

Question

I have a two DataFrames. df1:

A    |    B    |    C
-----|---------|---------|
25zx | b(50gh) |         |
50tr | a(70lc) | c(50gh) |

df2:

  A  |  B
-----|-----
25zx |  T
50gh |  K
50tr |  K
70lc |  T

I want to replace values in df1. The row that I'm comparing is df2['A'], but the value that I want to put in to df1 is value from the row df['B'].

So the final table would look like:

df3:

A    |    B    |    C
-----|---------|---------|
  T  |   b(K)  |         |
  K  |   a(T)  |   c(K)  |

Answer 1

Cast df2 to dict and use replace :

print (df.replace(df2.set_index("A")["B"].to_dict(), regex=True))

   A     B     C
0  T  b(K)  None
1  K  a(T)  c(K)