pandas update only true values with another dataframe-CodePudding

I have the following two tables:

df1 = pd.DataFrame(data={'val1': [True, False, False, True], 
                         'val2': [False, True, False, True], 
                         'val3': [True, True, False, True]},
                   index=pd.Series([1, 2, 3, 4], name='index'))

index	val1	val2	val3
1	True	False	True
2	False	True	True
3	False	False	False
4	True	True	True

df2 = pd.DataFrame(data={'val1': [1, 3, 3, 0], 
                         'val2': [5, 2, 2, 4], 
                         'val3': [5, 5, 3, 0]},
                   index=pd.Series([1, 2, 3, 4], name='index'))

index	val1	val2	val3
1	1	5	5
2	3	2	5
3	3	2	3
4	0	4	0

How do I only update the values in df1 that are True to get the following?

index	val1	val2	val3
1	1	False	5
2	False	2	5
3	False	False	False
4	0	4	0

I have tried df1.update(df2), but it override the False values in df1 as well.

CodePudding user response：

Use where to replace values in df2.

# replace values
df2.where(df1, False).reset_index()

CodePudding user response：

df1.replace(True, pd.NA, inplace=True)
df1.update(df2, overwrite=False)

Output:

        val1   val2   val3
index                     
1          1  False      5
2      False      2      5
3      False  False  False
4          0      4      0