Pandas/numpy: Is there a way to check a string and to assign a value of the same row to another data-CodePudding

I want to check if a given string is in a df and give the value of another column in this row into a different dataframe. I tried something like this:

df2['value']=np.where(df1['one'].str.contains(string),df1['two'],)

string = 'ef'

df1 :

| one | two |

| :--- | -----: |

| abc | hello |

| def | there |

In the end column ['value'] of Dataframe shall contain the string 'there'.

df2 :

| key | value |

| :--- | -----: |

| ef | there |

CodePudding user response：

sring = 'ef'

df1['value'] = np.where(df1['one'].str.contains(string), df1['two'], df1['one'])

df1

   one    two  value
1  abc  hello    abc
2  def  there  there

CodePudding user response：

You can achieve this by using pandas' mask method:

df2 = (
    df1.assign(
        value=lambda df: df["one"].mask(df["one"].str.contains(string), df["two"])
    )
    .rename(columns={"two": "key"})
    .drop("one", axis=1)
)

Output:

    key     value
0   hello   abc
1   there   there