熊猫索引和列创建

Question

I have a dataset, df .

I extracted another dataset from df , df_rec , based on a certain condition.

I can access the indexes of df_rec by df_rec.index.

Now, I want to create a column in df, where the index in df if matches with indexes in df_rec should be populated as 1 otherwise 0.

Any help, will be appreciated.

I am thinking, like, which throws error.

df['reccurences'] = 0
df['reccurences'][df.index in df_rec.index] = 1

Answer 1

You can use map on the index of df to chek whether it is in df_res and set the value accordingly as shown below.

df = pd.DataFrame()

df['X'] = [1, 2, 3, 4, 5, 6]
df['Y'] = [10, 20, 30, 40, 50, 60]

df_res = df.loc[df['X'] > 3]

df['C'] = df.index.map(lambda x : 1 if x in df_res.index else 0)

OR you can do like this

df['C'] = [1 if x in df_res.index else 0 for x in df.index]