AttributeError: 'DataFrame' object has no attribute 'assign'-CodePudding

While assign a new column to my DataFrame I get this error here is my code

def check_header(header, df):
    print("Header : ",header)
    for item in header:
        if not item in df.columns:
            df = df.assign(item) #here I'm getting error
    return df[header]

I have check this post but din't work for me because my pandas version is satisfying it's

>>> import pandas as pd
>>> pd.__version__
'1.1.5'

what is problem in my code please help me.

CodePudding user response：

If need add new columns by header list with convert not matched values to new columns filled by NaNs use DataFrame.reindex:

df = pd.DataFrame(data = {"test":["mkt1","mkt2","mkt3"],
                         "test2":["cty1","cty2","cty3"]})


def check_header(header, df):
    return df.reindex(header, axis=1)

a = ['test','test1','test3']
print (check_header(a, df))
   test  test1  test3
0  mkt1    NaN    NaN
1  mkt2    NaN    NaN
2  mkt3    NaN    NaN

If need same values in new columns use fill_value parameter:

def check_header(header, df):
    return df.reindex(header, axis=1, fill_value=0)

a = ['test','test1','test3']
print (check_header(a, df))
   test  test1  test3
0  mkt1      0      0
1  mkt2      0      0
2  mkt3      0      0

If need different values per new column use DataFrame.assign with dictionary for new columns names like keys::

def check_header(header, df):
    diff = np.setdiff1d(header, df.columns)
    d = dict(zip(diff, diff))
    print (d)
    {'test1': 'test1', 'test3': 'test3'}
    
    return df.assign(**d).reindex(header, axis=1)

a = ['test','test1','test3']
print (check_header(a, df))
   test  test1  test3
0  mkt1  test1  test3
1  mkt2  test1  test3
2  mkt3  test1  test3