pandas dataframe concat is giving unwanted NA/NaN columns
问题 Instead of this example where it is horizontal After Pandas Dataframe pd.concat I get NaNs, I'm trying vertical: import pandas a=[['Date', 'letters', 'numbers', 'mixed'], ['1/2/2014', 'a', '6', 'z1'], ['1/2/2014', 'a', '3', 'z1'], ['1/3/2014', 'c', '1', 'x3']] df = pandas.DataFrame.from_records(a[1:],columns=a[0]) f=[] for i in range(0,len(df)): f.append(df['Date'][i] + ' ' + df['letters'][i]) df['new']=f c=[x for x in range(0,5)] b=[] b += [['NA'] * (5 - len(b))] df_a = pandas.DataFrame.from