title: Append columns pandas : TypeError: assign() takes 1 positional argument but 2 were given
body: <p>I wanted to append new column to the <strong>"trainData"</strong>, we are having 712 rows for both the data frames
  When I try to append a new column <strong>"Age"</strong> with <strong>.assign</strong> method throws me below error</p>
  
  <p>What is the right way to append columns using dataFrames? </p>
  
  <pre><code>df = pd.read_csv("data/train.csv")
  #Dropping the columns  
  df = df.drop(['Ticket','Cabin'], axis=1)
  #Dropping the na columns
  df = df.dropna() 
  print("Age ====", df["Age"])
  titanic_dummies = pd.get_dummies(df, columns=['Pclass', 'Sex', 'Embarked'])
  
  trainData = titanic_dummies[ ["Pclass_1", "Pclass_2", "Pclass_3","Sex_female","Sex_male","Embarked_C","Embarked_Q","Embarked_S"]]
  print("My train data",trainData)
  trainData = trainData.assign(df["Age"])
  </code></pre>
  
  <p>Below is exception </p>
  
  <pre><code>  File "&lt;ipython-input-79-3f3ce0263545&gt;", line 1, in &lt;module&gt;
      runfile('C:/RafiWork/TASK/Personal/Data Science/Algorithmica/Day2/Titanic_Example/Test Neural Network/decisiontree.py', wdir='C:/RafiWork/TASK/Personal/Data Science/Algorithmica/Day2/Titanic_Example/Test Neural Network')
  
    File "C:\RafiWork\Softwares\MiniConda\envs\python35\lib\site-packages\spyder\utils\site\sitecustomize.py", line 688, in runfile
      execfile(filename, namespace)
  
    File "C:\RafiWork\Softwares\MiniConda\envs\python35\lib\site-packages\spyder\utils\site\sitecustomize.py", line 101, in execfile
      exec(compile(f.read(), filename, 'exec'), namespace)
  
    File "C:/RafiWork/TASK/Personal/Data Science/Algorithmica/Day2/Titanic_Example/Test Neural Network/decisiontree.py", line 30, in &lt;module&gt;
      trainData = trainData.assign(df["Age"])
  
  TypeError: assign() takes 1 positional argument but 2 were given
  </code></pre>