遍历两个熊猫数据帧，并将数据从一个数据帧附加到另一个

Question

I have two pandas data-frames that look like this:

data_frame_1:

index      un_id   city
1          abc     new york
2          def     atlanta
3          gei     toronto
4          lmn     tampa

data_frame_2:

index   name     un_id
1       frank    gei
2       john     lmn
3       lisa     abc
4       jessica  def

I need to match names to cities via the un_id column either in a new data-frame or an existing data-frame. I am having trouble figuring out how to iterate through one column, grab the un_id, iterate through the other un_id column in the other data-frame with that un_id, and then append the information needed back to the original data-frame.

Answer 1

use pandas merge :

In[14]:df2.merge(df1,on='un_id')
Out[14]: 
      name un_id      city
0    frank   gei   toronto
1     john   lmn     tampa
2     lisa   abc  new york
3  jessica   def   atlanta