Conditional appending of data to a pandas dataframe

I am fairly new in Python. I have two pandas data frames ak12_01 and T01: Data sets

I want to add a given value from T01 to ak12_01 on two conditions:

1) if T01['coordID'] == ak12_01['coordID']

2) if T01(column name) == ak12_01['doy']. In the T01 dataset, the column names represent the doy (day of the year)

I get an error when comparing the 'coordID' from the two dataset as they are not equally long (Can only compare identically-labeled Series objects). Is there a smart way of adding the given value from T01 to ak_12_01 based on these to conditions?