PYTHON

combine 2 dataframes based on equal values in columns

import pandas as pd
pd.merge(df1, df2, on="Name")

#Only rows are kept for which common keys are found in both data frames. 
#In case you want to keep all rows from the left data frame and only add values from df2 
#where a matching key is available, you can use how="left":

pd.merge(df1, df2, on="Name", how="left")

pandas column name equal to another column value

In [2]: df
Out[2]:
    A  B
0  p1  1
1  p1  2
2  p3  3
3  p2  4

In [3]: df.loc[df['B'] == 3, 'A']
Out[3]:
2    p3
Name: A, dtype: object

In [4]: df.loc[df['B'] == 3, 'A'].iloc[0]
Out[4]: 'p3'

pandas set one column equal to another

In [300]:
df.loc[df['colA'] == 'a', 'colC'] = df['colB']
df['colC'] = df['colC'].fillna(0)
df

Out[300]:
   id colA  colB  colC
0   0    a    13    13
1   1    a    52    52
2   2    b    16     0
3   3    a    34    34
4   4    b   946     0