python - How can I figure out a new row by current row divide its last row by dataframe?

Question

 price = 
  price
0 111
1 222
2 333
3 444

I want newprice =

  price
0 111
1 222/111
2 333/222
3 444/333

Answer 1

Use df.shift with df.fillna:

In [1046]: df['new_price'] = df.price.div(df.price.shift()).fillna(df.price)

In [1047]: df
Out[1047]: 
   price   new_price
0    111  111.000000
1    222    2.000000
2    333    1.500000
3    444    1.333333