How to extract first 8 characters from a string in pandas

Question

I have column in a dataframe and i am trying to extract 8 digits from a string. How can I do it

    Input
 Shipment ID
20180504-S-20000
20180514-S-20537
201         


        

Answer 1

You can also decide to delete from -S to the end

df["Order_Date"]=df['Shipment ID'].replace(regex=r"\-.*",value="")
df
        Shipment ID Order_Date
0  20180504-S-20000   20180504
1  20180514-S-20537   20180514
2  20180514-S-20541   20180514
3  20180514-S-20644   20180514
4  20180514-S-20644   20180514
5  20180516-S-20009   20180516
6  20180516-S-20009   20180516
7  20180516-S-20009   20180516
8  20180516-S-20009   20180516

Also you can capture the first 8 digits then delete everything and replace back with a backreference of the captured group:

df['Shipment ID'].replace(regex=r"(\d{8}).*",value="\\1")