How to extract first 8 characters from a string in pandas

Question

I have a column in a data frame and I am trying to extract 8 digits from a string. How to do it

    Input

 Shipment ID

20180504-S-20000

20180514-S-20537

20180514-S-20541

20180514-S-20644

20180514-S-20644

20180516-S-20009

20180516-S-20009

20180516-S-20009

20180516-S-20009

Output:

Order_Date

20180504

20180514

20180514

20180514

20180514

20180516

20180516

20180516

20180516

I tried the below code and it didn't work.

data['Order_Date'] = data['Shipment ID'][:8]

Answer 1

You need to index with str which is apply for each value of Series:

data['Order_Date'] = data['Shipment ID'].str[:8]

For better performance if no NaNs values:

data['Order_Date'] = [x[:8] for x in data['Shipment ID']]

print (data)

        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

You can filter column by position, first N values like:

print (data['Shipment ID'][:2])

0    20180504-S-20000

1    20180514-S-20537

Name: Shipment ID, dtype: object

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