Pandas: Check if a substring exists in another column then create a new column with a specific value

Question

I this dataframe:

Receipt Description Card Member Account Cost
200a apple adam 08203928 $2
20022a pear bob 08203228 $7
202a orange alice 0820321228 $8

I want to check if a value in the description column contains a specific substring. For example the first row (adam) has the description of "apple". I want to check to see if the substring "appl" exists in this description column.

If so I then want to create a new column named Data which would then store the value need more apples . If no substring of "appl" is found I dont want to store anything in this column.

This is what the expected new dataframe would look like.

Receipt Description Card Member Account Cost **Data**
200a apple adam 08203928 $2 need more apples
20022a pear bob 08203228 $7
202a orange alice 0820321228 $8

Answer 1

You can try this:

Example 1:

df["**Data**"] = df["Description"].map(lambda x: "apple containes" if "appl" in x else '')

Example 2

If you have mapping of every fruit to check then you could create like this

desc = {"appl":"need more apples","pear": "need more pear"}

def check_desc(x):
    for key in desc:
        if key.lower() in x.lower():
            return desc[key]
    return ''

df["**Data**"] = df["Description"].map(lambda x: check_desc(x))

Answer 2

contains a string and np.where() to check if it contains a string. I do.

df['**Data**'] = np.where(df['Description'].str.contains('apple'),'need more apples','')