Filter Elements in Python Series Starting and Ending with Specific String

Input − Assume, you have a Series,

0    apple
1    oranges
2    alpha
3    aroma
4    beta

Output − And, the result for elements start and endswith ‘a’.

2    alpha
3    aroma

Solution 1

• Define a Series.

• Create regular expression to check start and endswith ‘a’

r'^[a]$|^([a]).*\1$'

• Create an empty list and set for loop and set if condition inside to check the pattern. It is defined below,

for i in data:
   if(re.search(exp, i)):
      ls.append(i)

• Finally, check the series using isin().

Example

Let us see the following implementation to get a better understanding.

import pandas as pd
import re
l = ["apple","oranges","alpha","aroma","beta"]
data = pd.Series(l)
exp = r'^[a]$|^([a]).*\1$'
ls = []
for i in data:
   if(re.search(exp, i)):
      ls.append(i)
print(data[data.isin(ls)])

Output

2 alpha
3 aroma

Solution 2

Example

import pandas as pd
import re
l = ["apple","oranges","alpha","aroma","beta"]
data = pd.Series(l)
result = list(filter(lambda x:x.startswith('a') and x.endswith('a'),l))
print(data[data.isin(result)])

Output

2 alpha
3 aroma