error: nothing to repeat at position 0 - Pandas

John D K -

Common Pandas error - error: nothing to repeat at position 0 can be result of several operations:

  • bad regular expression
  • reading CSV file with incorrect separator

Fix error: nothing to repeat at position 0

To fix error:

error: nothing to repeat at position 0

First we need to identify what is the reason for this error.
Once we know the reason the solutions might be:

  • change - .str.contains('?') to .str.contains('?', regex=False)
  • change the read_csv() sepators, encoding etc:
    • , sep='\t', engine='python', encoding='ISO-8859-1'

Data

Suppose we have data like the one below:

from faker import Faker
import pandas as pd

Faker.seed(0)
fake = Faker()
addr = []
for _ in range(5):
	addr.append(fake.address())
df = pd.DataFrame({'address':addr})
address
0 48764 Howard Forge Apt. 421\nVanessaside, VT 79393
1 PSC 4115, Box 7815\nAPO AA 41945
2 778 Brown Plaza\nNorth Jenniferfurt, VT 88077
3 3513 John Divide Suite 115\nRodriguezside, LA 93111
4 398 Wallace Ranch Suite 593\nIvanburgh, AZ 80818

Example - bad regex

If we try to search for a question mark we will end with Pandas error: error: nothing to repeat at position 0.

df['address'].str.contains('?')

The solution is either to escape the question mark or use regex=False:

df['address'].str.contains('\?')
df['address'].str.contains('?', regex=False)

Fix - read_csv

To fix the same error if we get it during reading CSV file by method read_csv file we can use parameters like:

pd.read_csv('data.csv', sep=''\*,\*'' , engine='python', encoding='ISO-8859-1')

Why do we get this error for read_csv? The reason is that some characters are special and treated in a different way. So we may need to escape them:

addition, separators longer than 1 character and different from '\s+' will be interpreted as regular expressions and will also force the use of the Python parsing engine. Note that regex delimiters are prone to ignoring quoted data. Regex example: '\r\t'.

Output

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