I have a Pandas dataframe which has a column of string data that consists of two distinct parts separated by forward slash. I want to extract text patterns from the 'right hand side' of the string but not if a particular string pattern is present. The following trivial example illustrates the issue.

```
import numpy as np
import pandas as pd
import re

myDF = pd.DataFrame({'pet':['rabbit','mammal/rabbit','mammal/small fluffy rabbit','mammal/lop-eared rabbit','mammal/many rabbits','mammal/jack rabbit']})

```

So, the dataframe looks like:

```
                          pet
0                      rabbit
1               mammal/rabbit
2  mammal/small fluffy rabbit
3     mammal/lop-eared rabbit
4         mammal/many rabbits
5          mammal/jack rabbit

```

I want to be able to extract rabbit-related terms but only if they occur to the right-hand side of a `/` separator and not if `rabbit` is preceded by `jack` (with or without an intervening space).

The regex I've come up with is:

```
rxStr = '(?P<bunny>(?<=/)(?<!jack)(?:.*rabbits?))'

```

...which I hoped would require any matches to be preceded by `/` but not if preceded by `jack`. However, it does not work as I had hoped. I've tried lots of variations without any luck.

```
rxStr = '(?P<bunny>(?<=/)(?<!jack)(?:.*rabbits?))'

rx = re.compile(rxStr,flags=re.I|re.X)

rabbitDF = myDF['pet'].str.extract(rx,expand=True)

myDF = myDF.join(rabbitDF)

print(myDF)

                          pet                bunny
0                      rabbit                  NaN
1               mammal/rabbit               rabbit
2  mammal/small fluffy rabbit  small fluffy rabbit
3     mammal/lop-eared rabbit     lop-eared rabbit
4         mammal/many rabbits         many rabbits
5          mammal/jack rabbit          jack rabbit

```

In row 0, the regex correctly fails to find a match because there is no `/` character. However, in row 5 `jack rabbit` is matched despite `jack` preceding `rabbit`.

How can I write a regular expression that would identify `rabbit` terms but only if preceded by `/` and not if preceded by `jack`? Any explanation of why the regex given above fails would also be very much appreciated.