CODEWITHSUNDEEP
pythonindexing
Kim Delaney
Kim Delaney

Reputation: 37

Find index of strings within a list that contain a specific character

I am very new to Python, but I have a problem that Google hasn't yet solved for me. I have a list of strings (f_list). I would like to generate a list of the indicies of the strings that contain a specific character ('>').

Example: f_list = ['>EntryA', EntryB, '>EntryC', EntryD]

I would like to generate: index_list = [0, 2]

This code works, but I have to enter the exact name of a string (ie. >EntryA) for Value. If I enter '>' (as indicated below in the code example), it returns no values in index_list.

    f_list = ['>EntryA', 'EntryB', '>EntryC', 'EntryD']
    index_list = []

    def all_indices(v, qlist):
        idx = -1
        while True:
            try:
                idx = qlist.find(v, idx+1)
                index_list.append(idx)
            except ValueError:
                break
        return index_list

    all_indices('>', f_list)
    print(index_list)

Upvotes: 1

Views: 3382

Answers (3)

TerryA
TerryA

Reputation: 60024

If you are ever working with indexes, enumerate() is your function:

>>> f_list = ['>EntryA', 'EntryB', '>EntryC', 'EntryD']
>>> for i, j in enumerate(f_list):
...     if '>' in j:
...         print i
... 
0
2

In a function:

>>> def all_indices(v, qlist):
...     return [i for i, j in enumerate(f_list) if '>' in j]
...
>>> all_indices('>', f_list)
[0, 2]

Upvotes: 0

dawg
dawg

Reputation: 104092

You can use filter to find the strings:

>>> f_list = ['>EntryA', 'EntryB', '>EntryC', 'EntryD']
>>> filter(lambda s: '>' in s, f_list)
['>EntryA', '>EntryC']

Or use a list comprehension to find the indices:

>>> [i for i, s in enumerate(f_list) if '>' in s]
[0, 2]

Or you can find both with either:

>>> filter(lambda s: '>' in s[1], enumerate(f_list))
[(0, '>EntryA'), (2, '>EntryC')]

>>> [(i, s) for i, s in enumerate(f_list) if '>' in s]
[(0, '>EntryA'), (2, '>EntryC')]

Upvotes: 2

dansalmo
dansalmo

Reputation: 11694

>>> [i for i, s in enumerate(f_list) if '>' in s]
[0, 2]

Upvotes: 3

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