如何计算某字符串中某事物发生的次数？

Question

In python, I remember there is a function to do this.

.count?

"The big brown fox is brown" brown = 2.

Answer 1

why not read the docs first, it's very simple:

>>> "The big brown fox is brown".count("brown")
2

Answer 2

One thing worth learning if you're a Python beginner is how to use interactive mode to help with this. The first thing to learn is the dir function which will tell you the attributes of an object.

>>> mystring = "The big brown fox is brown"
>>> dir(mystring)
['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__
ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__g
t__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__
', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '
__rmul__', '__setattr__', '__str__', 'capitalize', 'center', 'count', 'decode',
'encode', 'endswith', 'expandtabs', 'find', 'index', 'isalnum', 'isalpha', 'isdi
git', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lst
rip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit'
, 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', '
translate', 'upper', 'zfill']

Remember, in Python, methods are also attributes. So now he use the help function to inquire about one of the methods that looks promising:

>>> help(mystring.count)
Help on built-in function count:

count(...)
    S.count(sub[, start[, end]]) -> int

    Return the number of non-overlapping occurrences of substring sub in
    string S[start:end].  Optional arguments start and end are interpreted
    as in slice notation.

This displays the docstring of the method - some help text which you should get in to the habit of putting in your own methods too.