检查字符串中的字符后面是否有空格

Question

我正在尝试编写一个函数，通过在单词之间使用空格来分解驼峰式大小写。如何检查char后面是否已经有空格?

def solution(s):
space = ' '
for chr in s:
if chr.isupper() == True:
new_str = s.replace(chr, space + chr)
return new_str

输入:

"camelCaseWord"      # a word in camelCasing

输出:

"camel Case Word"    # separated by spaces where word starts with capital leter

我的解只给出"camelCase Word"

Answer 1

您的解决方案不起作用，因为您总是使用基础s作为"源代码":

s = "someWordWithCases" 

将"W"替换为" W"并存储在new_str中…然后把结果扔掉，用" C"替换"C"——再次使用原来的s——"W"又回来了，在它们之前没有添加空间。

---

通过添加来创建字符串是浪费的。字符串是不可变的，所以在创建新字符串后旧的字符串会被丢弃。

解决方案是将每个大写字母分割成一个列表，然后用空格连接列表元素:

你的最小修改:

def solution(s):
r = []
for chr in s:
# if chr is capital and ( r is empty OR the last one is not a space)         
if chr.isupper() and (not r or  r[-1] != " "):            
# add space then the capital letter
r.append(" "+chr)
else:
# only add letter
r.append(chr)
return ''.join(r)

或者使用切片的版本:

def solution(s):
k = []
start = 0
for i,c in enumerate(s):
if c.isupper() and start != i:
k.append(s[start:i])
start = i
if c == " ":
k.append(s[start:i])
start = i+1
if i > start:
k.append(s[start:])

return ' '.join(k)

# some test cases are "more" then pure camelCaseSpelling
tests = ["startsLowerThenHasWords", "StartsCapitalThenHasWords", 
"   starts with spaces no capitals", "  Has some Capitals",
"has Capitals ABC and Others that areNotCapitals"]
maxL = max(len(t) for t in tests)
for t in tests:
print(f"{t:<{maxL}} ==> {solution(t)}")

,

startsLowerThenHasWords                         ==> starts Lower Then Has Words
StartsCapitalThenHasWords                       ==> Starts Capital Then Has Words
starts with spaces no capitals               ==>    starts with spaces no capitals
Has some Capitals                             ==>   Has some Capitals
has Capitals ABC and Others that areNotCapitals ==> has Capitals A B C and Others that are Not Capitals

Answer 2

这个怎么样?我使用enumerate来获取迭代的索引。

def solution(s):
space = ' '
space_positions = []
for index, chr in enumerate(s):
print(chr)
if chr != space and chr.isupper() == True:
if s[index - 1] != space:
space_positions.insert(0, index)
for index in space_positions:
s = s[:index] + " " + s[index:]
return s