如何在特定子字符串后获取字符串。
例如，我想在"world"
my_string="hello python world , i'm a beginner "之后获取字符串
答案 0 :(得分：294)
最简单的方法可能只是拆分你的目标词
my_string="hello python world , i'm a beginner "
print my_string.split("world",1)[1]
split将单词（或字符）拆分，并可选择限制拆分数。
在此示例中，拆分“世界”并将其限制为仅一次拆分。
答案 1 :(得分：48)
s1 = "hello python world , i'm a beginner "
s2 = "world"
print s1[s1.index(s2) + len(s2):]
如果您要处理s2中s1 不的情况，请使用s1.find(s2)而不是index。如果该通话的返回值为-1，那么s2不在s1。
答案 2 :(得分：37)
我很惊讶没有人提到partition。
def substring_after(s, delim):
return s.partition(delim)[2]
答案 3 :(得分：16)
答案 4 :(得分：3)
这是一个古老的问题，但我遇到了一个非常相同的情况，我需要将一个字符串拆分为使用“＆＃34; low＆＃34;对我来说问题是我在同一个字符串中有下面和下面的单词。
我用这种方式使用re模块解决了它
import re
string = '...below...as higher prices mean lower demand to be expected. Generally, a high reading is seen as negative (or bearish), while a low reading is seen as positive (or bullish) for the Korean Won.'
使用带有正则表达式的re.split来匹配确切的单词
stringafterword = re.split('\\blow\\b',string)[-1]
print(stringafterword)
' reading is seen as positive (or bullish) for the Korean Won.'
通用代码是：
re.split('\\bTHE_WORD_YOU_WANT\\b',string)[-1]
希望这可以帮助别人！
答案 5 :(得分：3)
您可以使用称为“子字符串”的程序包。只需输入“ pip install substring”。您只需提及开始和结束字符/索引即可获得子字符串。
例如：
import substring
s = substring.substringByChar("abcdefghijklmnop", startChar="d", endChar="n")
print(s)
输出：
答案 6 :(得分：3)
尝试这种通用方法：
import re
my_string="hello python world , i'm a beginner "
p = re.compile("world(.*)")
print (p.findall(my_string))
#[" , i'm a beginner "]
答案 7 :(得分：3)
在Python 3.9中，添加了一个新的removeprefix方法：
>>> 'TestHook'.removeprefix('Test')
'Hook'
>>> 'BaseTestCase'.removeprefix('Test')
'BaseTestCase'
答案 8 :(得分：1)
您要使用str.partition()：
>>> my_string.partition("world")[2]
" , i'm a beginner "
因为此选项比其他选项快 。
请注意，如果缺少分隔符，则会生成一个空字符串：
>>> my_string.partition("Monty")[2] # delimiter missing
''
如果要使用原始字符串，请测试从str.partition()返回的 second 值是否非空：
prefix, success, result = my_string.partition(delimiter)
if not success: result = prefix
您也可以使用str.split()，其限制为1：
>>> my_string.split("world", 1)[-1]
" , i'm a beginner "
>>> my_string.split("Monty", 1)[-1] # delimiter missing
"hello python world , i'm a beginner "
但是，此选项慢。在最佳情况下，与str.partition()相比，str.split()的访问速度容易快15％：
missing first lower upper last
str.partition(...)[2]: [3.745 usec] [0.434 usec] [1.533 usec] <3.543 usec> [4.075 usec]
str.partition(...) and test: 3.793 usec 0.445 usec 1.597 usec 3.208 usec 4.170 usec
str.split(..., 1)[-1]: <3.817 usec> <0.518 usec> <1.632 usec> [3.191 usec] <4.173 usec>
% best vs worst: 1.9% 16.2% 6.1% 9.9% 2.3%
这将显示每次执行的时间 ，此处输入的定界符丢失（最坏情况），放在最前面（最佳情况）或位于下半部，上半部或最后一个位置。最快的时间标有[...]，而<...>标有最差的时间。
上表是针对以下所有三个选项的综合时间试用而产生的。我在具有2.9 GHz Intel Core i7和16 GB ram的2017年型号15“ Macbook Pro上的Python 3.7.4上运行了测试。
此脚本会生成带有或不带有随机选择的定界符的随机句子，如果存在，则在生成的句子中的不同位置，以重复的随机顺序运行测试（产生最合理的结果，说明在此期间发生了随机OS事件测试），然后打印结果表：
import random
from itertools import product
from operator import itemgetter
from pathlib import Path
from timeit import Timer
setup = "from __main__ import sentence as s, delimiter as d"
tests = {
"str.partition(...)[2]": "r = s.partition(d)[2]",
"str.partition(...) and test": (
"prefix, success, result = s.partition(d)\n"
"if not success: result = prefix"
),
"str.split(..., 1)[-1]": "r = s.split(d, 1)[-1]",
}
placement = "missing first lower upper last".split()
delimiter_count = 3
wordfile = Path("/usr/dict/words") # Linux
if not wordfile.exists():
# macos
wordfile = Path("/usr/share/dict/words")
words = [w.strip() for w in wordfile.open()]
def gen_sentence(delimiter, where="missing", l=1000):
"""Generate a random sentence of length l
The delimiter is incorporated according to the value of where:
"missing": no delimiter
"first": delimiter is the first word
"lower": delimiter is present in the first half
"upper": delimiter is present in the second half
"last": delimiter is the last word
"""
possible = [w for w in words if delimiter not in w]
sentence = random.choices(possible, k=l)
half = l // 2
if where == "first":
# best case, at the start
sentence[0] = delimiter
elif where == "lower":
# lower half
sentence[random.randrange(1, half)] = delimiter
elif where == "upper":
sentence[random.randrange(half, l)] = delimiter
elif where == "last":
sentence[-1] = delimiter
# else: worst case, no delimiter
return " ".join(sentence)
delimiters = random.choices(words, k=delimiter_count)
timings = {}
sentences = [
# where, delimiter, sentence
(w, d, gen_sentence(d, w)) for d, w in product(delimiters, placement)
]
test_mix = [
# label, test, where, delimiter sentence
(*t, *s) for t, s in product(tests.items(), sentences)
]
random.shuffle(test_mix)
for i, (label, test, where, delimiter, sentence) in enumerate(test_mix, 1):
print(f"\rRunning timed tests, {i:2d}/{len(test_mix)}", end="")
t = Timer(test, setup)
number, _ = t.autorange()
results = t.repeat(5, number)
# best time for this specific random sentence and placement
timings.setdefault(
label, {}
).setdefault(
where, []
).append(min(dt / number for dt in results))
print()
scales = [(1.0, 'sec'), (0.001, 'msec'), (1e-06, 'usec'), (1e-09, 'nsec')]
width = max(map(len, timings))
rows = []
bestrow = dict.fromkeys(placement, (float("inf"), None))
worstrow = dict.fromkeys(placement, (float("-inf"), None))
for row, label in enumerate(tests):
columns = []
worst = float("-inf")
for p in placement:
timing = min(timings[label][p])
if timing < bestrow[p][0]:
bestrow[p] = (timing, row)
if timing > worstrow[p][0]:
worstrow[p] = (timing, row)
worst = max(timing, worst)
columns.append(timing)
scale, unit = next((s, u) for s, u in scales if worst >= s)
rows.append(
[f"{label:>{width}}:", *(f" {c / scale:.3f} {unit} " for c in columns)]
)
colwidth = max(len(c) for r in rows for c in r[1:])
print(' ' * (width + 1), *(p.center(colwidth) for p in placement), sep=" ")
for r, row in enumerate(rows):
for c, p in enumerate(placement, 1):
if bestrow[p][1] == r:
row[c] = f"[{row[c][1:-1]}]"
elif worstrow[p][1] == r:
row[c] = f"<{row[c][1:-1]}>"
print(*row, sep=" ")
percentages = []
for p in placement:
best, worst = bestrow[p][0], worstrow[p][0]
ratio = ((worst - best) / worst)
percentages.append(f"{ratio:{colwidth - 1}.1%} ")
print("% best vs worst:".rjust(width + 1), *percentages, sep=" ")