【python】| 阅读内置源码学习字符串常用方法

1. isdigit()

1-1. 对指定目录下文件名为数字的文件名进行排序并输出；

def iterkeys(self):
"""Return an iterator over keys."""
return iter(sorted(int(entry) for entry in os.listdir(self._path)
if entry.isdigit()))

1-2. 转换字符串格式时间为元组格式

def parsedate_tz(data):
"""Convert a date string to a time tuple.

Accounts for military timezones.
"""
if not data:
return None
# 2018-10-27 11:10:23
# Thu Mar  1 11:26:18 CST 2018
# _daynames = ['mon', 'tue', 'wed', 'thu', 'fri', 'sat', 'sun']

data = data.split()
if data[0][-1] in (',', '.') or data[0].lower() in _daynames:
# There's a dayname here. Skip it
del data[0]
else:
# no space after the "weekday,"?
i = data[0].rfind(',')
if i >= 0:
data[0] = data[0][i+1:]
if len(data) == 3: # RFC 850 date, deprecated
stuff = data[0].split('-')
if len(stuff) == 3:
data = stuff + data[1:]
if len(data) == 4:
s = data[3]
i = s.find('+')

if i > 0:
data[3:] = [s[:i], s[i+1:]]
else:
data.append('') # Dummy tz
if len(data) < 5:
return None
data = data[:5]
[dd, mm, yy, tm, tz] = data
mm = mm.lower()
if not mm in _monthnames:
dd, mm = mm, dd.lower()
if not mm in _monthnames:
return None
mm = _monthnames.index(mm)+1
if mm > 12: mm = mm - 12
if dd[-1] == ',':
dd = dd[:-1]
i = yy.find(':')
if i > 0:
yy, tm = tm, yy
if yy[-1] == ',':
yy = yy[:-1]
if not yy[0].isdigit():
yy, tz = tz, yy
if tm[-1] == ',':
tm = tm[:-1]
tm = tm.split(':')
if len(tm) == 2:
[thh, tmm] = tm
tss = '0'
elif len(tm) == 3:
[thh, tmm, tss] = tm
else:
return None
try:
yy = int(yy)
dd = int(dd)
thh = int(thh)
tmm = int(tmm)
tss = int(tss)
except ValueError:
return None
tzoffset = None
tz = tz.upper()
if tz in _timezones:
tzoffset = _timezones[tz]
else:
try:
tzoffset = int(tz)
except ValueError:
pass
# Convert a timezone offset into seconds ; -0500 -> -18000
if tzoffset:
if tzoffset < 0:
tzsign = -1
tzoffset = -tzoffset
tzsign = -1
tzoffset = -tzoffset
else:
tzsign = 1
tzoffset = tzsign * ( (tzoffset//100)*3600 + (tzoffset % 100)*60)
return (yy, mm, dd, thh, tmm, tss, 0, 1, 0, tzoffset)

def parsedate(data):
"""Convert a time string to a time tuple."""
t = parsedate_tz(data)
if t is None:
return t
return t[:9]

3. split

line.split(':')[-1].strip().lower()

if int(os.uname()[2].split('.')[0]) >= 9: pass

for line in pipe:  words = line.lower().split()