编程范式¶
- 文件操作 （
IO） - 字符串
open
open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)
'r' open for reading (default)
'w' open for writing, truncating the file first
'x' open for exclusive creation, failing if the file already exists
'a' open for writing, appending to the end of the file if it exists
'b' binary mode
't' text mode (default)
'+' open a disk file for updating (reading and writing)
'U' universal newlines mode (deprecated)In [10]:
# read()
f = open('data/sample.txt', 'rt')
dat = f.read()
f.close()
print(dat)
In [11]:
# read(chunksize)
f = open('data/sample.txt')
dat = f.read(100)
f.close()
print(dat)
In [12]:
# readline
f = open('data/sample.txt', 'rt')
while True:
line = f.readline()
if not line:
break
print(line)
f.close()
In [13]:
# readline
# 去掉行尾 '\n'
f = open('data/sample.txt', 'rt')
while True:
line = f.readline()
if not line:
break
print(line.rstrip())
f.close()
In [14]:
# 迭代器读取
f = open('data/sample.txt', 'rt')
for line in f:
print(line.rstrip())
f.close()
In [15]:
# readlines 读取所有行
f = open('data/sample.txt', 'rt')
lines = f.readlines()
for line in lines:
print(line.rstrip())
f.close()
写文件¶
write()
In [16]:
fo = open('data/test.txt', 'wt')
fo.write('something')
fo.close()
In [17]:
!cat data/test.txt
In [18]:
with open('data/sample.txt', 'rt') as fi:
for line in fi:
print(line.rstrip())
字符串¶
传统的 %¶
In [19]:
"The Value is %012.8f" % 23.253427
Out[19]:
In [20]:
"RA is %12.8f, Dec is %12.8f" % (332.202274, -2.056767)
Out[20]:
In [22]:
coord = {'RA': 332.202274, 'Dec': -2.056767}
"RA is %(RA)12.8f, Dec is %(Dec)12.8f" % coord
Out[22]:
.format¶
[[fill]align][sign][#][0][width][,][.precision][type]fill填充符, 除{和}以外的其他字符align对齐方式sign符号width宽度precision精度type转换类型
align 对齐方式
<左>右，默认=仅对数值类型有效^居中
sign 符号
+正数前加+，负数前加--正数前不加+，负数前加-，默认空格正数前加空格，负数前加-
type 转换类型
b二进制c字符d十进制，默认o9进制x16进制小写X16进制大写e默认精度是6E大写f浮点，默认精度6Fnan -> NAN， inf-> INFgG
In [23]:
"RA is {0:12.8f}, Dec is {1:12.8f}".format(332.202274, -2.056767)
Out[23]:
In [27]:
"RA is {RA:12.8f}, Dec is {Dec:12.8f}".format(RA=332.202274, Dec=-2.056767)
Out[27]:
In [28]:
coord = {'RA': 332.202274, 'Dec': -2.056767}
"RA is {0[RA]:12.8f}, Dec is {0[Dec]:12.8f}".format(coord)
Out[28]:
In [30]:
"RA is {}, Dec is {}".format(332.202274, -2.056767)
Out[30]:
In [41]:
# Sample
print("decimal hex char {0:^40}".format("name"))
print("------- ----- ------ {0}".format("-"*40))
for v in range(10018, 10028):
print("{0:7} {0:^5X} {0:^3c}".format(v))
print("------- ----- ------ {0}".format("-"*40))
In [ ]: