Python 如何以固定宽度打印字符串？

我有这个代码（打印字符串中所有排列的出现）

我想打印字符串变量中的所有置换事件

由于排列的长度不同，我想固定宽度，并以漂亮的字体打印，而不是像这样：

value   a - num of occurrences =    1
value   ab - num of occurrences =    1
value   abc - num of occurrences =    1
value   b - num of occurrences =    1
value   bc - num of occurrences =    1
value   bcd - num of occurrences =    1
value   c - num of occurrences =    1
value   cd - num of occurrences =    1
value   d - num of occurrences =    1

如何使用

格式

执行此操作

我找到了这些帖子，但与字母数字字符串不太匹配：

---

编辑2013-12-11-这个答案非常古老。它仍然是有效的和正确的，但是人们应该更喜欢这个

您可以这样使用：

>>> print '%5s' % 'aa'
   aa
>>> print '%5s' % 'aaa'
  aaa
>>> print '%5s' % 'aaaa'
 aaaa
>>> print '%5s' % 'aaaaa'
aaaaa

基本上：

• %

  字符通知python它必须将某些内容替换为令牌

• s

  字符通知python标记将是字符串

• 5

  （或任何您想要的数字）通知python在字符串中填充最多5个字符的空格

在您的特定情况下，可能的实现如下所示：

>>> dict_ = {'a': 1, 'ab': 1, 'abc': 1}
>>> for item in dict_.items():
...     print 'value %3s - num of occurances = %d' % item # %d is the token of integers
... 
value   a - num of occurances = 1
value  ab - num of occurances = 1
value abc - num of occurances = 1

旁注：我只是想知道你是否意识到这个问题的存在。例如，您可以通过以下方式在一行中获得所有组合的列表：

>>> [''.join(perm) for i in range(1, len(s)) for perm in it.permutations(s, i)]
['a', 'b', 'c', 'd', 'ab', 'ac', 'ad', 'ba', 'bc', 'bd', 'ca', 'cb', 'cd', 'da', 'db', 'dc', 'abc', 'abd', 'acb', 'acd', 'adb', 'adc', 'bac', 'bad', 'bca', 'bcd', 'bda', 'bdc', 'cab', 'cad', 'cba', 'cbd', 'cda', 'cdb', 'dab', 'dac', 'dba', 'dbc', 'dca', 'dcb']

---

通过使用

组合

和

count（）

结合使用

str.format

我发现使用

str.format

更优雅：

>>> '{0: <5}'.format('s')
's    '
>>> '{0: <5}'.format('ss')
'ss   '
>>> '{0: <5}'.format('sss')
'sss  '
>>> '{0: <5}'.format('ssss')
'ssss '
>>> '{0: <5}'.format('sssss')
'sssss'

---

编辑1： 正如评论中提到的：{0:中的

0

最初是作为@0x90答案的编辑发布的，但由于偏离了帖子的初衷而被拒绝，并建议作为评论或答案发布，所以我在这里包括了这篇短文

除了@0x90的答案外，还可以通过使用宽度变量（根据@user2763554的注释），使语法更加灵活：

或者，对于最大的、潜在的非pythonical隐式紧性，甚至忽略所有数字：

width=10
'{: <{}}'.format('sss', width)

这也适用于字符串格式

>>> width=10
>>> string = 'sss'
>>> f'{string: <{width}}'
'sss       '

宽度=10 >>>字符串='sss'

---

>>>f'{string:

格式

无疑是最优雅的方式，但您不能将其与python的

日志记录

模块一起使用，因此下面介绍如何使用

%

格式：

formatter = logging.Formatter(
    fmt='%(asctime)s | %(name)-20s | %(levelname)-10s | %(message)s',
)

这里，

-

表示左对齐，

s

前面的数字表示固定宽度

一些示例输出：

2017-03-14 14:43:42,581 | this-app             | INFO       | running main
2017-03-14 14:43:42,581 | this-app.aux         | DEBUG      | 5 is an int!
2017-03-14 14:43:42,581 | this-app.aux         | INFO       | hello
2017-03-14 14:43:42,581 | this-app             | ERROR      | failed running main

---

更多信息请参见此处的文档：

>print（f“{'123'：当您希望在一个print语句中打印多个元素时，这将有助于保持固定长度

25s
格式化带有25个空格的字符串，默认情况下左对齐

5d
格式化一个保留5个空格的整数，默认情况下右对齐

members=[“Niroshan”、“Brayan”、“Kate”]
打印（“\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
打印（{:25s}{:32s}{:35s}）。格式（“姓名”、“国家”、“年龄”））
打印（“\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
打印（{:25s}{:30s}{:5d}）。格式（成员[0]，“斯利兰卡”，20））
印刷品（{:25s}{:30s}{:5d}）。格式（成员[1]，“澳大利亚”，25））
印刷品（{:25s}{:30s}{:5d}）。格式（成员[2]，“英格兰”，30））
打印（“\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu

这个会打印出来

__________________________________________________________________
Name                      Country                          Age
__________________________________________________________________
Niroshan                  Srilanka                          20
Brayan                    Australia                         25
Kate                      England                           30
__________________________________________________________________

我发现
ljust（）
和
rjust（）
以固定宽度或宽度打印字符串非常有用

一个例子

print('123.00'.rjust(9))
print('123456.89'.rjust(9))

# expected output  
   123.00
123456.89

对于您的案例，您可以使用
fstring
打印案例

for prefix in unique:
    if prefix != "":
        print(f"value  {prefix.ljust(3)} - num of occurrences = {string.count(str(prefix))}")

预期产量

value  a   - num of occurrences = 1
value  ab  - num of occurrences = 1
value  abc - num of occurrences = 1
value  b   - num of occurrences = 1
value  bc  - num of occurrences = 1
value  bcd - num of occurrences = 1
value  c   - num of occurrences = 1
value  cd  - num of occurrences = 1
value  d   - num of occurrences = 1

您可以将
3
更改为置换字符串的最大长度。
打印“%10s”“%”mystring“怎么办"

在任何解决方案中都不作为选项列出。您也许应该提到负数给出左对齐的填充输出；这对初学者来说很难直观。@tripleee的+1表示@tripleee，如果没有您的负数给出左对齐的注释，我的脑袋会被敲得更长…thx m8。这比我不明白为什么Python中有这样的推向卷积，有一种方法在空白空间中填充一个特定的字符吗？例如，如果我们需要打印“05”而不是“5”。下面是一些使用f字符串进行优雅的固定宽度打印的技巧。此外，0表示format参数的位置，因此您可以做另外两件事：

{我无法再编辑上一条注释，这是需要的。
{这里是描述这些格式字符串和附加选项的Python。为了快速参考，
{0:that5中的空格可以是变量替换
>>>打印宽度20>>>打印“{0:您也可以使用数字，只需按
宽度=10；”的顺序列出变量{0:但这不会将字符串缩短到20个字符以上。请使用
'%（name）20.20s'
将20设置为最小和最大字符串长度！我最喜欢这个答案！
>>> width=10
>>> string = 'sss'
>>> f'{string: <{width}}'
'sss       '

formatter = logging.Formatter(
    fmt='%(asctime)s | %(name)-20s | %(levelname)-10s | %(message)s',
)

2017-03-14 14:43:42,581 | this-app             | INFO       | running main
2017-03-14 14:43:42,581 | this-app.aux         | DEBUG      | 5 is an int!
2017-03-14 14:43:42,581 | this-app.aux         | INFO       | hello
2017-03-14 14:43:42,581 | this-app             | ERROR      | failed running main

>>> print(f"{'123':<4}56789")
123 56789

__________________________________________________________________
Name                      Country                          Age
__________________________________________________________________
Niroshan                  Srilanka                          20
Brayan                    Australia                         25
Kate                      England                           30
__________________________________________________________________

print('123.00'.rjust(9))
print('123456.89'.rjust(9))

# expected output  
   123.00
123456.89

for prefix in unique:
    if prefix != "":
        print(f"value  {prefix.ljust(3)} - num of occurrences = {string.count(str(prefix))}")

value  a   - num of occurrences = 1
value  ab  - num of occurrences = 1
value  abc - num of occurrences = 1
value  b   - num of occurrences = 1
value  bc  - num of occurrences = 1
value  bcd - num of occurrences = 1
value  c   - num of occurrences = 1
value  cd  - num of occurrences = 1
value  d   - num of occurrences = 1