如何使用startswith函数生成像diff工具中的输出？

Question

请帮我解决（我觉得有趣）算法问题。 我今天花了一整天时间（迷路）来解决这个问题。 这是我的代码：

rman_config = ('''CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
''')

rman_new_parameters = [('RETENTION POLICY', 'TO RECOVERY WINDOW OF 2 DAYS'),
                       ('CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE', 'DISK TO controlfile_%F'),
                       ('CONTROLFILE AUTOBACKUP', 'ON'),
                       ('DEVICE TYPE', 'DISK PARALLELISM 4 BACKUP TYPE TO BACKUPSET')]

tuple_to_search = tuple([i[0] for i in rman_new_parameters])

for line in rman_config.splitlines():
    if line.startswith(tuple_to_search, 10):
        print('-  ' + line)
        print('+  CONFIGURE ' + '[parameter] ' + '[new value]' + ';')
    else:
        print('   ' + line)

哪里：

• rman_config - 具有默认配置的变量
• rman_new_parameters - 以随机顺序覆盖默认值的新参数，其中：
  • 元组中的第一个元素是一个参数（即CONTROLFILE AUTOBACKUP ）
  • 元组中的第二个元素是一个新值（即ON ）

到目前为止我有这个输出：

-  CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
+  CONFIGURE [parameter] [new value];
   CONFIGURE BACKUP OPTIMIZATION OFF; # default
   CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
-  CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
+  CONFIGURE [parameter] [new value];
-  CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
+  CONFIGURE [parameter] [new value];
-  CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
+  CONFIGURE [parameter] [new value];
   CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default

但我想要这个（就像在Diff ）：

-  CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
+  CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 2 DAYS;
   CONFIGURE BACKUP OPTIMIZATION OFF; # default
   CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
-  CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
+  CONFIGURE CONTROLFILE AUTOBACKUP ON;
-  CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
+  CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO cf_%F;
-  CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
+  CONFIGURE DEVICE TYPE DISK PARALLELISM 4 BACKUP TYPE TO BACKUPSET;
   CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default 

startswith函数很棒，但它没有告诉我哪个元组被识别（只返回True或False）。 我上面代码的问题是如何映射以下行：

if line.startswith(tuple_to_search, 10):

如果它对rman_new_parameters列表是真的。

我还没有弄清楚如何解决它？ 我会非常感激任何帮助。

Answer 1

for line in rman_config.splitlines():
    for params in rman_new_parameters:
        if line.startswith(params[0], 10):
            print('-  {}'.format(line))
            print('+  CONFIGURE {} {}'.format(*params))
            break
    else:
        print('   {}'.format(line))

基本上，我没有将元组传递给.startswith ，只是在一个循环中逐个测试。

另外， for + else 。

Answer 2

我不知道你要做什么。 但无论如何我写代码。 看看这个答案是否符合您的问题。 主要区别在于你的if-else块变为try-except块。 并且重点是index函数，它返回tuple_to_search第一次出现参数的tuple_to_search 。 我假设rman_new_parameters所有参数值都是从rman_config更改的。

rman_config = ('''CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
''')

rman_new_parameters = [('RETENTION POLICY', 'TO RECOVERY WINDOW OF 2 DAYS'),
                       ('CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE', 'DISK TO controlfile_%F'),
                       ('CONTROLFILE AUTOBACKUP', 'ON'),
                       ('DEVICE TYPE', 'DISK PARALLELISM 4 BACKUP TYPE TO BACKUPSET')]

tuple_to_search = [i[0] for i in rman_new_parameters]

for line in rman_config.splitlines():
    try:
        index = [line.startswith(tup, 10) for tup in tuple_to_search].index(True)
        print('-  ' + line)
        print('+  CONFIGURE ' + " ".join(rman_new_parameters[index]) + ';')
        #Add these if you don't need to check parameter once matched.
        #del rman_new_parameters[index]
        #del tuple_to_search[index]
    except:
        print('   ' + line)

输出：

-  CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
+  CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 2 DAYS;
   CONFIGURE BACKUP OPTIMIZATION OFF; # default
   CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
-  CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
+  CONFIGURE CONTROLFILE AUTOBACKUP ON;
-  CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
+  CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO controlfile_%F;
-  CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
+  CONFIGURE DEVICE TYPE DISK PARALLELISM 4 BACKUP TYPE TO BACKUPSET;
   CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default

PS

我的输出与您想要的输出略有不同（2行不同）。 我不知道为什么。 所以请确保它是您想要的输出。

你：

...
+  CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO cf_%F;
...
   CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default 

矿：

...
+  CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO controlfile_%F;
...
   CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
                                                                        ^
                                                                    no space here