Python ing list learning and python ing

Python ing list learning and python ing

List ing is a very useful method. By applying a function to each element in the list to convert data, you can use a policy or method to traverse and compute each element.

 

For example:

 

 

?

12345678910111213141516171819202122232425262728293031323334

params = {"server":"mpilgrim", \                "database":"master", \                "uid":"sa", \                "pwd":"secret" \                }print ["%s=%s" % (k, params[k]) for k in params.keys()]print ';'.join(["%s=%s" % (k, params[k]) for k in params.keys()])The returned result is:The returned result is:['uid=sa', 'pwd=secret', 'database=master', 'server=mpilgrim'] We can also improve the conversion of tuples into strings and use the join function method.'uid=sa;pwd=secret;database=master;server=mpilgrim'(The join function is used not only for tuples but also for lists. The function is string-based)In contrast to join, split converts a string to a metagroup.See the following applications.<pre name="code" class="python">>>> <span style="font-family: Arial, Helvetica, sans-serif;">str = 'server=mpilgrim;uid=sa;database=master;pwd=secret'</span></pre>>>> str.split(';')<br>['server=mpilgrim', 'uid=sa', 'database=master', 'pwd=secret']<br>>>> str.split(';', 1)<br>['server=mpilgrim', 'uid=sa;database=master;pwd=secret']<br>>>> str.split(';', 2)<br>['server=mpilgrim', 'uid=sa', 'database=master;pwd=secret']<pre class="brush:java;"></pre><p></p><p><br></p><P> <strong> List ing case: </strong> </p><pre class="brush:java;"><pre class="brush:java;">>>> li = [1, 9, 8, 4]>>> [elem*2 for elem in li] 1[2, 18, 16, 8]>>> li[1, 9, 8, 4]</pre><br><br></pre><br>