Python之列表的增删改查
列表的查
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] print(a[1:4])</pre>结果:
<pre class="brush:php;toolbar:false">['tom', 'jack', 'james']</pre>注意:
列表的切片的下标以 0 为开始。即: 下标0 --> klvchen,下标1 --> tom,..... 下标5 --> lucy。
列表的切换顾头不顾尾,例如:a [1:4],则不会取到列表下标为4的元素
从左到右,取到最后:
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] print(a[1:])</pre>结果:
<pre class="brush:php;toolbar:false">['tom', 'jack', 'james', 'lily', 'lucy']</pre>从左到右,取到倒数第二个值:
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] print(a[1:-1])</pre>结果:
<pre class="brush:php;toolbar:false">['tom', 'jack', 'james', 'lily']</pre>从左到右,隔一个去取:
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] print(a[1::2])</pre>结果:
<pre class="brush:php;toolbar:false">['tom', 'james', 'lucy']</pre>从右到左,一个一个去取:
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] print(a[3::-1])</pre>结果:
<pre class="brush:php;toolbar:false">['james', 'jack', 'tom', 'klvchen']</pre>从右到左去取
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] print(a[-2:-4:-1])</pre>结果:
<pre class="brush:php;toolbar:false">['lily', 'james']</pre>列表的增
append 方法默认插到最后一个位置
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] a.append("mary") print(a)</pre>结果:
<pre class="brush:php;toolbar:false">['klvchen', 'tom', 'jack', 'james', 'lily', 'lucy', 'mary']</pre>insert 方法将数据插入到任意一个位置
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] a.insert(1,"mary") print(a)</pre>结果:
<pre class="brush:php;toolbar:false">['klvchen', 'mary', 'tom', 'jack', 'james', 'lily', 'lucy']</pre>extend 方法可在列表的末尾一次性追加另一个序列中的多个值
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack"] b = ["james", "lily", "lucy"] a.extend(b) print(a)</pre>结果:
<pre class="brush:php;toolbar:false">['klvchen', 'tom', 'jack', 'james', 'lily', 'lucy']</pre>相关推荐:《Python视频教程》
列表的改
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] a[1]="tom2" print(a)</pre>结果:
<pre class="brush:php;toolbar:false">['klvchen', 'tom2', 'jack', 'james', 'lily', 'lucy'] a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] a[1:3]=["tom2", "jack2"] print(a)</pre>结果:
<pre class="brush:php;toolbar:false">['klvchen', 'tom2', 'jack2', 'james', 'lily', 'lucy']</pre>列表的删
remove 方法
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] a.remove("tom") print(a)</pre>结果:
<pre class="brush:php;toolbar:false">['klvchen', 'jack', 'james', 'lily', 'lucy']</pre>pop 方法
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] b = a.pop(1) print(a) print(b)</pre>结果:
注意 pop 方法会返回删除的元素
del 方法
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] del a[1] print(a)</pre>结果:
<pre class="brush:php;toolbar:false">['klvchen', 'jack', 'james', 'lily', 'lucy'] a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] del a print(a)</pre>结果:
<pre class="brush:php;toolbar:false">NameError: name 'a' is not defined</pre>注意:del a 把列表a从内存删除了,所以打印 a 列表程序会报错
列表元素的统计
<pre class="brush:php;toolbar:false">list = ['a', 'a', 'b', 'c'] res = list.count('a') print(res)</pre>结果:
<pre class="brush:php;toolbar:false">2</pre>列表的排序
sort 方法
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] print(a) a.sort() print(a)</pre>结果:
<pre class="brush:php;toolbar:false">['klvchen', 'tom', 'jack', 'james', 'lily', 'lucy'] ['jack', 'james', 'klvchen', 'lily', 'lucy', 'tom']</pre>reverse 方法
<pre class="brush:php;toolbar:false">a = ["klvchen", "tom", "jack", "james", "lily", "lucy"] print(a) a.reverse() print(a)</pre>结果:
<pre class="brush:php;toolbar:false">['klvchen', 'tom', 'jack', 'james', 'lily', 'lucy'] ['lucy', 'lily', 'james', 'jack', 'tom', 'klvchen']</pre>您可能感兴趣的文章:
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