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py_base.Rmd
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py_base.Rmd
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---
title: python基础
author: 高文欣
date: "`r Sys.Date()`"
output:
bookdown::gitbook:
split_by: none
split_bib: TRUE
df_print: paged
bibliography: refs/add.bib
---
# python基础复习
## pop
这几个要记住,哈哈
还是切片那里的
```r
sentence=['All', 'good', 'things', 'come', 'to' ,'those', 'who', 'wait.']
print("默认为 index=-1,删除最后一个列表值:",sentence.pop(-1),"\n")
print("默认删除最后一个列表值: ",sentence.pop(),"\n")
print("删除第一个元素:",sentence.pop(0),"\n")
print("删除第三个元素:",sentence.pop(2),"\n")print("输出剩余元素:",sentence)
```
### python切片复习
object[start_index:end_index:step]
step为正就是从左往右取值
step为负就是从右往左取值
不包括end_index
参考[csdn](https://www.jianshu.com/p/15715d6f4dad)
```r
a=['1','2','3']
c=a[::-1]
c
#['3', '2', '1']
```
需要记住的几个
```r
a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>>a[:] #从左往右
>>> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>>a[::]#从左往右
>>> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>>a[::-1]#从右往左
>>> [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
```