insert(-1,'a')
时间: 2024-01-15 13:03:24 浏览: 77
If we assume that we are inserting the value 'a' in a list, then the insert(-1,'a') method will insert the value 'a' at the second last position of the list.
For example:
```
my_list = [1, 2, 3, 4, 5]
my_list.insert(-1, 'a')
print(my_list)
```
Output:
```
[1, 2, 3, 'a', 4, 5]
```
Here, the value 'a' is inserted at the second last position of the list, which is represented by the index -1.
相关问题
python df1.insert
df1.insert() is a method in pandas library of Python used to insert a column into a DataFrame at a specified position. It has the following syntax:
```python
df1.insert(loc, column, value, allow_duplicates=False)
```
- loc: The position at which the new column should be inserted.
- column: The name of the new column.
- value: The value to be inserted in the new column.
- allow_duplicates (optional): Whether to allow duplicate column names. By default, it is set to False.
For example, let's say we have a DataFrame `df1`:
```python
import pandas as pd
data = {'Name': ['John', 'Emma', 'Alex'],
'Age': [28, 25, 32]}
df1 = pd.DataFrame(data)
print(df1)
```
Output:
```
Name Age
0 John 28
1 Emma 25
2 Alex 32
```
To insert a new column named "Salary" at position 1 with values [5000, 6000, 7000], we can use the `df1.insert()` method:
```python
df1.insert(1, "Salary", [5000, 6000, 7000])
print(df1)
```
Output:
```
Name Salary Age
0 John 5000 28
1 Emma 6000 25
2 Alex 7000 32
```
The new column "Salary" is inserted at position 1, shifting the existing columns to the right.
Linux ls-a
在Linux系统中,ls -a是一个常用的命令,用于列出当前目录下的所有文件,包括以.开头的隐藏文件。\[1\]这个命令可以帮助用户查看当前目录下的所有文件,包括隐藏文件,以便更好地管理和操作文件。同时,ls -a命令还可以与其他命令结合使用,例如ls -al可以列出当前目录下文件的详细信息。\[1\]所以,当你在Linux系统中使用ls -a命令时,你将会看到当前目录下的所有文件,包括隐藏文件。
#### 引用[.reference_title]
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