Python|熊猫 dataframe.insert()

Pandas 插入方法允许用户在数据框或系列（一维数据框）中插入一列。也可以通过下面的方法在数据框中手动插入一列，但是这里没有太大的自由度。
例如，即使列位置也无法确定，因此插入的列总是插入到最后一个位置。
句法：

DataFrameName.insert(loc, column, value, allow_duplicates = False)

参数：

loc: loc is an integer which is the location of column where we want to insert new column. This will shift the existing column at that position to the right. 
column: column is a string which is name of column to be inserted. 
value: value is simply the value to be inserted. It can be int, string, float or anything or even series / List of values. Providing only one value will set the same value for all rows. 
allow_duplicates : allow_duplicates is a boolean value which checks if column with same name already exists or not. 
 

从此处找到使用的 csv 文件的链接。

插入具有静态值的列：

Python3

# importing pandas module
import pandas as pd
  
# reading csv file
data = pd.read_csv("pokemon.csv")
  
# displaying  dataframe - Output 1
data.head()

输出：

插入列后：

Python3

# importing pandas module
import pandas as pd
 
# reading csv file
data = pd.read_csv("pokemon.csv")
 
# displaying  dataframe - Output 1
data.head()
 
# inserting column with static value in data frame
data.insert(2, "Team", "Any")
 
# displaying data frame again - Output 2
data.head()

为每一行传递具有不同值的系列：

在此示例中，创建了一个系列，并通过 for 循环将一些值传递给该系列。之后，将系列传递给 pandas 插入函数，以将系列附加到数据框中并传递值。

Python

# importing pandas module
import pandas as pd
 
# creating a blank series
Type_new = pd.Series([])
 
# reading csv file
data = pd.read_csv("pokemon.csv")
 
 
# running a for loop and assigning some values to series
for i in range(len(data)):
    if data["Type"][i] == "Grass":
        Type_new[i]="Green"
 
    elif data["Type"][i] == "Fire":
        Type_new[i]="Orange"
 
    elif data["Type"][i] == "Water":
        Type_new[i]="Blue"
 
    else:
        Type_new[i]= data["Type"][i]
 
         
# inserting new column with values of list made above       
data.insert(2, "Type New", Type_new)
 
# list output
data.head()

输出：