在Python数据帧中查找?
我有一个数据帧df1:在Python数据帧中查找?,python,python-3.x,pandas,dataframe,Python,Python 3.x,Pandas,Dataframe,我有一个数据帧df1: Month 1 3 March April 2 4 5 我有另一个数据帧df2: Month Name 1 January 2 February 3 March 4 April 5 May 如果我想用df2中相应的名称替换df1的整数值,我可以使用什么样的查找函数 我想以此作为我的df1: Month January March March April February May 一种替代方法
Month
1
3
March
April
2
4
5
我有另一个数据帧df2:
Month Name
1 January
2 February
3 March
4 April
5 May
如果我想用df2中相应的名称替换df1的整数值,我可以使用什么样的查找函数
我想以此作为我的df1:
Month
January
March
March
April
February
May
一种替代方法是与函数一起使用:
def repl(x, lookup=dict(zip(df2.Month.astype(str), df2.Name))):
return lookup.get(x, x)
df['Month'] = df['Month'].map(repl)
print(df)
输出
替换它
你可以使用和然后。只需小心将字符串映射到字符串,或者像这里一样,将数字映射到数字:
month_name = df2.set_index('Month')['Name']
df1['Month'] = pd.to_numeric(df1['Month'], errors='coerce').map(month_name)\
.fillna(df1['Month'])
print(df1)
Month
0 January
1 March
2 March
3 April
4 February
5 April
6 May
您也可以使用,但这是。将地图与系列一起使用,只需确保您的数据类型匹配:
mapper = df2.set_index(df2['Month'].astype(str))['Name']
df1['Month'].map(mapper).fillna(df1['Month'])
输出:
0 January
1 March
2 March
3 April
4 February
5 April
6 May
Name: Month, dtype: object
如果它们的顺序如示例所示,为什么不简单地使用df1['Month']=df2['Name']呢?它们的顺序不同。刚刚做了编辑。谢谢我试过了df1=df1.replacedictzipdf2.Month.astypestr,df2.Name,但它不起作用。当我打印df1时,我得到原始值。
mapper = df2.set_index(df2['Month'].astype(str))['Name']
df1['Month'].map(mapper).fillna(df1['Month'])
0 January
1 March
2 March
3 April
4 February
5 April
6 May
Name: Month, dtype: object