How to create a dictionary by grouping key for different values in python?-CodePudding

'I have a dataframe

df
      Key Value
0     key1 value1
1     key2 value2
2     key3 value3
3     key1 value4
4     key5 value5
5     key2 value1
6     key3 value2
...
n     keyn valuen

I want to group all the values for the same key and hence tried to convert to dictionary as

pd.Series(df.Value.values,index=df.Key).to_dict()

But this would overwrite the key's value with the latest record

for eg

{'key1':'value5','key2':'value1','key3':'value2','key5':'value5'}

Instead of

{'key1':['value1','value4','value5'],'key2':['value2','value1'],'key3':['value3','value2'],'key5':'value5'}

I tried changing the orientation of to_dict as

pd.Series(df.Value.values,index=df.Key).to_dict('list')

But it threw the error

TypeError: unsupported type: <class 'str'>

CodePudding user response：

You can aggregate the values as a list on groupby, then export as dict:

df.groupby('Key')['Value'].agg(list).to_dict()

Result:

{'key1': ['value1', 'value4'],
 'key2': ['value2', 'value1'],
 'key3': ['value3', 'value2'],
 'key5': ['value5']}

CodePudding user response：

This