根据条件在循环中创建多个df

Question

I need to create multiple dataframes from slices of a bigger dataframe in pandas based on a condition. The different dataframes have to be named on the basis of some row values of the big dataframe.

This is the big dataframe:

 Id  Valore
ID554    53.0
ID554    43.0
ID522    42.0
ID522    32.0
ID566    26.0

therefore the different dataframes have to be named ID554, ID522, ID566 and so on. I have tried this:

id=df['Id'].unique()
for a in id:
 a=df.loc[(df['ID']==a)]

it does not work though..

Answer 1

You can use .groupby :

dataframes = {}
for name, g in df.groupby("Id"):
    dataframes[name] = g

# print the data:
for k, v in dataframes.items():
    print("Name:", k)
    print("-" * 80)
    print(v)
    print()

Prints:

Name: ID522
--------------------------------------------------------------------------------
      Id  Valore
2  ID522    42.0
3  ID522    32.0

Name: ID554
--------------------------------------------------------------------------------
      Id  Valore
0  ID554    53.0
1  ID554    43.0

Name: ID566
--------------------------------------------------------------------------------
      Id  Valore
4  ID566    26.0

Answer 2

Use exec

df = pd.DataFrame({"Id":["ID554","ID554","ID522","ID522","ID566"],"Valore":[53,43,42,32,26]})

for i in df.Id.unique():
    exec(f"{i} = df[df.Id == i]")

Following code will make different dataframes and save it in different variables with the name of its ID.

OUTPUTS:

print(ID522)

          Id  Valore
    2  ID522      42
    3  ID522      32

print(ID554)

       Id  Valore
    0  ID554      53
    1  ID554      43

print(ID566)

       Id  Valore
    4  ID566      26