How to create a new dataframe with the same value and get max min in each dataframe-CodePudding

Hi i got the dataframe like this

data = [(1,"tom", 23),
        (1,"nick", 12),
        (1,"jim",24),
        (2,"tom", 44),
        (2,"nick", 56),
        (2,"jim",77),
        (3, "tom", 88),
        (3, "nick", 10),
        (3, "jim", 13),
        ]
df = pd.DataFrame(data,columns=['class', 'Name','Number'])

output of the dataframe

   class  Name  Number
0      1   tom      23
1      1  nick      12
2      1   jim      24
3      2   tom      44
4      2  nick      56
5      2   jim      77
6      3   tom      88
7      3  nick      10
8      3   jim      13

i want to loop and get a new dataframe with the same class. The output should be like this

   class  Name  Number
0      1   tom      23
1      1  nick      12
2      1   jim      24

max_number_class_1 = 23

   class  Name  Number
3      2   tom      44
4      2  nick      56
5      2   jim      77

max_number_class_2 = 77


   class  Name  Number
6      3   tom      88
7      3  nick      10
8      3   jim      13

max_number_class_3 = 88

Thank you very much for helping me !

CodePudding user response：

You could just filter using

dfs = [df[df['class'].eq(key)] for key in df['class'].unique()]

This gives you the desired result as a list.

CodePudding user response：

It's not very neat but hopefully will serve the purpose.

df_list= []
for i in df['class'].unique():
    grouped = df.groupby(['class'])
    df_class= grouped.get_group(i)
    df_list.append(df_class)
    
for j in range (len(df_list)):
    print(df_list[j])
    print('The Maximum number in this class is',df_list[j]['Number'].max())
    print('The minimum number in this class is',df_list[j]['Number'].min())
    print()

The output looks like this:

    class  Name  Number
0      1   tom      23
1      1  nick      12
2      1   jim      24
The Maximum number in this class is 24
The minimum number in this class is 12

   class  Name  Number
3      2   tom      44
4      2  nick      56
5      2   jim      77
The Maximum number in this class is 77
The minimum number in this class is 44

   class  Name  Number
6      3   tom      88
7      3  nick      10
8      3   jim      13
The Maximum number in this class is 88
The minimum number in this class is 10

CodePudding user response：

Here are a few ways:

1- List Comprehension

dfs = [df[df["Class"].eq(x)] for x in df["Class"].unique()]

for df in dfs:
    max_number = df.Number.max()
    class_number = df["Class"].head(1).squeeze()

    print(f"{df}\n")
    print(f"max_number_class_{class_number} = {max_number}\n")

   Class  Name  Number
0      1   tom      23
1      1  nick      12
2      1   jim      13

max_number_class_1 = 23

   Class  Name  Number
3      2   tom      44
4      2  nick      56
5      2   jim      77

max_number_class_2 = 77

   Class  Name  Number
6      3   tom      88
7      3  nick      10
8      3   jim      13

max_number_class_3 = 88

2- Dictionary Comprehension

df_mapping = {x: df[df["Class"].eq(x)] for x in df["Class"].unique()}

for key in df_mapping.keys():
    max_number = df_mapping[key].Number.max()
    class_number = df_mapping[key]["Class"].head(1).squeeze()

    print(f"{df_mapping[key]}\n")
    print(f"max_number_class_{class_number} = {max_number}\n")

   Class  Name  Number
0      1   tom      23
1      1  nick      12
2      1   jim      13

max_number_class_1 = 23

   Class  Name  Number
3      2   tom      44
4      2  nick      56
5      2   jim      77

max_number_class_2 = 77

   Class  Name  Number
6      3   tom      88
7      3  nick      10
8      3   jim      13

max_number_class_3 = 88

3- Numpy Split

dfs = np.split(df.sort_values("Class", ascending=True), len(df["Name"].unique()))

for df in dfs:
    max_number = df.Number.max()
    class_number = df["Class"].head(1).squeeze()

    print(f"{df}\n")
    print(f"max_number_class_{class_number} = {max_number}\n")

   Class  Name  Number
0      1   tom      23
1      1  nick      12
2      1   jim      13

max_number_class_1 = 23

   Class  Name  Number
3      2   tom      44
4      2  nick      56
5      2   jim      77

max_number_class_2 = 77

   Class  Name  Number
6      3   tom      88
7      3  nick      10
8      3   jim      13

max_number_class_3 = 88