Python: dapatkan jumlah frekuensi berdasarkan dua kolom (variabel) di pandas dataframe beberapa baris appers

Halo Saya memiliki dataframe berikut.

    Group           Size

    Short          Small
    Short          Small
    Moderate       Medium
    Moderate       Small
    Tall           Large

Saya ingin menghitung frekuensi berapa kali baris yang sama muncul di dataframe.

    Group           Size      Time

    Short          Small        2
    Moderate       Medium       1 
    Moderate       Small        1
    Tall           Large        1

Anda dapat menggunakan groupby's size:

In [11]: df.groupby(["Group", "Size"]).size()
Out[11]:
Group     Size
Moderate  Medium    1
          Small     1
Short     Small     2
Tall      Large     1
dtype: int64

In [12]: df.groupby(["Group", "Size"]).size().reset_index(name="Time")
Out[12]:
      Group    Size  Time
0  Moderate  Medium     1
1  Moderate   Small     1
2     Short   Small     2
3      Tall   Large     1

Perbarui setelah pandas 1.1value_countssekarang menerima beberapa kolom

df.value_counts(["Group", "Size"])

Anda juga bisa mencoba pd.crosstab()

Group           Size

Short          Small
Short          Small
Moderate       Medium
Moderate       Small
Tall           Large

pd.crosstab(df.Group,df.Size)


Size      Large  Medium  Small
Group                         
Moderate      0       1      1
Short         0       0      2
Tall          1       0      0

EDIT: Untuk mendapatkan hasil Anda

pd.crosstab(df.Group,df.Size).replace(0,np.nan).\
     stack().reset_index().rename(columns={0:'Time'})
Out[591]: 
      Group    Size  Time
0  Moderate  Medium   1.0
1  Moderate   Small   1.0
2     Short   Small   2.0
3      Tall   Large   1.0

Kemungkinan lain menggunakan .pivot_table()danaggfunc='size'

df_solution = df.pivot_table(index=['Group','Size'], aggfunc='size')