R, Python 분석과 프로그래밍의 친구 (by R Friend)

# importing libraries

import numpy as np

import pandas as pd

import matplotlib.pyplot as plt

import seaborn as sns

plt.rcParams['figure.figsize'] = [10, 8] # setting figure size

# loading 'iris' dataset from seaborn

iris = sns.load_dataset('iris')

iris.shape

(150, 5)

iris.head()

iris.groupby('species').size()

species setosa 50 versicolor 50 virginica 50 dtype: int64

  (1) matplotlib 으로 그룹별 산점도 그리기 (scatter plot by groups via matplotlib)

# Scatter plot with a different color by groups

groups = iris.groupby('species')

fig, ax = plt.subplots()

for name, group in groups:

    ax.plot(group.petal_length, 

            group.petal_width, 

            marker='o', 

            linestyle='',

            label=name)

ax.legend(fontsize=12, loc='upper left') # legend position

plt.title('Scatter Plot of iris by matplotlib', fontsize=20)

plt.xlabel('Petal Length', fontsize=14)

plt.ylabel('Petal Width', fontsize=14)

plt.show()

  (2) seaborn 으로 그룹별 산점도 그리기 (scatter plot by groups via seaborn)

# Scatter plot by Groups

sns.scatterplot(x='petal_length', 

                y='petal_width', 

                hue='species', # different colors by group

                style='species', # different shapes by group

                s=100, # marker size

                data=iris)

plt.show()

# error: AttributeError: module 'seaborn' has no attribute 'scatterplot' 

# solution: upgrade seaborn

pip install --upgrade seaborn

  (3) pandas로 그룹별 산점도 그리기 (scatter plot by groups via pandas)

# adding 'color' column

iris['color'] = np.where(iris.species == 'setosa', 'red', 

                         np.where(iris.species =='versicolor', 

                         'green', 

                         'blue'))

# scatter plot

iris.plot(kind='scatter',

          x='petal_length', 

          y='petal_width', 

          s=50, # marker size

          c=iris['color']) # marker color by group

plt.title('Scatter Plot of iris by pandas', fontsize=20)

plt.xlabel('Petal Length', fontsize=14)

plt.ylabel('Petal Width', fontsize=14)

plt.show()

# importing libraries

import numpy as np

import pandas as pd

import matplotlib.pyplot as plt

import seaborn as sns

plt.rcParams['figure.figsize'] = [12, 8] # setting figure size

# loading 'iris' dataset from seaborn

iris = sns.load_dataset('iris')

iris.shape

(150, 5) 

iris.head()

  (1) matplotlib을 사용한 산점도 (scatter plot by matplotlib)

# Basic Scatter Plot

plt.plot('petal_length',  # x

         'petal_width',  # y

         data=iris, 

         linestyle='none', 

         marker='o', 

         markersize=10,

         color='blue', 

         alpha=0.5)

plt.title('Scatter Plot of iris by matplotlib', fontsize=20)

plt.xlabel('Petal Length', fontsize=14)

plt.ylabel('Petal Width', fontsize=14)

plt.show()

# adding a rectangle, a circle

import matplotlib.patches as patches

import matplotlib.pyplot as plt

fig1 = plt.figure()

ax1 = fig1.add_subplot(111)

# (0) scatter plot

ax1.plot('petal_length', 'petal_width', data=iris, linestyle='none', marker='o')

# (1) adding a rectangle

ax1.add_patch(

    patches.Rectangle(

        (3, 1), # (x, y)

        2, # width

        1, # height

        alpha=0.2, 

        facecolor="blue", 

        edgecolor="black", 

        linewidth=2, 

        linestyle="solid", 

        angle=-10))

# (2) adding a circle

ax1.add_patch(

    patches.Circle(

        (1.5, 0.25), # (x, y)

        0.5, # radius

        alpha=0.2, 

        facecolor="red", 

        edgecolor="black", 

        linewidth=2, 

        linestyle='solid'))

# (3) adding a line

plt.plot([4, 6], [2.2, 1.1], color="green", lw=4, linestyle='solid')

plt.title("Adding a Rectangle, a Circle and a Line", fontsize=20)

plt.xlabel('Petal Length', fontsize=14)

plt.ylabel('Petal Width', fontsize=14)

plt.show()

  (2) seaborn을 사용한 산점도 (scatter plot by seaborn)

# Basic Scatter Plot by seaborn

sns.regplot(x=iris['petal_length'], 

           y=iris['petal_width'], 

           fit_reg=False) # no regression line

plt.title('Scatter Plot of iris by regplot()', fontsize=20)

plt.xlabel('Petal Length', fontsize=14)

plt.ylabel('Petal Width', fontsize=14)

plt.show()

# Scatter Plot with regression line by seaborn regplot()

sns.regplot(x=iris['petal_length'], 

           y=iris['petal_width'], 

           fit_reg=True) # default

plt.title('Scatter Plot with Regression Line by regplot()', fontsize=20)

plt.show()

# Control color of each marker based on X and Y values

iris_df = iris.copy()

# Adding a 'color' column based on x and y values

cutoff = (iris_df['petal_length']>2.5) & (iris_df['petal_width'] > 0.8)

iris_df['color'] = np.where(cutoff==True, "red", "blue")

# Scatter Plot with different colors based on X and Y values

sns.regplot(x=iris['petal_length'], 

           y=iris['petal_width'], 

           fit_reg=False, 

           scatter_kws={'facecolors': iris_df['color']}) # marker color

plt.title('Scatter Plot with different colors by X & Y values', fontsize=20)

plt.show()

# scatter plot by seaborn scatterplot()

ax = sns.scatterplot(x='petal_length', 

                     y='petal_width', 

                     alpha=0.5,

                     data=iris)

plt.title('Scatter Plot by seaborn', fontsize=20)

plt.show()

  (3) pandas를 사용한 산점도 (scatter plot by pandas)

iris.plot.scatter(x='petal_length', 

                  y='petal_width', 

                  s=50, # marker size

                  c='blue', 

                  alpha=0.5)

plt.title('Scatter Plot of iris by pandas', fontsize=20)

plt.xlabel('Petal Length', fontsize=14)

plt.ylabel('Petal Width', fontsize=14)

plt.show()

  (1) 원 그래프 (Pie Chart)

# importing library and set figure size

import matplotlib.pyplot as plt

plt.rcParams['figure.figsize'] = [12, 8]

# information of groups

group_names = ['Group_A', 'Group_B', 'Group_C']

group_sizes = [95, 54, 25]

group_colors = ['yellowgreen', 'lightskyblue', 'lightcoral']

group_explodes = (0.1, 0, 0) # explode 1st slice

# Pie chart

plt.pie(group_sizes, 

        explode=group_explodes, 

        labels=group_names, 

        colors=group_colors, 

        autopct='%1.2f%%', # second decimal place

        shadow=True, 

        startangle=90,

        textprops={'fontsize': 14}) # text font size

plt.axis('equal') #  equal length of X and Y axis

plt.title('Pie Chart of Market Share', fontsize=20)

plt.show()

  (2) 하위 그룹을 포함한 도넛 그래프 (Donut Chart with Subgraphs)

# importing library and set figure size

import matplotlib.pyplot as plt

plt.rcParams['figure.figsize'] = [12, 8]

 # info. of groups

group_names = ['Group_A', 'Group_B', 'Group_C']

group_sizes = [95, 54, 25]

# info. of subgroups

subgroup_names = ['A_1', 'A_2', 'A_3', 'A_4', 

                  'B_1', 'B_2', 'B_3', 

                  'C_1', 'C_2']

subgroup_sizes = [50, 30, 10, 5, 30, 20, 4, 20, 5]

# colors

a, b, c = [plt.cm.Reds, plt.cm.Greens, plt.cm.Blues]

# width

width_num = 0.4

# Outside Ring

fig, ax = plt.subplots()

ax.axis('equal')

pie_outside, _ = ax.pie(group_sizes, 

                        radius=1.3, 

                        labels=group_names, 

                        labeldistance=0.8,

                        colors=[a(0.6), b(0.6), c(0.6)])

plt.setp(pie_outside, 

         width=width_num, 

         edgecolor='white')

# Inside Ring

pie_inside, plt_labels, junk = \

    ax.pie(subgroup_sizes, 

           radius=(1.3 - width_num), 

           labels=subgroup_names, 

           labeldistance=0.75, 

           autopct='%1.1f%%', 

           colors=[a(0.5), a(0.4), a(0.3), a(0.2), 

                   b(0.5), b(0.4), b(0.3), 

                   c(0.5), c(0.4)])

plt.setp(pie_inside, 

         width=width_num, 

         edgecolor='white')

plt.title('Donut Plot with Subgroups', fontsize=20)

plt.show()

# importing packages

import numpy as np

import pandas as pd

import matplotlib.pyplot as plt

import seaborn as sns

plt.rcParams['figure.figsize'] = [10, 6]

# Loading 'tips' dataset from seaborn

tips = sns.load_dataset('tips')

tips.shape

(244, 7)

tips.head()

  (1) matplotlib으로 막대 그리프 그리기 (bar chart by matplotlib)

# Summary Statistics

tips_sum_by_day = tips.groupby('day').tip.sum()

tips_sum_by_day

day
Thur    171.83
Fri      51.96
Sat     260.40
Sun     247.39 

Name: tip, dtype: float64

label = ['Thur', 'Fri', 'Sat', 'Sun']

index = np.arange(len(label))

# Basic Bar Chart

plt.bar(index, tips_sum_by_day)

plt.title('Sum of Tips by Day', fontsize=20)

plt.xlabel('Day', fontsize=18)

plt.ylabel('Sum of Tips', fontsize=18)

plt.xticks(index, label, fontsize=15)

plt.show()

# bar color, transparency

plt.bar(label, tips_sum_by_day, 

        color='red', # color

        alpha=0.5) # transparency

plt.show()

# bar width, align

plt.bar(label, tips_sum_by_day, 

        width=0.5, # default: 0.8

        align='edge') # default: 'center'

plt.show()

# X tick labels rotation

plt.bar(index, tips_sum_by_day)

plt.xlabel('Day', fontsize=18)

plt.xticks(index, label, fontsize=15, 

           rotation=90) # when X tick labels are long

plt.show()

# Horizontal Bar Chart

plt.barh(index, tips_sum_by_day)

plt.title('Sum of Tips by Day', fontsize=18)

plt.ylabel('Day', fontsize=15)

plt.xlabel('Sum of Tips', fontsize=15)

plt.yticks(index, label, fontsize=13, rotation=0)

plt.show()

# summary by group

tips_sum_by_day_male = tips[tips['sex'] == 'Male'].groupby('day').tip.sum()

tips_sum_by_day_female = tips[tips['sex'] == 'Female'].groupby('day').tip.sum()

print('--Male--')

print(tips_sum_by_day_male);

print(' ')

print('--Female--')

print(tips_sum_by_day_female);

--Male--

day
Thur     89.41
Fri      26.93
Sat     181.95
Sun     186.78
Name: tip, dtype: float64
 
--Female--
day
Thur    82.42
Fri     25.03
Sat     78.45
Sun     60.61
Name: tip, dtype: float64

# Bar Chart by 2 categorical variables

# Stacked Bar Chart

label = ['Thur', 'Fri', 'Sat', 'Sun']

N = len(tips['day'].unique())

index = np.arange(N)

alpha = 0.5

p1 = plt.bar(index, tips_sum_by_day_male, color='b', alpha=alpha)

p2 = plt.bar(index, tips_sum_by_day_female, color='r', alpha=alpha,

             bottom=tips_sum_by_day_male) # stacked bar chart

plt.title('Stacked Bar Chart of Sum of Tips by Day & Sex', fontsize=20)

plt.ylabel('Sum of Tips', fontsize=18)

plt.xlabel('Day', fontsize=18)

plt.xticks(index, label, fontsize=15)

plt.legend((p1[0], p2[0]), ('Male', 'Female'), fontsize=15)

plt.show()

# Dodged Bar Chart (with same X coordinates side by side)

bar_width = 0.35

alpha = 0.5

p1 = plt.bar(index, tips_sum_by_day_male, 

             bar_width, 

             color='b', 

             alpha=alpha,

             label='Male')

p2 = plt.bar(index + bar_width, tips_sum_by_day_female, 

             bar_width, 

             color='r', 

             alpha=alpha,

             label='Female')

plt.title('Dodged Bar Chart of Sum of Tips by Day & Sex', fontsize=20)

plt.ylabel('Sum of Tips', fontsize=18)

plt.xlabel('Day', fontsize=18)

plt.xticks(index, label, fontsize=15)

plt.legend((p1[0], p2[0]), ('Male', 'Female'), fontsize=15)

plt.show()

  (2) seaborn 으로 막대 그래프 그리기 (bar chart by seaborn)

tips_sum_by_day_sex = pd.DataFrame(tips.groupby(['day', 'sex']).tip.sum())

tips_sum_by_day_sex = tips_sum_by_day_sex.reset_index()

tips_sum_by_day_sex

# sort dataframe by 'day' and 'sex' in descending order first

tips_sum_by_day_sex = tips_sum_by_day_sex.sort_values(by=['day', 'sex'], ascending=False)

tips_sum_by_day_sex

# then, calculate cumulative summation by 'day' group

tips_sum_by_day_sex['tip_cumsum'] = tips_sum_by_day_sex.groupby(['day'])['tip'].cumsum(axis=0)

tips_sum_by_day_sex

# atfer that, sort agian by 'day' and 'sex' in ascending order

tips_sum_by_day_sex = tips_sum_by_day_sex.sort_values(by=['day', 'sex'], ascending=True)

tips_sum_by_day_sex

# Stacked Bar Chart

sns.barplot(x='day', y='tip_cumsum', hue='sex', data=tips_sum_by_day_sex, 

           dodge=False) # stacked bar chart

plt.title('Stacked Bar Chart by Seaborn', fontsize='20')

plt.show()

# Dodged Bar Chart

sns.barplot(x='day', y='tip', hue='sex', data=tips_sum_by_day_sex) # default : dodge=True

plt.title('Dodged Bar Chart by Seaborn', fontsize=20)

plt.legend(fontsize=12)

plt.show()

  (3) pandas 로 막대 그래프 그리기 (bar chart by pandas)

# make a DataFrame

tips_sum_by_day = pd.DataFrame(tips.groupby('day').tip.sum())

tips_sum_by_day = tips_sum_by_day.reset_index()

# basic bar chart with a single column

tips_sum_by_day.plot.bar(x='day', y='tip', rot=0)

plt.show()

# making a DataFrame with 'day' and 'sex' groups

tips_sum_by_day_sex = pd.DataFrame(tips.groupby(['day', 'sex']).tip.sum())

tips_sum_by_day_sex = tips_sum_by_day_sex.reset_index()

# pivot

tips_sum_by_day_sex_pivot = \

    tips_sum_by_day_sex.pivot(index='day', 

                              columns='sex', 

                              values='tip')

tips_sum_by_day_sex_pivot

# Stacked Bar Chart by pandas

tips_sum_by_day_sex_pivot.plot.bar(stacked=True, rot=0)

plt.title('Stacked Bar Chart by Pandas', fontsize=20)

plt.show()

# Dodged Bar Chart by pandas

tips_sum_by_day_sex_pivot.plot(kind='bar', rot=0)

plt.title('Dodged Bar Chart by Pandas', fontsize=20)

plt.legend(fontsize='12')

plt.show()

import numpy as np

import pandas as pd

import matplotlib.pyplot as plt

import seaborn as sns

# Data Loading

iris = sns.load_dataset('iris')

iris.shape

(150, 5)

iris.head()

iris.groupby('species').size()

species
setosa        50
versicolor    50
virginica     50
dtype: int64

  (1) matplotlib.pyplot 으로 히스토그램 그리기

plt.hist(iris['sepal_width'], bins=10)

n, bins, patches = plt.hist(iris['sepal_width'], bins=10)

n, bins, patches

(array([ 4.,  7., 22., 24., 37., 31., 10., 11.,  2.,  2.]),
 array([2.  , 2.24, 2.48, 2.72, 2.96, 3.2 , 3.44, 3.68, 3.92, 4.16, 4.4 ]),
 <a list of 10 Patch objects>)

# Y axis as density

n, bins, patches = plt.hist(iris['sepal_width'], bins=10, density=True)

# facecolor, alpha

n, bins, patches = plt.hist(iris['sepal_width'], bins=10, 

                            density=True, 

                            facecolor='blue', 

                            alpha=0.5)

# Setting X, Y label and Title, axis

n, bins, patches = plt.hist(iris['sepal_width'], 

                            bins=10, 

                            density=True, 

                            facecolor='blue', 

                            alpha=0.5)

plt.xlabel('X bins')

plt.ylabel('Density')

plt.title('Histogram of Sepal Width')

plt.axis([1.5, 4.5, 0, 1.1])

plt.show()

  (2) seaborn 패키지로 히스토그램 그리기

sns.distplot(iris['sepal_width'])

plt.show()

# Kernel Density Curve with histogram

ax = sns.distplot(iris['sepal_width'], 

                      hist=True, 

                      kde=True, 

                      bins=10, 

                      color='blue', 

                      hist_kws={'edgecolor': 'gray'}, 

                      kde_kws={'linewidth': 2})

ax.set_title('Histogram of Sepal Width')

ax.set_xlabel('Sepal Width(cm)')

ax.set_ylabel('Density')

plt.show()

# Kernel Density Estimate Plot

sns.kdeplot(iris['sepal_width'],  

               shade=True, 

               bw=2, 

               label="Sepal Width")

plt.legend()

plt.show()

  (3) pandas.DataFrame.hist 를 이용한 히스토그램 그리기

# Histogram by pandas.DataFrame.hist

iris['sepal_width'].hist(bins=10, grid=False)

plt.show()

import numpy as np

import pandas as pd

from sklearn import datasets, linear_model

diabetes = datasets.load_diabetes()

diabetes.DESCR 

'Diabetes dataset

================

Notes

-----

Ten baseline variables, age, sex, body mass index, average blood

npressure, and six blood serum measurements were obtained for each of n =442 diabetes patients, as well as the response of interest, a\nquantitative measure of disease progression one year after baseline.\n\nData Set Characteristics:\n\n  :Number of Instances: 442\n\n  :Number of Attributes: First 10 columns are numeric predictive values\n\n  :Target: Column 11 is a quantitative measure of disease progression one year after baseline\n\n  :Attributes:\n    :Age:\n    :Sex:\n    :Body mass index:\n    :Average blood pressure:\n    :S1:\n    :S2:\n    :S3:\n    :S4:\n    :S5:\n    :S6:\n\nNote: Each of these 10 feature variables have been mean centered and scaled by the standard deviation times `n_samples` (i.e. the sum of squares of each column totals 1).\n\nSource URL:\nhttp://www4.stat.ncsu.edu/~boos/var.select/diabetes.html\n\nFor more information see:\nBradley Efron, Trevor Hastie, Iain Johnstone and Robert Tibshirani (2004) "Least Angle Regression," Annals of Statistics (with discussion), 407-499.\n(http://web.stanford.edu/~hastie/Papers/LARS/LeastAngle_2002.pdf)\n'

diabetes.feature_names

['age', 'sex', 'bmi', 'bp', 's1', 's2', 's3', 's4', 's5', 's6']

diabetes.target[:5]

array([151.,  75., 141., 206., 135.])

# Make a DataFrame of Y ('target')

diabetes_Y = pd.DataFrame(diabetes.target, columns = ['target'])

diabetes_Y[:5]

# Make a DataFrame of X with age, sex, bmi

diabetes_X = pd.DataFrame(diabetes.data[:, 0:3], 

                          columns = ['age', 'sex', 'bmi']) # age, sex, bmi

diabetes_X[:5]

diabetes_df = pd.concat([diabetes_Y, diabetes_X], axis=1)

diabetes_df[:5]

diabetes_df['grp'] = np.where(diabetes_df['sex'] > 0, 'M', 'F')

diabetes_df.drop(columns=['sex'], inplace=True) 

diabetes_df[:3]

# UDF of linear regression model

def lin_regress(data, yvar, xvars):

    # output, input variables

    Y = data[yvar]

    X = data[xvars]

    # Create linear regression object

    linreg = linear_model.LinearRegression()

    # Fit the linear regression model

    model = linreg.fit(X, Y)

    # Get the intercept and coefficients

    intercept = model.intercept_

    coef = model.coef_

    result = [intercept, coef]

    return result

# GroupBy

grouped = diabetes_df.groupby('grp')

# Apply the UDF of linear regression model by Group

lin_reg_coef = grouped.apply(lin_regress, 'target', ['age', 'bmi'])

lin_reg_coef

grp
F    [152.40684676047456, [23.199210147823813, 814....
M    [148.21507864445124, [291.7563226838977, 1092.... 

dtype: object 

lin_reg_coef['M']

[148.21507864445124, array([ 291.75632268, 1092.80118705])]

lin_reg_coef['F']

[152.40684676047456, array([ 23.19921015, 814.50932703])]

import numpy as np

import pandas as pd

from pandas import DataFrame

# making DataFrame with 4 random variables

np.random.seed(123) # for reproducibility

df= DataFrame(np.random.randn(10, 4), 

                    columns=['a', 'b', 'c', 'd'])

# setting index with 2 group, 'grp1' and 'grp2'

df['group'] = ['grp1', 'grp1', 'grp1', 'grp1', 'grp1', 

                  'grp2', 'grp2', 'grp2', 'grp2', 'grp2']

df = df.set_index('group')

df

  (1) 'd' 변수와 나머지 모든 변수 간 그룹 별 상관계수 구하기 : x.corrwith(x['d'])

# correlation with columns: corrwith()

corr_with_d = lambda x: x.corrwith(x['d'])

grouped = df.groupby('group')

grouped.apply(corr_with_d) 

  (2) 'a'변수와 'd'변수 간 그룹 별 상관계수 구하기 : g['a'].corr[g['d'])

# inter-column correlation: corr()

corr_a_d = lambda g: g['a'].corr(g['d'])

grouped = df.groupby('group')

DataFrame(grouped.apply(corr_a_d))

import numpy as np

import pandas as pd

from pandas import DataFrame

np.random.seed(123)

df = DataFrame({'col_1': np.random.randint(20, size=20), 

                      'col_2': np.random.randn(20)})

df

  (1) pd.cut : 동일 길이로 나누어서 범주 만들기(equal-length buckets categorization)

factor_col_1 = pd.cut(df.col_1, 4)

factor_col_1

0 (9.5, 14.25]

1     (-0.019, 4.75]
2     (-0.019, 4.75]
3        (4.75, 9.5]
4      (14.25, 19.0]
5      (14.25, 19.0]
6       (9.5, 14.25]
7     (-0.019, 4.75]
8     (-0.019, 4.75]
9      (14.25, 19.0]
10     (14.25, 19.0]
11       (4.75, 9.5]
12    (-0.019, 4.75]
13      (9.5, 14.25]
14    (-0.019, 4.75]
15     (14.25, 19.0]
16     (14.25, 19.0]
17      (9.5, 14.25]
18    (-0.019, 4.75]
19    (-0.019, 4.75]
Name: col_1, dtype: category
Categories (4, interval[float64]): [(-0.019, 4.75] < (4.75, 9.5] < (9.5, 14.25] < (14.25, 19.0]]

grouped_col_1 = df.col_1.groupby(factor_col_1)

grouped_col_1.agg(['count', 'mean', 'std', 'min', 'max'])

def summary_func(group):

    return {'count': group.count(), 

             'mean': group.mean(), 

             'std': group.std(), 

             'min': group.min(), 

             'max': group.max()}

grouped_col_1.apply(summary_func)

col_1                
(-0.019, 4.75]  count     8.000000
                max       4.000000
                mean      1.125000
                min       0.000000
                std       1.457738
(4.75, 9.5]     count     2.000000
                max       9.000000
                mean      7.500000
                min       6.000000
                std       2.121320
(9.5, 14.25]    count     4.000000
                max      14.000000
                mean     12.750000
                min      10.000000
                std       1.892969
(14.25, 19.0]   count     6.000000
                max      19.000000
                mean     17.000000
                min      15.000000
                std       1.788854
Name: col_1, dtype: float64

grouped_col_1.apply(summary_func).unstack()

  (2) pd.qcut() : 동일 개수로 나누어서 범주 만들기 (equal-size buckets categorization)

bucket_qcut_col_2 = pd.qcut(df.col_2, 4, labels=False)

bucket_qcut_col_2

0     3
1     3
2     0
3     2
4     1
5     3
6     2
7     0
8     1
9     3
10    3
11    0
12    0
13    1
14    1
15    1
16    2
17    2
18    0
19    2
Name: col_2, dtype: int64

bucket_qcut_label_col_2 = pd.qcut(df.col_2, 4, labels=np.arange(4, 0, -1))

bucket_qcut_label_col_2

0     1
1     1
2     4
3     2
4     3
5     1
6     2
7     4
8     3
9     1
10    1
11    4
12    4
13    3
14    3
15    3
16    2
17    2
18    4
19    2

Name: col_2, dtype: category
Categories (4, int64): [4 < 3 < 2 < 1]

grouped = df.col_2.groupby(bucket_qcut_label_col_2)

grouped.apply(summary_func).unstack()

 import numpy as np

 import pandas as pd

 from pandas import DataFrame

 df = DataFrame({'group_1': ['a', 'a', 'a', 'a', 'a',  

                                      'b', 'b', 'b', 'b', 'b',], 

                       'group_2': ['c', 'c', 'c', 'd', 'd', 

                                     'e', 'e', 'e', 'f', 'f'], 

                       'col': [1, 2, np.NaN, 4, np.NaN, 

                              6, 7, np.NaN, 9, 10]})

 df

  (a) 그룹 별 NaN이 아닌 원소의 개수 구하여 데이터프레임에 새로운 칼럼 추가하기

# 'count' grouped by (['group_1', 'group_2'])

 df['count_col'] = df.groupby(['group_1', 'group_2']).col.transform('count')

 df

  (b) 그룹 별 NaN이 아닌 원소의 합을 구하여 데이터프레임에 새로운 칼럼 추가하기

 # 'sum' grouped by (['group_1', 'group_2'])

 df['sum_col'] = df.groupby(['group_1', 'group_2']).col.transform('sum')

 df

  (c) 그룹 별 NaN이 아닌 원소 중 최대값을 구하여 데이터프레임에 새로운 칼럼 추가하기

 # 'max' grouped by (['group_1', 'group_2'])

 df['max_col'] = df.groupby(['group_1', 'group_2']).col.transform('max')

 df

import pandas as pd

import numpy as np

df = pd.DataFrame({'grp_col' : ['a', 'a', 'a', 'a', 'a', 'b', 'b', 'b', 'b', 'b'], 

                   'val' : np.arange(10)+1,                   

                   'weight' : [0.0, 0.1, 0.2, 0.3, 0.4, 0.0, 0.1, 0.2, 0.3, 0.4]})

df

  (1) GroupBy 를 활용하여 그룹 별 가중 평균 구하기

# group weighted average by category

grouped = df.groupby('grp_col')

weighted_avg_func = lambda g:np.average(g['val'], weights=g['weight'])

grouped.apply(weighted_avg_func)

grp_col
a    4.0
b    9.0
dtype: float64

 (2) 수작업으로 그룹 별 가중 평균 구하기 (Split -> Apply -> Combine) 

# split

df_a = df[df['grp_col']=='a']

df_b = df[df['grp_col']=='b']

 df_a

 df_b

# apply

weighted_avg_a = sum((df_a['val']*df_a['weight']))/sum(df_a['weight'])

weighted_avg_b = sum((df_b['val']*df_b['weight']))/sum(df_b['weight'])

 weighted_avg_a

4.0

 weighted_avg_b

9.0

# combine

weighted_avg_ab = pd.DataFrame({'grp_col': ['a', 'b'], 

                               'weighted_average': [weighted_avg_a, weighted_avg_b]})

weighted_avg_ab