pip install pandasvault

import pandas as pd
import numpy as np
import pandasvault as pv

"""TABLE PROCESSING"""
df = pv.list_shuff(["target","c","d"],df)
df = pv.reduce_mem_usage(df)

"""TABLE EXPLORATION"""
df = pv.corr_list(df)
df = pv.missing_data(df)

"""FEATURE PROCESSING"""
df = pv.drop_corr(df, thresh=0.1,keep_cols=["target"])
df = pv.replace_small_cat(df,["cat"])
qconstant_col = pv.constant_feature_detect(data=df,threshold=0.9)
df_train, scl = pv.scaler(df,target="target",cols_ignore=["a"],type="MinMax")
df_test = pv.scaler(df_test,scaler=scl,train=False, target="target",cols_ignore=["a"])
df = pv.impute_null_with_tail(df,cols=df.columns)
index,para = pv.outlier_detect(df,"a",threshold=0.5,method="IQR")
df = pv.windsorization(data=df,col='a',para=para,strategy='both')
df = pv.impute_outlier(data=df,col='a', outlier_index=index,strategy='mean')

"""FEATURE EXTRACTION"""
df = pv.auto_dummy(df, unique=3)
df = pv.binarise_empty(df, frac=0.6)
df = pv.polynomials(df, ["a","b"]) 
df = pv.transformations(df,["a","b"])
df = pv.pca_feature(df,variance_or_components=0.80,drop_cols=["target","a"])
df = pv.multiple_lags(df, start=1, end=2,columns=["a","target"])
df = pv.multiple_rolling(df, columns=["a"])
df = pv.date_features(df, date="date_fake")
df['distance_central'] = df.apply(pv.haversine_distance,axis=1)

"""MODEL VALIDATION"""
scores = pv.classification_scores(y_test, y_predict, y_prob)

!pip install pandasvault

import pandas as pd
import numpy as np
import pandasvault as pv

np.random.seed(1)
"""quick way to create a data frame for testing""" 
df_test = pd.DataFrame(np.random.randn(3, 4), columns=['a', 'b', 'c', 'd']) \
    .assign(target=lambda x: (x['b']+x['a']/x['d'])*x['c'])

import pandas as pd

def pd_config():
    options = {
        'display': {
            'max_colwidth': 25,
            'expand_frame_repr': False,  # Don't wrap to multiple pages
            'max_rows': 14,
            'max_seq_items': 50,         # Max length of printed sequence
            'precision': 4,
            'show_dimensions': False
        },
        'mode': {
            'chained_assignment': None   # Controls SettingWithCopyWarning
        }
    }

    for category, option in options.items():
        for op, value in option.items():
            pd.set_option(f'{category}.{op}', value)  # Python 3.6+

if __name__ == '__main__':
    pv.pd_config()

df = df_test.copy()
df["number"] = [3,10,1]

df_out = (
  df.style.format({"a":"${:.2f}", "target":"${:.5f}"})
 .hide_index()
 .highlight_min("a", color ="red")
 .highlight_max("a", color ="green")
 .background_gradient(subset = "target", cmap ="Blues")
 .bar("number", color = "lightblue", align = "zero")
 .set_caption("DF with different stylings")
) ; df_out

df1 = pd.util.testing.makeDataFrame() # contains random values
print("Contains missing values")
df2 = pd.util.testing.makeMissingDataframe() # contains missing values
print("Contains datetime values")
df3 = pd.util.testing.makeTimeDataFrame() # contains datetime values
print("Contains mixed values")
df4 = pd.util.testing.makeMixedDataFrame(); df4.head() # contains mixed values

## Lower-case all DataFrame column names 
df = df_test.copy() ; df
df.columns = ["A","BGs","c","dag","Target"]

df.columns = map(str.lower, df.columns); df

df = df_test.copy(); df

def front(self, n):
    return self.iloc[:, :n]

def back(self, n):
    return self.iloc[:, -n:]

pd.back = back
pd.front = front

pd.back(df,2)

df = df_test.copy(); df

test =  df.sample(frac=0.4)
train = df[~df.isin(test)].dropna(); train

df = df_test.head()
y = 'target'
X = [name for name in df.columns if name not in [y, 'd']]
print('y =', y)
print('X =', X)

df = df_test.copy()
df["category"] = np.where( df["target"]>1, "1",  "0")
df["k"] = df["category"].astype(str) +": " + df["d"].round(1).astype(str) 
df = df.append(df, ignore_index=True) ; df.head()

"""set display width, col_width etc for interactive pandas session""" 
pd.set_option('display.width', 200)
pd.set_option('display.max_colwidth', 20)
pd.set_option('display.max_rows', 100)
           
"""when you have an excel sheet with spaces in column names"""
df.columns = [c.lower().replace(' ', '_') for c in df.columns]

"""Add prefix to all columns"""
df.add_prefix("1_")

"""Add suffix to all columns"""
df.add_suffix("_Z")

"""Droping column where missing values are above a threshold"""
df.dropna(thresh = len(df)*0.95, axis = "columns") 

"""Given a dataframe df to filter by a series ["a","b"]:""" 
df[df['category'].isin(["1","0"])]

"""filter by multiple conditions in a dataframe df"""
df[(df['a'] >1) & (df['b'] <1)]

"""filter by conditions and the condition on row labels(index)"""
df[(df.a > 0) & (df.index.isin([0, 1]))]

"""regexp filters on strings (vectorized), use .* instead of *"""
df[df.category.str.contains(r'.*[0-9].*')]

"""logical NOT is like this"""
df[~df.category.str.contains(r'.*[0-9].*')]

"""creating complex filters using functions on rows"""
df[df.apply(lambda x: x['b'] > x['c'], axis=1)]

"""Pandas replace operation"""
df["a"].round(2).replace(0.87, 17, inplace=True)
df["a"][df["a"] < 4] = 19

"""Conditionals and selectors"""
df.loc[df["a"] > 1, ["a","b","target"]]

"""Selecting multiple column slices"""
df.iloc[:, np.r_[0:2, 4:5]] 

"""apply and map examples"""
df[["a","b","c"]].applymap(lambda x: x+1)

"""add 2 to row 3 and return the series"""
df[["a","b","c"]].apply(lambda x: x[0]+2,axis=0)

"""add 3 to col A and return the series"""
df.apply(lambda x: x['a']+1,axis=1)

""" Split delimited values in a DataFrame column into two new columns """
df['new1'], df['new2'] = zip(*df['k'].apply(lambda x: x.split(': ', 1)))

""" Doing calculations with DataFrame columns that have missing values
  In example below, swap in 0 for df['col1'] cells that contain null """ 
df['new3'] = np.where(pd.isnull(df['b']),0,df['a']) + df['c']

""" Exclude certain data type or include certain data types """
df.select_dtypes(exclude=['O','float'])
df.select_dtypes(include=['int'])

"""one liner to normalize a data frame""" 
(df[["a","b"]] - df[["a","b"]].mean()) / (df[["a","b"]].max() - df[["a","b"]].min())

"""groupby used like a histogram to obtain counts on sub-ranges of a variable, pretty handy""" 
df.groupby(pd.cut(df.a, range(0, 1, 2))).size()

"""use a local variable use inside a query of pandas using @"""
mean = df["a"].mean()
df.query("a > @mean")

"""Calculate the % of missing values in each column"""
df.isna().mean() 

"""Calculate the % of missing values in each row"""
rows = df.isna().mean(axis=1) ; df.head()

df = pd.util.testing.makeMixedDataFrame()
df.to_csv("data.csv") ; df

"""To avoid Unnamed: 0 when loading a previously saved csv with index"""
"""To parse dates"""
"""To set data types"""

df_out = pd.read_csv("data.csv", index_col=0,
                 parse_dates=['D'],
                 dtype={"c":"category", "B":"int64"}).set_index("D")

"""Copy data to clipboard; like an excel copy and paste
df = pd.read_clipboard()
"""

"""Read table from website
df = pd.read_html(url, match="table_name")
"""

""" Read pdf into dataframe ()
!pip install tabula
from tabula import read_pdf
df = read_pdf('test.pdf', pages='all')
"""
df_out.head()

df = df_test.copy()
df["cats"] = ["bad","good","excellent"]; df

import pandas as pd
from pandas.api.types import CategoricalDtype

print("Let's create our own categorical order.")
cat_type = CategoricalDtype(["bad", "good", "excellent"], ordered = True)
df["cats"] = df["cats"].astype(cat_type)

print("Now we can use logical sorting.")
df = df.sort_values("cats", ascending = True)

print("We can also filter this as if they are numbers.")
df[df["cats"] > "bad"]

df = df_test.head(); df
df.columns = ["a_l", "b_l", "c_r","d_r","target"]  ; df

df_out = df.filter(regex="_l",axis=1) ; df_out

df = df_test.copy()
df = df.append(df, ignore_index=True)
df["groupie"] = ["falcon","hawk","hawk","eagle","falcon","hawk"]; df

gbdf = df.groupby("groupie")
hawk = gbdf.get_group("hawk").mean(); hawk

df = df_test.copy()

cr1 = df["a"] > 0
cr2 = df["b"] < 0
cr3 = df["c"] > 0
cr4 = df["d"] >-1

df[cr1 & cr2 & cr3 & cr4]

df = df_test.copy(); df

import gc

def reduce_mem_usage(df):
    """ iterate through all the columns of a dataframe and modify the data type
        to reduce memory usage.        
    """
    start_mem = df.memory_usage().sum() / 1024**2
    print('Memory usage of dataframe is {:.2f} MB'.format(start_mem))
    
    for col in df.columns:
        col_type = df[col].dtype
        gc.collect()
        if col_type != object:
            c_min = df[col].min()
            c_max = df[col].max()
            if str(col_type)[:3] == 'int':
                if c_min > np.iinfo(np.int8).min and c_max < np.iinfo(np.int8).max:
                    df[col] = df[col].astype(np.int8)
                elif c_min > np.iinfo(np.int16).min and c_max < np.iinfo(np.int16).max:
                    df[col] = df[col].astype(np.int16)
                elif c_min > np.iinfo(np.int32).min and c_max < np.iinfo(np.int32).max:
                    df[col] = df[col].astype(np.int32)
                elif c_min > np.iinfo(np.int64).min and c_max < np.iinfo(np.int64).max:
                    df[col] = df[col].astype(np.int64)  
            else:
                if c_min > np.finfo(np.float16).min and c_max < np.finfo(np.float16).max:
                    df[col] = df[col].astype(np.float16)
                elif c_min > np.finfo(np.float32).min and c_max < np.finfo(np.float32).max:
                    df[col] = df[col].astype(np.float32)
                else:
                    df[col] = df[col].astype(np.float64)
        else:
            df[col] = df[col].astype('category')

    end_mem = df.memory_usage().sum() / 1024**2
    print('Memory usage after optimization is: {:.2f} MB'.format(end_mem))
    print('Decreased by {:.1f}%'.format(100 * (start_mem - end_mem) / start_mem))
    
    return df
df_out = pv.reduce_mem_usage(df); df_out

df = df_test.copy()
df["first_d"] = [0,1,2]
df["second_d"] = [4,1,9] ; df

def verify_primary_key(df, column_list):
    '''Verify if columns in column list can be treat as primary key'''

    return df.shape[0] == df.groupby(column_list).size().reset_index().shape[0]

verify_primary_key(df, ["first_d","second_d"])

df = df_test.copy(); df

def list_shuff(items, df):
    "Bring a list of columns to the front"
    cols = list(df)
    for i in range(len(items)):
        cols.insert(i, cols.pop(cols.index(items[i])))
    df = df.loc[:, cols]
    df.reset_index(drop=True, inplace=True)
    return df

df_out = pv.list_shuff(["target","c","d"],df); df_out

df = df_test.copy(); df

df_out = (df.assign(stringed = df["a"].astype(str),
            ounces = df["b"]*12,#                                     this will allow yo set a title
            galons = lambda df: df["a"]/128)
           .query("b > -1")
           .style.set_caption("Average consumption")) ; df_out

df = df_test.copy()
df[df>df.mean()]  = None ; df

# with line continuation character
df_out = df.dropna(subset=["b","c"],how="all") \
.loc[df["a"]>0] \
.round(2) \
.groupby(["target","b"]).max() \
.unstack() \
.fillna(0) \
.rolling(1).sum() \
.reset_index() \
.stack() \
.ffill().bfill() 

df_out

import os
os.makedirs("folder",exist_ok=True,); df_test.to_csv("folder/first.csv",index=False) ; df_test.to_csv("folder/last.csv",index=False)

import glob
files = glob.glob('folder/*.csv')
dfs = [pd.read_csv(fp) for fp in files]
df_out = pd.concat(dfs)

df_out

df = df_test.copy()
df["string_feature"] = ["1xZoo", "Safe7x", "bat4"]; df

substring = ["xZ","7z", "tab4"]

df_out = df[~df.string_feature.str.contains('|'.join(substring))]; df_out

df = df_test.head()
df["g"] = [[str(a)+lista for a in range(4)] for lista in ["a","b","c"]]; df

df_out = df.explode("g"); df_out.iloc[:5,:]

### Run above example first 
df = df_out.copy()

df_out['g'] = df_out.groupby(df_out.index)['g'].agg(list); df_out.head()

df = df_test.head()
df["g"] = [",".join([str(a)+lista for a in range(4)]) for lista in ["a","b","c"]]; df

df_out = df.assign(g = df["g"].str.split(",")).explode("g"); df_out.head()

df = df_test.head() 
df["gr"] = [1, 1 , 0] ;df

In [34]: gb.<TAB>  # noqa: E225, E999
gb.agg        gb.boxplot    gb.cummin     gb.describe   gb.filter     
gb.get_group  gb.height     gb.last       gb.median     gb.ngroups    
gb.plot       gb.rank       gb.std        gb.transform  gb.aggregate  
gb.count      gb.cumprod    gb.dtype      gb.first      gb.nth
gb.groups     gb.hist       gb.max        gb.min        gb.gender        
gb.prod       gb.resample   gb.sum        gb.var        gb.ohlc  
gb.apply      gb.cummax     gb.cumsum     gb.fillna          
gb.head       gb.indices    gb.mean       gb.name            
gb.quantile   gb.size       gb.tail       gb.weight

df_out = df.groupby('gr').agg([np.sum, np.mean, np.std]); df_out.iloc[:,:8]

df = df_test.copy(); df

def corr_list(df):

  return  (df.corr()
          .unstack()
          .sort_values(kind="quicksort",ascending=False)
          .drop_duplicates().iloc[1:]); df_out
          
pv.corr_list(df)

df = df_test.copy()
df[df>df.mean()]  = None ; df

def missing_data(data):
    "Create a dataframe with a percentage and count of missing values"
    total = data.isnull().sum().sort_values(ascending = False)
    percent = (data.isnull().sum()/data.isnull().count()*100).sort_values(ascending = False)
    return pd.concat([total, percent], axis=1, keys=['Total', 'Percent'])

pv.df_out = missing_data(df); df_out

df = df_test.copy()
df["a"].iloc[2] = df["a"].iloc[1]
df["b"].iloc[2] = df["b"].iloc[1] ; df

# Get a report of all duplicate records in a dataframe, based on specific columns
df_out = df[df.duplicated(['a', 'b'], keep=False)] ; df_out

df = df_test.copy(); df

from scipy.stats import skew

def display_skewness(data):
    '''show skewness information

        Parameters
        ----------
        data: pandas dataframe

        Return
        ------
        df: pandas dataframe
    '''
    numeric_cols = data.columns[data.dtypes != 'object'].tolist()
    skew_value = []

    for i in numeric_cols:
        skew_value += [skew(data[i])]
    df = pd.concat(
        [pd.Series(numeric_cols), pd.Series(data.dtypes[data.dtypes != 'object'].apply(lambda x: str(x)).values)
            , pd.Series(skew_value)], axis=1)
    df.columns = ['var_name', 'col_type', 'skew_value']

    return df

display_skewness(df)

df= df_test.copy(); df

def drop_corr(df, thresh=0.99,keep_cols=[]):
    df_corr = df.corr().abs()
    upper = df_corr.where(np.triu(np.ones(df_corr.shape), k=1).astype(np.bool))
    to_remove = [column for column in upper.columns if any(upper[column] > thresh)] ## Change to 99% for selection
    to_remove = [x for x in to_remove if x not in keep_cols]
    df_corr = df_corr.drop(columns = to_remove)
    return df.drop(to_remove,axis=1)

df_out = pv.drop_corr(df, thresh=0.1,keep_cols=["target"]); df_out

df = df_test.copy()
df = df.append([df]*2)
df["cat"] = ["bat","bat","rat","mat","mat","mat","mat","mat","mat"]; df

def replace_small_cat(df, columns, thresh=0.2, term="other"):
  for col in columns:

    # Step 1: count the frequencies
    frequencies = df[col].value_counts(normalize = True)

  # Step 2: establish your threshold and filter the smaller categories

    small_categories = frequencies[frequencies < thresh].index

    df[col] = df[col].replace(small_categories, "Other")
    
  return df

df_out = pv.replace_small_cat(df,["cat"]); df_out.head()

df = df_test.copy()
df["a"] = 3 

def constant_feature_detect(data,threshold=0.98):
    """ detect features that show the same value for the 
    majority/all of the observations (constant/quasi-constant features)
    
    Parameters
    ----------
    data : pd.Dataframe
    threshold : threshold to identify the variable as constant
        
    Returns
    -------
    list of variables names
    """
    
    data_copy = data.copy(deep=True)
    quasi_constant_feature = []
    for feature in data_copy.columns:
        predominant = (data_copy[feature].value_counts() / np.float(
                      len(data_copy))).sort_values(ascending=False).values[0]
        if predominant >= threshold:
            quasi_constant_feature.append(feature)
    print(len(quasi_constant_feature),' variables are found to be almost constant')    
    return quasi_constant_feature

# the original dataset has no constant variable
qconstant_col = pv.constant_feature_detect(data=df,threshold=0.9)
df_out = df.drop(qconstant_col, axis=1) ; df_out

### I will take care of outliers separately

df = df_test.copy()
df[df>df.mean()]  = None ; df

# Clean up missing values in multiple DataFrame columns
dict_fill = {'a': 4,
              'b': 3,
              'c': 5,
              'd': 9999,
              'target': "False"}
df = df.fillna(dict_fill) ;df

df = df_test.copy(); df

# Set DataFrame column values based on other column values
df.loc[(df['a'] >1 ) & (df['c'] <0), ['target']] = np.nan ;df

df = df_test.copy().assign(target=lambda row: row["a"].round(4).astype(str)+"SC"+row["b"].round(4).astype(str))
df["a"] = "TI4560L" + df["a"].round(4).astype(str) ; df

df_out = df.replace('[^0-9]+', '', regex=True); df_out

df= df_test.copy(); df

from sklearn.preprocessing import StandardScaler
from sklearn.preprocessing import MinMaxScaler

def scaler(df,scaler=None,train=True, target=None, cols_ignore=None, type="Standard"):

  if cols_ignore:
    hold = df[cols_ignore].copy()
    df = df.drop(cols_ignore,axis=1)
  if target:
    x = df.drop([target],axis=1).values #returns a numpy array
  else:
    x = df.values
  if train:
    if type=="Standard":
      scal = StandardScaler()
    elif type=="MinMax":
      scal = MinMaxScaler()
    scal.fit(x)
    x_scaled = scal.transform(x)
  else:
    x_scaled = scaler.transform(x)
  
  if target:
    df_out = pd.DataFrame(x_scaled, index=df.index, columns=df.drop([target],axis=1).columns)
    df_out[target]= df[target]
  else:
    df_out = pd.DataFrame(x_scaled, index=df.index, columns=df.columns)
  
  df_out = pd.concat((hold,df_out),axis=1)
  if train:
    return df_out, scal
  else:
    return df_out

df_out_train, scl = pv.scaler(df,target="target",cols_ignore=["a"],type="MinMax")
df_out_test = pv.scaler(df_test,scaler=scl,train=False, target="target",cols_ignore=["a"]); df_out_test

df = df_test.copy()
df[df>df.mean()]  = None ; df

def impute_null_with_tail(df,cols=[]):
    """
    replacing the NA by values that are at the far end of the distribution of that variable
    calculated by mean + 3*std
    """
    
    df = df.copy(deep=True)
    for i in cols:
        if df[i].isnull().sum()>0:
            df[i] = df[i].fillna(df[i].mean()+3*df[i].std())
        else:
            warn("Column %s has no missing" % i)
    return df    
  

df_out = pv.impute_null_with_tail(df,cols=df.columns); df_out

df = df_test.copy(); df

def outlier_detect(data,col,threshold=3,method="IQR"):
  
    if method == "IQR":
      IQR = data[col].quantile(0.75) - data[col].quantile(0.25)
      Lower_fence = data[col].quantile(0.25) - (IQR * threshold)
      Upper_fence = data[col].quantile(0.75) + (IQR * threshold)
    if method == "STD":
      Upper_fence = data[col].mean() + threshold * data[col].std()
      Lower_fence = data[col].mean() - threshold * data[col].std()   
    if method == "OWN":
      Upper_fence = data[col].mean() + threshold * data[col].std()
      Lower_fence = data[col].mean() - threshold * data[col].std() 
    if method =="MAD":
      median = data[col].median()
      median_absolute_deviation = np.median([np.abs(y - median) for y in data[col]])
      modified_z_scores = pd.Series([0.6745 * (y - median) / median_absolute_deviation for y in data[col]])
      outlier_index = np.abs(modified_z_scores) > threshold
      print('Num of outlier detected:',outlier_index.value_counts()[1])
      print('Proportion of outlier detected',outlier_index.value_counts()[1]/len(outlier_index))
      return outlier_index, (median_absolute_deviation, median_absolute_deviation)


    para = (Upper_fence, Lower_fence)
    tmp = pd.concat([data[col]>Upper_fence,data[col]<Lower_fence],axis=1)
    outlier_index = tmp.any(axis=1)
    print('Num of outlier detected:',outlier_index.value_counts()[1])
    print('Proportion of outlier detected',outlier_index.value_counts()[1]/len(outlier_index))
    
    return outlier_index, para
    

index,para = pv.outlier_detect(df,"a",threshold=0.5,method="IQR")
print('Upper bound:',para[0],'\nLower bound:',para[1])

# RUN above example first
df = df_test.copy(); df

def windsorization(data,col,para,strategy='both'):
    """
    top-coding & bottom coding (capping the maximum of a distribution at an arbitrarily set value,vice versa)
    """

    data_copy = data.copy(deep=True)  
    if strategy == 'both':
        data_copy.loc[data_copy[col]>para[0],col] = para[0]
        data_copy.loc[data_copy[col]<para[1],col] = para[1]
    elif strategy == 'top':
        data_copy.loc[data_copy[col]>para[0],col] = para[0]
    elif strategy == 'bottom':
        data_copy.loc[data_copy[col]<para[1],col] = para[1]  
    return data_copy


df_out = pv.windsorization(data=df,col='a',para=para,strategy='both'); df_out

## run the top two examples
df = df_test.copy(); df

df_out = df[~index] ; df_out

def impute_outlier(data,col,outlier_index,strategy='mean'):
    """
    impute outlier with mean/median/most frequent values of that variable.
    """

    data_copy = data.copy(deep=True)
    if strategy=='mean':
        data_copy.loc[outlier_index,col] = data_copy[col].mean()
    elif strategy=='median':
        data_copy.loc[outlier_index,col] = data_copy[col].median()
    elif strategy=='mode':
        data_copy.loc[outlier_index,col] = data_copy[col].mode()[0]   
        
    return data_copy
  
df_out = pv.impute_outlier(data=df,col='a', outlier_index=index,strategy='mean'); df_out

df = df_test.copy()
df["e"] = np.where(df["c"]> df["a"], 1,  2)

def auto_dummy(df, unique=15):
  # Creating dummies for small object uniques
  if len(df)<unique:
    raise ValueError('unique is set higher than data lenght')
  list_dummies =[]
  for col in df.columns:
      if (len(df[col].unique()) < unique):
          list_dummies.append(col)
          print(col)
  df_edit = pd.get_dummies(df, columns = list_dummies) # Saves original dataframe
  #df_edit = pd.concat([df[["year","qtr"]],df_edit],axis=1)
  return df_edit

df_out = pv.auto_dummy(df, unique=3); df_out

df = df_test.copy()
df[df>df.mean()]  = None ; df

def binarise_empty(df, frac=80):
  # Binarise slightly empty columns
  this =[]
  for col in df.columns:
      if df[col].dtype != "object":
          is_null = df[col].isnull().astype(int).sum()
          if (is_null/df.shape[0]) >frac: # if more than 70% is null binarise
              print(col)
              this.append(col)
              df[col] = df[col].astype(float)
              df[col] = df[col].apply(lambda x: 0 if (np.isnan(x)) else 1)
  df = pd.get_dummies(df, columns = this) 
  return df

df_out = pv.binarise_empty(df, frac=0.6); df_out

df = df_test.copy(); df

def polynomials(df, feature_list):
  for feat in feature_list:
    for feat_two in feature_list:
      if feat==feat_two:
        continue
      else:
       df[feat+"/"+feat_two] = df[feat]/(df[feat_two]-df[feat_two].min()) #zero division guard
       df[feat+"X"+feat_two] = df[feat]*(df[feat_two])

  return df

df_out = pv.polynomials(df, ["a","b"]) ; df_out

df = df_test.copy(); df

def transformations(df,features):
  df_new = df[features]
  df_new = df_new - df_new.min()

  sqr_name = [str(fa)+"_POWER_2" for fa in df_new.columns]
  log_p_name = [str(fa)+"_LOG_p_one_abs" for fa in df_new.columns]
  rec_p_name = [str(fa)+"_RECIP_p_one" for fa in df_new.columns]
  sqrt_name = [str(fa)+"_SQRT_p_one" for fa in df_new.columns]

  df_sqr = pd.DataFrame(np.power(df_new.values, 2),columns=sqr_name, index=df.index)
  df_log = pd.DataFrame(np.log(df_new.add(1).abs().values),columns=log_p_name, index=df.index)
  df_rec = pd.DataFrame(np.reciprocal(df_new.add(1).values),columns=rec_p_name, index=df.index)
  df_sqrt = pd.DataFrame(np.sqrt(df_new.abs().add(1).values),columns=sqrt_name, index=df.index)

  dfs = [df, df_sqr, df_log, df_rec, df_sqrt]

  df=  pd.concat(dfs, axis=1)

  return df

df_out = pv.transformations(df,["a","b"]); df_out.iloc[:,:8]

! pip install gplearn

df = df_test.copy(); df

from gplearn.genetic import SymbolicTransformer
function_set = ['add', 'sub', 'mul', 'div',
                'sqrt', 'log', 'abs', 'neg', 'inv','tan']

gp = SymbolicTransformer(generations=800, population_size=200,
                         hall_of_fame=100, n_components=10,
                         function_set=function_set,
                         parsimony_coefficient=0.0005,
                         max_samples=0.9, verbose=1,
                         random_state=0, n_jobs=6)

gen_feats = gp.fit_transform(df.drop("target", axis=1), df["target"]); df.iloc[:,:8]
df_out = pd.concat((df,pd.DataFrame(gen_feats, columns=["gen_"+str(a) for a in range(gen_feats.shape[1])])),axis=1); df_out.iloc[:,:8]

df =df_test.copy(); df

from sklearn.decomposition import PCA, IncrementalPCA

def pca_feature(df, memory_issues=False,mem_iss_component=False,variance_or_components=0.80,drop_cols=None):

  if memory_issues:
    if not mem_iss_component:
      raise ValueError("If you have memory issues, you have to preselect mem_iss_component")
    pca = IncrementalPCA(mem_iss_component)
  else:
    if variance_or_components>1:
      pca = PCA(n_components=variance_or_components) 
    else: # automted selection based on variance
      pca = PCA(n_components=variance_or_components,svd_solver="full") 
  X_pca = pca.fit_transform(df.drop(drop_cols,axis=1))
  df = pd.concat((df[drop_cols],pd.DataFrame(X_pca, columns=["PCA_"+str(i+1) for i in range(X_pca.shape[1])])),axis=1)
  return df

df_out = pv.pca_feature(df,variance_or_components=0.80,drop_cols=["target","a"]); df_out

df = df_test.copy(); df

def multiple_lags(df, start=1, end=3,columns=None):
  if not columns:
    columns = df.columns.to_list()
  lags = range(start, end+1)  # Just two lags for demonstration.

  df = df.assign(**{
      '{}_t_{}'.format(col, t): df[col].shift(t)
      for t in lags
      for col in columns
  })
  return df

df_out = pv.multiple_lags(df, start=1, end=2,columns=["a","target"]); df_out

df = df_test.copy(); df

def multiple_rolling(df, windows = [1,2], functions=["mean","std"], columns=None):
  windows = [1+a for a in windows]
  if not columns:
    columns = df.columns.to_list()
  rolling_dfs = (df[columns].rolling(i)                                    # 1. Create window
                  .agg(functions)                                # 1. Aggregate
                  .rename({col: '{0}_{1:d}'.format(col, i)
                                for col in columns}, axis=1)  # 2. Rename columns
                for i in windows)                                # For each window
  df_out = pd.concat((df, *rolling_dfs), axis=1)
  da = df_out.iloc[:,len(df.columns):]
  da = [col[0] + "_" + col[1] for col in  da.columns.to_list()]
  df_out.columns = df.columns.to_list() + da 

  return  df_out                      # 3. Concatenate dataframes

df_out = pv.multiple_rolling(df, columns=["a"]); df_out

df = df_test.copy()
df["date_fake"] = pd.date_range(start="2019-01-03", end="2019-01-06", periods=len(df)); df

def date_features(df, date="date"):
  df[date] = pd.to_datetime(df[date])
  df[date+"_month"] = df[date].dt.month.astype(int)
  df[date+"_year"]  = df[date].dt.year.astype(int)
  df[date+"_week"]  = df[date].dt.week.astype(int)
  df[date+"_day"]   = df[date].dt.day.astype(int)
  df[date+"_dayofweek"]= df[date].dt.dayofweek.astype(int)
  df[date+"_dayofyear"]= df[date].dt.dayofyear.astype(int)
  df[date+"_hour"] = df[date].dt.hour.astype(int)
  df[date+"_int"] = pd.to_datetime(df[date]).astype(int)
  return df

df_out = date_features(df, date="date_fake"); df_out.iloc[:,:8]

df = df_test.copy()
df["latitude"] = [39, 35 , 20]
df["longitude"]=  [-77, -40 , -10 ]

from math import sin, cos, sqrt, atan2, radians
def haversine_distance(row, lon="latitude", lat="longitude"):
    c_lat,c_long = radians(52.5200), radians(13.4050)
    R = 6373.0
    long = radians(row['longitude'])
    lat = radians(row['latitude'])
    
    dlon = long - c_long
    dlat = lat - c_lat
    a = sin(dlat / 2)**2 + cos(lat) * cos(c_lat) * sin(dlon / 2)**2
    c = 2 * atan2(sqrt(a), sqrt(1 - a))
    
    return R * c

df['distance_central'] = df.apply(pv.haversine_distance,axis=1); df.iloc[:,4:]

df = df_test.copy()
df["addr"] = pd.Series([
            'Washington, D.C. 20003',
            'Brooklyn, NY 11211-1755',
            'Omaha, NE 68154' ]) ; df

regex = (r'(?P<city>[A-Za-z ]+), (?P<state>[A-Z]{2}) (?P<zip>\d{5}(?:-\d{4})?)')  

df.addr.str.replace('.', '').str.extract(regex)

df = pd.util.testing.makeMixedDataFrame()
df["C"] = df["C"] + " " + df["C"] ; df

"""convert column to UPPERCASE"""

col_name = "C"
df[col_name].str.upper()

"""count string occurence in each row"""
df[col_name].str.count(r'\d') # counts number of digits

"""count # o chars in each row"""
df[col_name].str.count('o') # counts number of digits

"""split rows"""
s = pd.Series(["this is a regular sentence", "https://docs.p.org", np.nan])
s.str.split()

"""this creates new columns with the different split values (instead of lists)"""
s.str.split(expand=True)  

"""limit the number of splits to 1, and start spliting from the rights side"""
s.str.rsplit("/", n=1, expand=True) 

df = pd.util.testing.makeMixedDataFrame()
df["C"] = df["C"] + " " + df["C"] ; df

col_name = "C"

"""check if a certain word/pattern occurs in each row"""
df[col_name].str.contains('oo')  # returns True/False for each row

"""find occurences"""
df[col_name].str.findall(r'[ABC]\d') # returns a list of the found occurences of the specified pattern for each row

"""replace Weekdays by abbrevations (e.g. Monday --> Mon)"""
df[col_name].str.replace(r'(\w+day\b)', lambda x: x.groups[0][:3]) # () in r'' creates a group with one element, which we acces with x.groups[0]

"""create dataframe from regex groups (str.extract() uses first match of the pattern only)"""
df[col_name].str.extract(r'(\d?\d):(\d\d)')
df[col_name].str.extract(r'(?P<hours>\d?\d):(?P<minutes>\d\d)')
df[col_name].str.extract(r'(?P<time>(?P<hours>\d?\d):(?P<minutes>\d\d))')

"""if you want to take into account ALL matches in a row (not only first one):"""
df[col_name].str.extractall(r'(\d?\d):(\d\d)') # this generates a multiindex with level 1 = 'match', indicating the order of the match

df[col_name].replace('\n', '', regex=True, inplace=True)

"""remove all the characters after &# (including &#) for column - col_1"""
df[col_name].replace(' &#.*', '', regex=True, inplace=True)

"""remove white space at the beginning of string"""
df[col_name] = df[col_name].str.lstrip()