Dataframe in pandas

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Basics

  • Everytime you change your df, you should get an new df df = df.set_index('Day',inplace=True)

  • df.Visitors.tolist()

  • np.array(df[['Visitors','Bounce Rate']]).tolist()

pandas IO

  • quandl - datasets

  • json, html, excel, csv, sql

  • df.rename(columns = ('before_Renmae':'after_rename')) : rename the columns

  • df = pd.read_html(url) : get all the dataframe, you need to find the target

Concatenating and Appending Dataframes

  • s = pd.Series([], index = [])

Joining and Merging Dataframes

  • merge : vs join

  • left right outer inner : inner is the default how

Handling Missing Data

  • df.dropna(how='all',inplace=True)

  • df.fillna(method='ffill',inplace=True)

  • df.fillna(value=-99999,inplace=True)