DS – Pandas

Pandas

How to creates a dates ranges in Pandas?

How to creates a dates DataFrame in Pandas?

# dates
dates = pd.date_range('2010-04-21', '2015-04-21')

# create a data frame of dates as index column
df = pd.DataFrame(index=dates)

How to read a CSV File?

How to read CSV file with specific index columns?

How to parse dates in a CSV File?

How to read only required columns from CSV File?

How to specific the NULL values notation in CSV File?

# read csv file
df_spy = pd.read_csv(
        'data/%s.csv' %s 'SPY',
        index_col='Dates', # specific index
        parse_dates=True, # identify Date columns as DateTime values
        usecols=['Date', 'Adj Close'], # cols we need
        na_values=['nan'] # csv has NAN as NULL values, so tell CSV ahead.
            )

How to join two data frames?

# join data frames - default LEFT join
df = df1.join(df_spy)

How to rename a data frame column?

df.rename(columns={'Adj Close':'SPY'})

How to drop na values in a data frame?

df.dropna()

How to do a inner join of data frames?

df.join(df_)

How to plot a DataFrame?

How to set plot fontsize?

How to set plot label?

How to set x label and y label?

ax = df.plot(title='Stock Prices', fontsize=2)
ax.set_xlabel('Date')
ax.set_ylabel('Prices')
plt.show()

How take a slice of data?

df_new = df.ix[start_index:end_index]

Cheat Sheet

Felt too easy? Here is one more for you

• http://www.datadependence.com/2016/05/scientific-python-pandas/