DiscRates class

This class contains the discount rates for every year and discounts given values. Its attributes are:

• tag (Tag): information about the source data

• years (np.array): years

• rates (np.array): discount rates for each year (between 0 and 1)

from climada.entity import DiscRates
help(DiscRates)

2019-05-15 07:50:11,301 - climada - DEBUG - Loading default config file: /Users/aznarsig/Documents/Python/climada_python/climada/conf/defaults.conf
Help on class DiscRates in module climada.entity.disc_rates.base:

class DiscRates(builtins.object)
 |  Defines discount rates and basic methods. Loads from
 |  files with format defined in FILE_EXT.
 |
 |  Attributes:
 |      tag (Tag): information about the source data
 |      years (np.array): years
 |      rates (np.array): discount rates for each year (between 0 and 1)
 |
 |  Methods defined here:
 |
 |  __init__(self)
 |      Empty initialization.
 |
 |      Examples:
 |          Fill discount rates with values and check consistency data:
 |
 |          >>> disc_rates = DiscRates()
 |          >>> disc_rates.years = np.array([2000, 2001])
 |          >>> disc_rates.rates = np.array([0.02, 0.02])
 |          >>> disc_rates.check()
 |
 |          Read discount rates from year_2050.mat and checks consistency data.
 |
 |          >>> disc_rates = DiscRates(ENT_TEMPLATE_XLS)
 |
 |  append(self, disc_rates)
 |      Check and append discount rates to current DiscRates. Overwrite
 |      discount rate if same year.
 |
 |      Parameters:
 |          disc_rates (DiscRates): DiscRates instance to append
 |
 |      Raises:
 |          ValueError
 |
 |  check(self)
 |      Check attributes consistency.
 |
 |      Raises:
 |          ValueError
 |
 |  clear(self)
 |      Reinitialize attributes.
 |
 |  net_present_value(self, ini_year, end_year, val_years)
 |      Compute net present value between present year and future year.
 |
 |      Parameters:
 |          ini_year (float): initial year
 |          end_year (float): end year
 |          val_years (np.array): cash flow at each year btw ini_year and
 |              end_year (both included)
 |      Returns:
 |          float
 |
 |  plot(self)
 |      Plot discount rates per year.
 |
 |  read_excel(self, file_name, description='', var_names={'sheet_name': 'discount', 'col_name': {'year': 'year', 'disc': 'discount_rate'}})
 |      Read excel file following template and store variables.
 |
 |      Parameters:
 |          file_name (str): absolute file name
 |          description (str, optional): description of the data
 |          var_names (dict, optional): name of the variables in the file
 |
 |  read_mat(self, file_name, description='', var_names={'sup_field_name': 'entity', 'field_name': 'discount', 'var_name': {'year': 'year', 'disc': 'discount_rate'}})
 |      Read MATLAB file generated with previous MATLAB CLIMADA version.
 |
 |      Parameters:
 |          file_name (str): absolute file name
 |          description (str, optional): description of the data
 |          var_names (dict, optional): name of the variables in the file
 |
 |  select(self, year_range)
 |      Select discount rates in given years.
 |
 |      Parameters:
 |          year_range (np.array): continuous sequence of selected years.
 |
 |      Returns:
 |          DiscRates
 |
 |  write_excel(self, file_name, var_names={'sheet_name': 'discount', 'col_name': {'year': 'year', 'disc': 'discount_rate'}})
 |      Write excel file following template.
 |
 |      Parameters:
 |          file_name (str): absolute file name to write
 |          var_names (dict, optional): name of the variables in the file
 |
 |  ----------------------------------------------------------------------
 |  Data descriptors defined here:
 |
 |  __dict__
 |      dictionary for instance variables (if defined)
 |
 |  __weakref__
 |      list of weak references to the object (if defined)

An example of use:

%matplotlib inline
import numpy as np
from climada.entity import DiscRates

# define discount rates
disc = DiscRates()
disc.years = np.arange(1950, 2100)
disc.rates = np.ones(disc.years.size) * 0.02
disc.rates[51:55] = 0.025
disc.rates[95:120] = 0.035
disc.check()
disc.plot()

# Compute net present value between present year and future year.
ini_year = 2019
end_year = 2050
val_years = np.zeros(end_year-ini_year+1)
val_years[0] = 100000000 # initial investment
val_years[10:] = 75000 # maintenance from 10th year
npv = disc.net_present_value(ini_year, end_year, val_years)
print('net present value: {:.5e}'.format(npv))

net present value: 1.01099e+08

 Read discount rates of an Excel file

Discount rates defined in an excel file following the template provided in sheet discount of climada_python/data/system/entity_template.xlsx can be ingested directly using the method read_excel().

from climada.entity import DiscRates
from climada.util import ENT_TEMPLATE_XLS

# Fill DataFrame from Excel file
file_name = ENT_TEMPLATE_XLS # provide absolute path of the excel file
disc = DiscRates()
disc.read_excel(file_name)
print('Read file:', disc.tag.file_name)
disc.plot()

Read file: /Users/aznarsig/Documents/Python/climada_python/data/system/entity_template.xlsx

(<Figure size 288x288 with 1 Axes>,
 [<matplotlib.axes._subplots.AxesSubplot at 0x1a21d89240>])

Write discount rates

Discount rates defined in an excel file following the template provided in sheet discount of climada_python/data/system/entity_template.xlsx can be ingested directly using the method read_excel().

from climada.entity import DiscRates
from climada.util import ENT_TEMPLATE_XLS

# Fill DataFrame from Excel file
file_name = ENT_TEMPLATE_XLS # provide absolute path of the excel file
disc = DiscRates()
disc.read_excel(file_name)

# write file
disc.write_excel('results/tutorial_disc.xlsx')

Pickle can always be used as well:

from climada.util.save import save
# this generates a results folder in the current path and stores the output there
save('tutorial_disc.p', disc)

2019-05-15 07:50:15,188 - climada.util.save - INFO - Written file /Users/aznarsig/Documents/Python/climada_python/doc/tutorial/results/tutorial_disc.p