DiscRates csv support (#818)

* DiscRates: add csv support

* changelog

Author: emanuel-schmid

CHANGELOG.md

@@ -12,6 +12,8 @@ Code freeze date: YYYY-MM-DD
 
 ### Added
 
+- Read and Write methods to and from csv files for the `DiscRates` class. [#818](ttps://github.com/CLIMADA-project/climada_python/pull/818)
+
 ### Changed
 
 - Add `shapes` argument to `geo_im_from_array` to allow flexible turning on/off of plotting coastline in `plot_intensity`. [#805](https://github.com/CLIMADA-project/climada_python/pull/805)

climada/entity/disc_rates/base.py

@@ -259,9 +259,11 @@ def from_mat(cls, file_name, var_names=None):
         return cls(years=years, rates=rates)
 
     def read_mat(self, *args, **kwargs):
-        """This function is deprecated, use DiscRates.from_mats instead."""
-        LOGGER.warning("The use of DiscRates.read_mats is deprecated."
-                       "Use DiscRates.from_mats instead.")
+        """This function is deprecated, use ``DiscRates.from_mat`` instead."""
+        LOGGER.warning(
+            "The use of DiscRates.read_mat is deprecated."
+            "Use DiscRates.from_mat instead."
+        )
         self.__dict__ = DiscRates.from_mat(*args, **kwargs).__dict__
 
     @classmethod
@@ -307,8 +309,7 @@ def read_excel(self, *args, **kwargs):
         """This function is deprecated, use DiscRates.from_excel instead."""
         LOGGER.warning("The use of DiscRates.read_excel is deprecated."
                        "Use DiscRates.from_excel instead.")
-        self.__dict__ = DiscRates.from_mat(*args, **kwargs).__dict__
-
+        self.__dict__ = DiscRates.from_excel(*args, **kwargs).__dict__
 
     def write_excel(self, file_name, var_names=None):
         """
@@ -341,3 +342,68 @@ def write_excel(self, file_name, var_names=None):
             disc_ws.write(i_yr, 0, disc_yr)
             disc_ws.write(i_yr, 1, disc_rt)
         disc_wb.close()
+
+    @classmethod
+    def from_csv(
+        cls, file_name, year_column="year", disc_column="discount_rate", **kwargs
+    ):
+        """
+        Read DiscRate from a csv file following template and store variables.
+
+        Parameters
+        ----------
+        file_name: str
+            filename including path and extension
+        year_column: str, optional
+            name of the column that contains the years,
+            Default: "year"
+        disc_column: str, optional
+            name of the column that contains the discount rates,
+            Default: "discount_rate"
+        **kwargs:
+            any additional arguments, e.g., `sep`, `delimiter`, `head`,
+            are forwarded to ``pandas.read_csv``
+
+        Returns
+        -------
+        climada.entity.DiscRates :
+            The disc rates from the csv file
+        """
+        dfr = pd.read_csv(file_name, **kwargs)
+        try:
+            years = dfr[year_column].values.astype(int, copy=False)
+            rates = dfr[disc_column].values
+        except KeyError as err:
+            raise ValueError(
+                f"missing column in csv file ({year_column} or {disc_column})"
+            ) from err
+
+        return cls(years=years, rates=rates)
+
+    def write_csv(
+        self, file_name, year_column="year", disc_column="discount_rate", **kwargs
+    ):
+        """
+        Write DiscRate to a csv file following template and store variables.
+
+        Parameters
+        ----------
+        file_name: str
+            filename including path and extension
+        year_column: str, optional
+            name of the column that contains the years,
+            Default: "year"
+        disc_column: str, optional
+            name of the column that contains the discount rates,
+            Default: "discount_rate"
+        **kwargs:
+            any additional arguments, e.g., `sep`, `delimiter`, `head`,
+            are forwarded to ``pandas.read_csv``
+        """
+        dfr = pd.DataFrame(
+            {
+                year_column: self.years,
+                disc_column: self.rates,
+            }
+        )
+        dfr.to_csv(file_name, **kwargs)

climada/entity/disc_rates/test/test_base.py

@@ -21,6 +21,8 @@
 import unittest
 import numpy as np
 import copy
+from pathlib import Path
+from tempfile import TemporaryDirectory
 
 from climada import CONFIG
 from climada.entity.disc_rates.base import DiscRates
@@ -216,23 +218,46 @@ def test_demo_file_pass(self):
         self.assertEqual(disc_rate.rates.max(), 0.02)
 
 
-class TestWriter(unittest.TestCase):
-    """Test excel reader for discount rates"""
+class TestWriteRead(unittest.TestCase):
+    """Test file write read cycle for discount rates"""
+
+    @classmethod
+    def setUpClass(cls):
+        cls._td = TemporaryDirectory()
+        cls.tempdir = Path(cls._td.name)
+
+    @classmethod
+    def tearDownClass(cls):
+        cls._td.cleanup()
 
-    def test_write_read_pass(self):
+    def test_write_read_excel_pass(self):
         """Read demo excel file."""
         years = np.arange(1950, 2150)
         rates = np.ones(years.size) * 0.03
         disc_rate = DiscRates(years=years, rates=rates)
 
-        file_name = CONFIG.disc_rates.test_data.dir().joinpath('test_disc.xlsx')
+        file_name = self.tempdir.joinpath('test_disc.xlsx')
         disc_rate.write_excel(file_name)
 
         disc_read = DiscRates.from_excel(file_name)
 
         self.assertTrue(np.array_equal(disc_read.years, disc_rate.years))
         self.assertTrue(np.array_equal(disc_read.rates, disc_rate.rates))
 
+    def test_write_read_csv_pass(self):
+        """Write and read csv file."""
+        years = np.arange(1950, 2150)
+        rates = np.ones(years.size) * 0.03
+        disc_rate = DiscRates(years=years, rates=rates)
+
+        file_name = self.tempdir.joinpath('test_disc.csv')
+        disc_rate.write_csv(file_name)
+
+        disc_read = DiscRates.from_csv(file_name)
+
+        self.assertTrue(np.array_equal(disc_read.years, disc_rate.years))
+        self.assertTrue(np.array_equal(disc_read.rates, disc_rate.rates))
+
 
 # Execute Tests
 if __name__ == "__main__":
@@ -243,5 +268,5 @@ def test_write_read_pass(self):
     TESTS.addTests(unittest.TestLoader().loadTestsFromTestCase(TestNetPresValue))
     TESTS.addTests(unittest.TestLoader().loadTestsFromTestCase(TestReaderExcel))
     TESTS.addTests(unittest.TestLoader().loadTestsFromTestCase(TestReaderMat))
-    TESTS.addTests(unittest.TestLoader().loadTestsFromTestCase(TestWriter))
+    TESTS.addTests(unittest.TestLoader().loadTestsFromTestCase(TestWriteRead))
     unittest.TextTestRunner(verbosity=2).run(TESTS)