Rename variables using _

src/fixedincome/utils.py

@@ -9,13 +9,13 @@
 import scipy.optimize
 
 
-def npv(rate : float, values : np.ndarray) -> float:
+def npv(rate_ : float, values : np.ndarray) -> float:
     """
     Calculates the Net Present Value (NPV) of a series of cash flows.
 
     Parameters
     ----------
-    rate : float
+    rate_ : float
         The (simple) discount rate over the length of one period.
     values : np.ndarray
         Correspond to payments and income per period, in order.
@@ -26,7 +26,7 @@ def npv(rate : float, values : np.ndarray) -> float:
         The NPV of the given series of cash flows, discounted at the given rate.
     """
 
-    weights = np.fromfunction(function=lambda i: 1/(1 + rate)**(i + 1), shape=(values.size,), dtype=int)
+    weights = np.fromfunction(function=lambda i: 1/(1 + rate_)**(i + 1), shape=(values.size,), dtype=int)
     return np.dot(values, weights)
 
 
@@ -50,7 +50,7 @@ def irr(values: np.ndarray, guess : float = 0.1) -> float:
     return scipy.optimize.newton(func=npv, x0=guess, args=(values,), tol=0.0000001, maxiter=20)
 
 
-def rate(nper : int, pmt : float, pv : float, fv : float = 0, guess : float = 0.1) -> float:
+def rate(nper : int, pmt : float, pv_ : float, fv_ : float = 0, guess : float = 0.1) -> float:
     """
     Calculates the interest rate per period of an annuity.
 
@@ -60,9 +60,9 @@ def rate(nper : int, pmt : float, pv : float, fv : float = 0, guess : float = 0.
         The total number of payment periods in an annuity.
     pmt : float
         The constant payment amount made each period.
-    pv : float
+    pv_ : float
         The present value (i.e., total amount that a series of payments is worth now) of the annuity.
-    fv : float [optional]
+    fv_ : float [optional]
         The future value (i.e., cash balance to be attained after the last payment is made) of the annuity.
     guess : float [optional]
         An initial guess for the interest rate.
@@ -73,27 +73,27 @@ def rate(nper : int, pmt : float, pv : float, fv : float = 0, guess : float = 0.
         The interest rate per period of the annuity.
     """
 
-    cash_flows = np.array([pv] + [pmt] * nper, dtype=float)
-    cash_flows[-1] += fv
+    cash_flows = np.array([pv_] + [pmt] * nper, dtype=float)
+    cash_flows[-1] += fv_
 
     return irr(values=cash_flows, guess=guess)
 
 
-def pv(rate : float, nper : int, pmt : float, fv : float = 0, payment_type : int = 0) -> float:
+def pv(rate_ : float, nper : int, pmt : float, fv_ : float = 0, type_ : int = 0) -> float:
     """
     Calculates the present value of a loan based on a constant interest rate.
 
     Parameters
     ----------
-    rate : float
+    rate_ : float
         The interest rate per period.
     nper : int
         The total number of payment periods in an annuity.
     pmt : float
         The constant payment amount made each period.
-    fv : float [optional]
+    fv_ : float [optional]
         The future value (i.e., cash balance to be attained after the last payment is made) of the annuity.
-    payment_type : int [optional]
+    type_ : int [optional]
         Indicates when payments are due.
             - 0 [default] : at the end of the period.
             - 1 : at the beginning of the period
@@ -105,28 +105,28 @@ def pv(rate : float, nper : int, pmt : float, fv : float = 0, payment_type : int
     """
 
     if rate != 0:
-        pv = -(pmt*(1 + rate*payment_type)*(((1 + rate)**nper - 1)/rate) + fv)/((1 + rate)**nper)
+        _pv = -(pmt*(1 + rate_*type_)*(((1 + rate_)**nper - 1)/rate_) + fv_)/((1 + rate_)**nper)
     else:
-        pv = -(pmt*nper + fv)
+        _pv = -(pmt*nper + fv_)
 
-    return pv
+    return _pv
 
 
-def fv(rate : float, nper : int, pmt : float, pv : float = 0, payment_type : int = 0) -> float:
+def fv(rate_ : float, nper : int, pmt : float, pv_ : float = 0, type_ : int = 0) -> float:
     """
     Calculates the future value of a loan based on a constant interest rate.
 
     Parameters
     ----------
-    rate : float
+    rate_ : float
         The interest rate per period.
     nper : int
         The total number of payment periods in an annuity.
     pmt : float
         The constant payment amount made each period.
-    pv : float [optional]
+    pv_ : float [optional]
         The present value of the annuity.
-    payment_type : int [optional]
+    type_ : int [optional]
         Indicates when payments are due.
             - 0 [default] : at the end of the period.
             - 1 : at the beginning of the period
@@ -138,8 +138,8 @@ def fv(rate : float, nper : int, pmt : float, pv : float = 0, payment_type : int
     """
 
     if rate != 0:
-        fv = -(pv*(1 + rate)**nper + pmt*(1 + rate*payment_type)*(((1 + rate)**nper - 1)/rate))
+        _fv = -(pv_*(1 + rate_)**nper + pmt*(1 + rate_*type_)*(((1 + rate_)**nper - 1)/rate_))
     else:
-        fv = -(pmt*nper + pv)
+        _fv = -(pmt*nper + pv_)
 
-    return fv
+    return _fv