From 72af610c0e683e7af47067dc420359dc463bc4bc Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Tue, 10 May 2022 17:51:59 +0200
Subject: [PATCH 01/16] add a todo in disc function

---
 pvlib/irradiance.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index c5c3b1c095..d08ce6d8e0 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1394,7 +1394,7 @@ def disc(ghi, solar_zenith, datetime_or_doy, pressure=101325,
     --------
     dirint
     """
-
+    # TODO: this function should be vectorized
     # this is the I0 calculation from the reference
     # SSC uses solar constant = 1367.0 (checked 2018 08 15)
     I0 = get_extra_radiation(datetime_or_doy, 1370., 'spencer')

From e37c4bba8e96311cd134787f883e17281483e40a Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 12 May 2022 10:53:54 +0200
Subject: [PATCH 02/16] vectorize disc

---
 pvlib/irradiance.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index d08ce6d8e0..0ea68ba8f6 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1394,11 +1394,13 @@ def disc(ghi, solar_zenith, datetime_or_doy, pressure=101325,
     --------
     dirint
     """
-    # TODO: this function should be vectorized
     # this is the I0 calculation from the reference
     # SSC uses solar constant = 1367.0 (checked 2018 08 15)
     I0 = get_extra_radiation(datetime_or_doy, 1370., 'spencer')
 
+    # Considering the extra radiation is only time dependent, broadcast it to ghi's dimensions
+    I0 = np.broadcast_to(I0, ghi.shape).astype(np.float32)
+
     kt = clearness_index(ghi, solar_zenith, I0, min_cos_zenith=min_cos_zenith,
                          max_clearness_index=1)
 

From a3f3f8ecf590ff6216fc6bd3d0a1c92cb9ffde4d Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 12 May 2022 10:55:47 +0200
Subject: [PATCH 03/16] vectorize _delta_kt_prime_dirint

---
 pvlib/irradiance.py | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 0ea68ba8f6..fb032f2a10 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1588,20 +1588,26 @@ def _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime, times):
     Calculate delta_kt_prime (Perez eqn 2 and eqn 3), or return a default value
     for use with :py:func:`_dirint_bins`.
     """
+    shape = kt_prime.shape  # times as last dimension
     if use_delta_kt_prime:
         # Perez eqn 2
-        kt_next = kt_prime.shift(-1)
-        kt_previous = kt_prime.shift(1)
-        # replace nan with values that implement Perez Eq 3 for first and last
-        # positions. Use kt_previous and kt_next to handle series of length 1
-        kt_next.iloc[-1] = kt_previous.iloc[-1]
-        kt_previous.iloc[0] = kt_next.iloc[0]
-        delta_kt_prime = 0.5 * ((kt_prime - kt_next).abs().add(
-                                (kt_prime - kt_previous).abs(),
-                                fill_value=0))
+        kt_diffp1 = np.abs(np.diff(kt_prime, axis=-1))
+        kt_diffm1 = np.flip(np.abs(np.diff(np.flip(kt_prime, axis=-1), axis=-1)), axis=-1)
+
+        kt_next = np.empty(shape, dtype=np.float32)
+        # work only on last dimension
+        kt_next[..., :-1] = kt_diffp1
+        kt_next[..., -1] = kt_diffm1[..., -1]
+
+        kt_previous = np.empty(shape, dtype=np.float32)
+        # work only on last dimension
+        kt_previous[..., 1:] = kt_diffm1
+        kt_previous[..., 0] = kt_diffp1[..., 0]
+
+        delta_kt_prime = 0.5 * (np.abs(kt_prime - kt_next) + np.abs(kt_prime - kt_previous))
     else:
         # do not change unless also modifying _dirint_bins
-        delta_kt_prime = pd.Series(-1, index=times)
+        delta_kt_prime = np.full(shape, -1)
     return delta_kt_prime
 
 

From 273ee88d79f6492ac5d2655c967fa381bcac9eda Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 12 May 2022 10:58:30 +0200
Subject: [PATCH 04/16] put shape as function argument in
 _delte_kt_prime_dirint

---
 pvlib/irradiance.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index fb032f2a10..af5e0897f4 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1583,7 +1583,7 @@ def _dirint_from_dni_ktprime(dni, kt_prime, solar_zenith, use_delta_kt_prime,
     return dni_dirint
 
 
-def _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime, times):
+def _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime, shape):
     """
     Calculate delta_kt_prime (Perez eqn 2 and eqn 3), or return a default value
     for use with :py:func:`_dirint_bins`.

From bb510823aef9d24b91412c624403dd778f43b5e7 Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 12 May 2022 10:59:14 +0200
Subject: [PATCH 05/16] vectorize _temp_dew_dirint

---
 pvlib/irradiance.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index af5e0897f4..3738d6e051 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1588,7 +1588,6 @@ def _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime, shape):
     Calculate delta_kt_prime (Perez eqn 2 and eqn 3), or return a default value
     for use with :py:func:`_dirint_bins`.
     """
-    shape = kt_prime.shape  # times as last dimension
     if use_delta_kt_prime:
         # Perez eqn 2
         kt_diffp1 = np.abs(np.diff(kt_prime, axis=-1))
@@ -1611,17 +1610,17 @@ def _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime, shape):
     return delta_kt_prime
 
 
-def _temp_dew_dirint(temp_dew, times):
+def _temp_dew_dirint(temp_dew, shape):
     """
     Calculate precipitable water from surface dew point temp (Perez eqn 4),
     or return a default value for use with :py:func:`_dirint_bins`.
     """
     if temp_dew is not None:
         # Perez eqn 4
-        w = pd.Series(np.exp(0.07 * temp_dew - 0.075), index=times)
+        w = np.exp(0.07 * temp_dew - 0.075)
     else:
         # do not change unless also modifying _dirint_bins
-        w = pd.Series(-1, index=times)
+        w = np.full(shape, -1)
     return w
 
 

From 6632758e09ac7581f5a404d467176abb22f26cb7 Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 12 May 2022 11:12:26 +0200
Subject: [PATCH 06/16] improve docstrings

---
 pvlib/irradiance.py | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 3738d6e051..a023b98b96 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1587,6 +1587,17 @@ def _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime, shape):
     """
     Calculate delta_kt_prime (Perez eqn 2 and eqn 3), or return a default value
     for use with :py:func:`_dirint_bins`.
+
+    Parameters
+    ----------
+    kt_prime : Zenith-independent clearness index
+    use_delta_kt_prime : Boolean flag whether to use calculate the stability 
+        index or to use the default value
+    shape : Shape of the input data
+
+    Returns
+    ----------
+    delta_kt_prime : Stability index
     """
     if use_delta_kt_prime:
         # Perez eqn 2
@@ -1614,6 +1625,15 @@ def _temp_dew_dirint(temp_dew, shape):
     """
     Calculate precipitable water from surface dew point temp (Perez eqn 4),
     or return a default value for use with :py:func:`_dirint_bins`.
+
+    Parameters
+    ----------
+    temp_dew : Surface dew point temperature array
+    shape : Shape of the input data
+
+    Returns
+    ----------
+    w : Precipitable water estimated from surface dew-point temperature
     """
     if temp_dew is not None:
         # Perez eqn 4

From f941da579cb42f08dcd7e651943e35f47c5a80f6 Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 12 May 2022 11:12:53 +0200
Subject: [PATCH 07/16] vectorize _dirint_coeffs

---
 pvlib/irradiance.py | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index a023b98b96..b8831931ec 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1644,7 +1644,7 @@ def _temp_dew_dirint(temp_dew, shape):
     return w
 
 
-def _dirint_coeffs(times, kt_prime, solar_zenith, w, delta_kt_prime):
+def _dirint_coeffs(kt_prime, solar_zenith, w, delta_kt_prime):
     """
     Determine the DISC to DIRINT multiplier `dirint_coeffs`.
 
@@ -1652,7 +1652,6 @@ def _dirint_coeffs(times, kt_prime, solar_zenith, w, delta_kt_prime):
 
     Parameters
     ----------
-    times : pd.DatetimeIndex
     kt_prime : Zenith-independent clearness index
     solar_zenith : Solar zenith angle
     w : precipitable water estimated from surface dew-point temperature
@@ -1662,21 +1661,28 @@ def _dirint_coeffs(times, kt_prime, solar_zenith, w, delta_kt_prime):
     -------
     dirint_coeffs : array-like
     """
-    kt_prime_bin, zenith_bin, w_bin, delta_kt_prime_bin = \
-        _dirint_bins(times, kt_prime, solar_zenith, w, delta_kt_prime)
+    kt_prime_bin, zenith_bin, w_bin, delta_kt_prime_bin = _dirint_bins(
+        kt_prime=kt_prime,
+        solar_zenith=solar_zenith,
+        w=w,
+        delta_kt_prime=delta_kt_prime,
+    )
 
     # get the coefficients
-    coeffs = _get_dirint_coeffs()
+    coeffs = _get_dirint_coeffs().astype(np.float32)
 
     # subtract 1 to account for difference between MATLAB-style bin
     # assignment and Python-style array lookup.
-    dirint_coeffs = coeffs[kt_prime_bin-1, zenith_bin-1,
-                           delta_kt_prime_bin-1, w_bin-1]
-
-    # convert unassigned bins to nan
-    dirint_coeffs = np.where((kt_prime_bin == 0) | (zenith_bin == 0) |
-                             (w_bin == 0) | (delta_kt_prime_bin == 0),
-                             np.nan, dirint_coeffs)
+    dirint_coeffs = coeffs[kt_prime_bin - 1, zenith_bin - 1,
+                            delta_kt_prime_bin - 1, w_bin - 1]
+
+    # convert unassigned bins to 1, instead of putting nan originally
+    # whenever the dirint coeff is not known it should be preferred to fall back
+    # to disc values and therefore have a coeff of 1.
+    dirint_coeffs[
+        (kt_prime_bin == 0) | (zenith_bin == 0) | 
+        (w_bin == 0) | (delta_kt_prime_bin == 0)
+    ] = 1
     return dirint_coeffs
 
 

From e0c8d9a13a2fadf07deec49d889726c31bdc32c1 Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 12 May 2022 11:16:50 +0200
Subject: [PATCH 08/16] vectorize _dirint_bins

---
 pvlib/irradiance.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index b8831931ec..440d59e3ba 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1686,13 +1686,12 @@ def _dirint_coeffs(kt_prime, solar_zenith, w, delta_kt_prime):
     return dirint_coeffs
 
 
-def _dirint_bins(times, kt_prime, zenith, w, delta_kt_prime):
+def _dirint_bins(kt_prime, zenith, w, delta_kt_prime):
     """
     Determine the bins for the DIRINT coefficients.
 
     Parameters
     ----------
-    times : pd.DatetimeIndex
     kt_prime : Zenith-independent clearness index
     zenith : Solar zenith angle
     w : precipitable water estimated from surface dew-point temperature
@@ -1702,11 +1701,12 @@ def _dirint_bins(times, kt_prime, zenith, w, delta_kt_prime):
     -------
     tuple of kt_prime_bin, zenith_bin, w_bin, delta_kt_prime_bin
     """
+    shape = kt_prime.shape
     # @wholmgren: the following bin assignments use MATLAB's 1-indexing.
     # Later, we'll subtract 1 to conform to Python's 0-indexing.
 
     # Create kt_prime bins
-    kt_prime_bin = pd.Series(0, index=times, dtype=np.int64)
+    kt_prime_bin = np.zeros(shape, dtype=np.int8)
     kt_prime_bin[(kt_prime >= 0) & (kt_prime < 0.24)] = 1
     kt_prime_bin[(kt_prime >= 0.24) & (kt_prime < 0.4)] = 2
     kt_prime_bin[(kt_prime >= 0.4) & (kt_prime < 0.56)] = 3
@@ -1715,7 +1715,7 @@ def _dirint_bins(times, kt_prime, zenith, w, delta_kt_prime):
     kt_prime_bin[(kt_prime >= 0.8) & (kt_prime <= 1)] = 6
 
     # Create zenith angle bins
-    zenith_bin = pd.Series(0, index=times, dtype=np.int64)
+    zenith_bin = np.zeros(shape, dtype=np.int8)
     zenith_bin[(zenith >= 0) & (zenith < 25)] = 1
     zenith_bin[(zenith >= 25) & (zenith < 40)] = 2
     zenith_bin[(zenith >= 40) & (zenith < 55)] = 3
@@ -1724,7 +1724,7 @@ def _dirint_bins(times, kt_prime, zenith, w, delta_kt_prime):
     zenith_bin[(zenith >= 80)] = 6
 
     # Create the bins for w based on dew point temperature
-    w_bin = pd.Series(0, index=times, dtype=np.int64)
+    w_bin = np.zeros(shape, dtype=np.int8)
     w_bin[(w >= 0) & (w < 1)] = 1
     w_bin[(w >= 1) & (w < 2)] = 2
     w_bin[(w >= 2) & (w < 3)] = 3
@@ -1732,7 +1732,7 @@ def _dirint_bins(times, kt_prime, zenith, w, delta_kt_prime):
     w_bin[(w == -1)] = 5
 
     # Create delta_kt_prime binning.
-    delta_kt_prime_bin = pd.Series(0, index=times, dtype=np.int64)
+    delta_kt_prime_bin = np.zeros(shape, dtype=np.int8)
     delta_kt_prime_bin[(delta_kt_prime >= 0) & (delta_kt_prime < 0.015)] = 1
     delta_kt_prime_bin[(delta_kt_prime >= 0.015) &
                        (delta_kt_prime < 0.035)] = 2

From 105c49f65bbd24d7829bd50cd8bb94b2e4cc299f Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 12 May 2022 11:22:11 +0200
Subject: [PATCH 09/16] vectorize dirint

---
 pvlib/irradiance.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 440d59e3ba..e77d8b72ee 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1545,7 +1545,7 @@ def dirint(ghi, solar_zenith, times, pressure=101325., use_delta_kt_prime=True,
        Global Horizontal to Direct Normal Insolation", Technical Report No.
        SERI/TR-215-3087, Golden, CO: Solar Energy Research Institute, 1987.
     """
-
+    shape = ghi.shape
     disc_out = disc(ghi, solar_zenith, times, pressure=pressure,
                     min_cos_zenith=min_cos_zenith, max_zenith=max_zenith)
     airmass = disc_out['airmass']
@@ -1554,10 +1554,10 @@ def dirint(ghi, solar_zenith, times, pressure=101325., use_delta_kt_prime=True,
     kt_prime = clearness_index_zenith_independent(
         kt, airmass, max_clearness_index=1)
     delta_kt_prime = _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime,
-                                            times)
-    w = _temp_dew_dirint(temp_dew, times)
+                                            shape)
+    w = _temp_dew_dirint(temp_dew, shape)
 
-    dirint_coeffs = _dirint_coeffs(times, kt_prime, solar_zenith, w,
+    dirint_coeffs = _dirint_coeffs(kt_prime, solar_zenith, w,
                                    delta_kt_prime)
 
     # Perez eqn 5

From 5ab066a2758f3718b7d5b55b61f047382de10caf Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 12 May 2022 11:26:06 +0200
Subject: [PATCH 10/16] avoid dividing by zero in dirindex

---
 pvlib/irradiance.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index e77d8b72ee..63ad09974a 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1833,9 +1833,13 @@ def dirindex(ghi, ghi_clearsky, dni_clearsky, zenith, times, pressure=101325.,
                                  min_cos_zenith=min_cos_zenith,
                                  max_zenith=max_zenith)
 
-    dni_dirindex = dni_clearsky * dni_dirint / dni_dirint_clearsky
+    # Avoid dividing by zero with clearsky. Whenever the dni_dirint_clearsky is zero, the array defaults
+    # to dni_dirint (which logically should be also zero)  
+    nonzero = dni_dirint_clearsky != 0
+    dni_dirindex = dni_dirint
+    dni_dirindex[nonzero] = dni_clearsky[nonzero] * dni_dirint[nonzero] / dni_dirint_clearsky[nonzero]
 
-    dni_dirindex[dni_dirindex < 0] = 0.
+    dni_dirindex[dni_dirindex < 0] = 0.0
 
     return dni_dirindex
 

From 17bee9bd8432b701c7a4223247965bf19da8dd3c Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 19 May 2022 17:25:50 +0200
Subject: [PATCH 11/16] add PVLIB_IRR_DTYPE env variable to choose precision

---
 pvlib/irradiance.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 63ad09974a..d73d3d9ff1 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -29,6 +29,7 @@
                    'fresh steel': 0.35,
                    'dirty steel': 0.08,
                    'sea': 0.06}
+PVLIB_IRR_DTYPE = getenv('PVLIB_IRR_DTYPE', default=np.float64)
 
 
 def get_extra_radiation(datetime_or_doy, solar_constant=1366.1,
@@ -1399,7 +1400,7 @@ def disc(ghi, solar_zenith, datetime_or_doy, pressure=101325,
     I0 = get_extra_radiation(datetime_or_doy, 1370., 'spencer')
 
     # Considering the extra radiation is only time dependent, broadcast it to ghi's dimensions
-    I0 = np.broadcast_to(I0, ghi.shape).astype(np.float32)
+    I0 = np.broadcast_to(I0, ghi.shape).astype(PVLIB_IRR_DTYPE)
 
     kt = clearness_index(ghi, solar_zenith, I0, min_cos_zenith=min_cos_zenith,
                          max_clearness_index=1)
@@ -1604,12 +1605,12 @@ def _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime, shape):
         kt_diffp1 = np.abs(np.diff(kt_prime, axis=-1))
         kt_diffm1 = np.flip(np.abs(np.diff(np.flip(kt_prime, axis=-1), axis=-1)), axis=-1)
 
-        kt_next = np.empty(shape, dtype=np.float32)
+        kt_next = np.empty(shape, dtype=PVLIB_IRR_DTYPE)
         # work only on last dimension
         kt_next[..., :-1] = kt_diffp1
         kt_next[..., -1] = kt_diffm1[..., -1]
 
-        kt_previous = np.empty(shape, dtype=np.float32)
+        kt_previous = np.empty(shape, dtype=PVLIB_IRR_DTYPE)
         # work only on last dimension
         kt_previous[..., 1:] = kt_diffm1
         kt_previous[..., 0] = kt_diffp1[..., 0]
@@ -1669,7 +1670,7 @@ def _dirint_coeffs(kt_prime, solar_zenith, w, delta_kt_prime):
     )
 
     # get the coefficients
-    coeffs = _get_dirint_coeffs().astype(np.float32)
+    coeffs = _get_dirint_coeffs().astype(PVLIB_IRR_DTYPE)
 
     # subtract 1 to account for difference between MATLAB-style bin
     # assignment and Python-style array lookup.

From b8631e4bd3fc3b779b1cf2fea6a1d499db669cfe Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 19 May 2022 17:29:54 +0200
Subject: [PATCH 12/16] add getenv import

---
 pvlib/irradiance.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index d73d3d9ff1..7f053c8bf4 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -7,6 +7,7 @@
 import datetime
 from collections import OrderedDict
 from functools import partial
+from os import getenv
 
 import numpy as np
 import pandas as pd

From 09c1b42ef837f524858470dc109dd6387e2a5b78 Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Thu, 19 May 2022 18:15:26 +0200
Subject: [PATCH 13/16] fix keyword argument call in _dirint_coeffs

---
 pvlib/irradiance.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 7f053c8bf4..8de22d1b7b 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1665,7 +1665,7 @@ def _dirint_coeffs(kt_prime, solar_zenith, w, delta_kt_prime):
     """
     kt_prime_bin, zenith_bin, w_bin, delta_kt_prime_bin = _dirint_bins(
         kt_prime=kt_prime,
-        solar_zenith=solar_zenith,
+        zenith=solar_zenith,
         w=w,
         delta_kt_prime=delta_kt_prime,
     )

From 201e2b0564582ae19c360dd11fa769992d02ef6d Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Fri, 20 May 2022 11:44:54 +0200
Subject: [PATCH 14/16] stickler code quality

---
 pvlib/irradiance.py | 36 +++++++++++++++++++++---------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 8de22d1b7b..6ff92604a0 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1400,7 +1400,8 @@ def disc(ghi, solar_zenith, datetime_or_doy, pressure=101325,
     # SSC uses solar constant = 1367.0 (checked 2018 08 15)
     I0 = get_extra_radiation(datetime_or_doy, 1370., 'spencer')
 
-    # Considering the extra radiation is only time dependent, broadcast it to ghi's dimensions
+    # Considering the extra radiation is only time dependent,
+    # broadcast it to ghi's dimensions
     I0 = np.broadcast_to(I0, ghi.shape).astype(PVLIB_IRR_DTYPE)
 
     kt = clearness_index(ghi, solar_zenith, I0, min_cos_zenith=min_cos_zenith,
@@ -1593,7 +1594,7 @@ def _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime, shape):
     Parameters
     ----------
     kt_prime : Zenith-independent clearness index
-    use_delta_kt_prime : Boolean flag whether to use calculate the stability 
+    use_delta_kt_prime : Boolean flag whether to use calculate the stability
         index or to use the default value
     shape : Shape of the input data
 
@@ -1604,7 +1605,9 @@ def _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime, shape):
     if use_delta_kt_prime:
         # Perez eqn 2
         kt_diffp1 = np.abs(np.diff(kt_prime, axis=-1))
-        kt_diffm1 = np.flip(np.abs(np.diff(np.flip(kt_prime, axis=-1), axis=-1)), axis=-1)
+        kt_diffm1 = np.flip(
+            np.abs(np.diff(np.flip(kt_prime, axis=-1), axis=-1)), axis=-1
+        )
 
         kt_next = np.empty(shape, dtype=PVLIB_IRR_DTYPE)
         # work only on last dimension
@@ -1616,7 +1619,9 @@ def _delta_kt_prime_dirint(kt_prime, use_delta_kt_prime, shape):
         kt_previous[..., 1:] = kt_diffm1
         kt_previous[..., 0] = kt_diffp1[..., 0]
 
-        delta_kt_prime = 0.5 * (np.abs(kt_prime - kt_next) + np.abs(kt_prime - kt_previous))
+        delta_kt_prime = 0.5 * (
+            np.abs(kt_prime - kt_next) + np.abs(kt_prime - kt_previous)
+        )
     else:
         # do not change unless also modifying _dirint_bins
         delta_kt_prime = np.full(shape, -1)
@@ -1663,12 +1668,9 @@ def _dirint_coeffs(kt_prime, solar_zenith, w, delta_kt_prime):
     -------
     dirint_coeffs : array-like
     """
-    kt_prime_bin, zenith_bin, w_bin, delta_kt_prime_bin = _dirint_bins(
-        kt_prime=kt_prime,
-        zenith=solar_zenith,
-        w=w,
-        delta_kt_prime=delta_kt_prime,
-    )
+    kt_prime_bin, zenith_bin, w_bin, delta_kt_prime_bin = \
+        _dirint_bins(kt_prime=kt_prime, zenith=solar_zenith,
+                     w=w, delta_kt_prime=delta_kt_prime)
 
     # get the coefficients
     coeffs = _get_dirint_coeffs().astype(PVLIB_IRR_DTYPE)
@@ -1679,10 +1681,11 @@ def _dirint_coeffs(kt_prime, solar_zenith, w, delta_kt_prime):
                             delta_kt_prime_bin - 1, w_bin - 1]
 
     # convert unassigned bins to 1, instead of putting nan originally
-    # whenever the dirint coeff is not known it should be preferred to fall back
+    # whenever the dirint coeff is not known
+    # it should be preferred to fall back
     # to disc values and therefore have a coeff of 1.
     dirint_coeffs[
-        (kt_prime_bin == 0) | (zenith_bin == 0) | 
+        (kt_prime_bin == 0) | (zenith_bin == 0) |
         (w_bin == 0) | (delta_kt_prime_bin == 0)
     ] = 1
     return dirint_coeffs
@@ -1835,11 +1838,14 @@ def dirindex(ghi, ghi_clearsky, dni_clearsky, zenith, times, pressure=101325.,
                                  min_cos_zenith=min_cos_zenith,
                                  max_zenith=max_zenith)
 
-    # Avoid dividing by zero with clearsky. Whenever the dni_dirint_clearsky is zero, the array defaults
-    # to dni_dirint (which logically should be also zero)  
+    # Avoid dividing by zero with clearsky.
+    # Whenever the dni_dirint_clearsky is zero, the array defaults
+    # to dni_dirint (which logically should be also zero)
     nonzero = dni_dirint_clearsky != 0
     dni_dirindex = dni_dirint
-    dni_dirindex[nonzero] = dni_clearsky[nonzero] * dni_dirint[nonzero] / dni_dirint_clearsky[nonzero]
+    dni_dirindex[nonzero] = \
+        dni_clearsky[nonzero] * dni_dirint[nonzero] / \
+        dni_dirint_clearsky[nonzero]
 
     dni_dirindex[dni_dirindex < 0] = 0.0
 

From a35746531e6f3ca85c62a75eb5173e95da30f58b Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Fri, 20 May 2022 11:46:26 +0200
Subject: [PATCH 15/16] stickler code quality #2

---
 pvlib/irradiance.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 6ff92604a0..c26d0de2c8 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1678,7 +1678,7 @@ def _dirint_coeffs(kt_prime, solar_zenith, w, delta_kt_prime):
     # subtract 1 to account for difference between MATLAB-style bin
     # assignment and Python-style array lookup.
     dirint_coeffs = coeffs[kt_prime_bin - 1, zenith_bin - 1,
-                            delta_kt_prime_bin - 1, w_bin - 1]
+                           delta_kt_prime_bin - 1, w_bin - 1]
 
     # convert unassigned bins to 1, instead of putting nan originally
     # whenever the dirint coeff is not known

From 5bf90492899551a4773b9955b2debc2c34f52bd9 Mon Sep 17 00:00:00 2001
From: Alexis Saint Georges-Chaumet <alexis.saintgeorgeschaumet@steady-sun.com>
Date: Fri, 20 May 2022 11:49:11 +0200
Subject: [PATCH 16/16] stickler

---
 pvlib/irradiance.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index c26d0de2c8..96fdedf591 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -1677,8 +1677,8 @@ def _dirint_coeffs(kt_prime, solar_zenith, w, delta_kt_prime):
 
     # subtract 1 to account for difference between MATLAB-style bin
     # assignment and Python-style array lookup.
-    dirint_coeffs = coeffs[kt_prime_bin - 1, zenith_bin - 1,
-                           delta_kt_prime_bin - 1, w_bin - 1]
+    dirint_coeffs = coeffs[kt_prime_bin-1, zenith_bin-1,
+                           delta_kt_prime_bin-1, w_bin-1]
 
     # convert unassigned bins to 1, instead of putting nan originally
     # whenever the dirint coeff is not known