From 9d2f411e047b7cd33abac46f2b892b5400e7e689 Mon Sep 17 00:00:00 2001
From: Michael Uleysky <uleysky@poi.dvo.ru>
Date: Mon, 15 Jan 2024 16:17:38 +1000
Subject: [PATCH] Added interface for partially writing a variable to a netcdf
 file

---
 include/ncfilew.h | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/include/ncfilew.h b/include/ncfilew.h
index d49198a..bcd5d59 100644
--- a/include/ncfilew.h
+++ b/include/ncfilew.h
@@ -23,26 +23,31 @@ class NCFileWBase
  {
   static constexpr nc_type nc = NC_UBYTE;
   static int               put_var(int nc, int vid, const michlib::uint1* data) { return nc_put_var_ubyte(nc, vid, data); }
+  static int put_vara(int nc, int vid, const size_t* startp, const size_t* countp, const michlib::uint1* data) { return nc_put_vara_ubyte(nc, vid, startp, countp, data); }
  };
  template<class Dummy> struct NCTypeD<michlib::int2, Dummy>
  {
   static constexpr nc_type nc = NC_SHORT;
   static int               put_var(int nc, int vid, const michlib::int2* data) { return nc_put_var_short(nc, vid, data); }
+  static int put_vara(int nc, int vid, const size_t* startp, const size_t* countp, const michlib::int2* data) { return nc_put_vara_short(nc, vid, startp, countp, data); }
  };
  template<class Dummy> struct NCTypeD<michlib::uint2, Dummy>
  {
   static constexpr nc_type nc = NC_USHORT;
   static int               put_var(int nc, int vid, const michlib::uint2* data) { return nc_put_var_ushort(nc, vid, data); }
+  static int put_vara(int nc, int vid, const size_t* startp, const size_t* countp, const michlib::uint2* data) { return nc_put_vara_ushort(nc, vid, startp, countp, data); }
  };
  template<class Dummy> struct NCTypeD<michlib::int4, Dummy>
  {
   static constexpr nc_type nc = NC_INT;
   static int               put_var(int nc, int vid, const michlib::int4* data) { return nc_put_var_int(nc, vid, data); }
+  static int put_vara(int nc, int vid, const size_t* startp, const size_t* countp, const michlib::int4* data) { return nc_put_vara_int(nc, vid, startp, countp, data); }
  };
  template<class Dummy> struct NCTypeD<michlib::uint4, Dummy>
  {
   static constexpr nc_type nc = NC_UINT;
   static int               put_var(int nc, int vid, const michlib::uint4* data) { return nc_put_var_uint(nc, vid, data); }
+  static int put_vara(int nc, int vid, const size_t* startp, const size_t* countp, const michlib::uint4* data) { return nc_put_vara_uint(nc, vid, startp, countp, data); }
  };
  template<class Dummy> struct NCTypeD<michlib::int8, Dummy>
  {
@@ -56,11 +61,13 @@ class NCFileWBase
  {
   static constexpr nc_type nc = NC_FLOAT;
   static int               put_var(int nc, int vid, const float* data) { return nc_put_var_float(nc, vid, data); }
+  static int               put_vara(int nc, int vid, const size_t* startp, const size_t* countp, const float* data) { return nc_put_vara_float(nc, vid, startp, countp, data); }
  };
  template<class Dummy> struct NCTypeD<double, Dummy>
  {
   static constexpr nc_type nc = NC_DOUBLE;
   static int               put_var(int nc, int vid, const double* data) { return nc_put_var_double(nc, vid, data); }
+  static int               put_vara(int nc, int vid, const size_t* startp, const size_t* countp, const double* data) { return nc_put_vara_double(nc, vid, startp, countp, data); }
  };
  template<class Dummy> struct NCTypeD<MString, Dummy>
  {
@@ -287,6 +294,40 @@ class NCFileWBase
   err.Reset(NCTypeD<T, void>::put_var(ncid, varid, data));
  }
 
+ template<class T>
+ requires requires(int nc, int vid, const size_t* start, const size_t* count, const T* d) {
+  {
+   NCTypeD<T, void>::put_vara(nc, vid, start, count, d)
+  } -> std::same_as<int>;
+ }
+ void WriteVar(const MString& vname, size_t ind, const T* data)
+ {
+  if(err.IsErr()) return;
+
+  int varid;
+  err.Reset(nc_inq_varid(ncid, vname.Buf(), &varid));
+  if(err.IsErr()) return;
+
+  int ndim;
+  err.Reset(nc_inq_var(ncid, varid, nullptr, nullptr, &ndim, nullptr, nullptr));
+  if(err.IsErr()) return;
+  std::vector<int> dimids(ndim);
+  err.Reset(nc_inq_var(ncid, varid, nullptr, nullptr, nullptr, dimids.data(), nullptr));
+  if(err.IsErr()) return;
+
+  std::vector<size_t> start(ndim), count(ndim);
+  start[0] = ind;
+  count[0] = 1;
+  for(size_t i = 1; i < dimids.size(); i++)
+  {
+   start[i] = 0;
+   err.Reset(nc_inq_dim(ncid, dimids[i], nullptr, &count[i]));
+   if(err.IsErr()) return;
+  }
+
+  err.Reset(NCTypeD<T, void>::put_vara(ncid, varid, start.data(), count.data(), data));
+ }
+
  private:
  // Members
  int   ncid;