[ENH] Add cummin() and cummax() functions for cumulative min/max calculation

docs/api/index-api.rst

@@ -165,6 +165,8 @@ Functions
       - Count the number of NA values per column
     * - :func:`cummax()`
       - Calculate the cumulative maximum of values per column
+    * - :func:`cummin()`
+      - Calculate the cumulative minimum of values per column
     * - :func:`cumsum()`
       - Calculate the cumulative sum of values per column
     * - :func:`cov()`
@@ -236,8 +238,8 @@ Other
     count()           <dt/count>
     countna()         <dt/countna>
     cov()             <dt/cov>
-    cummin()          <dt/cummin>
     cummax()          <dt/cummax>
+    cummin()          <dt/cummin>
     cumsum()          <dt/cumsum>
     cut()             <dt/cut>
     dt                <dt/dt>

docs/releases/v1.1.0.rst

@@ -101,9 +101,6 @@
     -[fix] Reducers and row-wise functions now support :attr:`void <dt.Type.void>`
        columns. [#3284]
 
-    -[fix] All the row-wise functions now support :attr:`void <dt.Type.void>`
-       columns. [#3284]
-
 
     fread
     -----

src/core/documentation.h

@@ -30,8 +30,8 @@ extern const char* doc_dt_corr;
 extern const char* doc_dt_count;
 extern const char* doc_dt_countna;
 extern const char* doc_dt_cov;
-extern const char* doc_dt_cummin;
 extern const char* doc_dt_cummax;
+extern const char* doc_dt_cummin;
 extern const char* doc_dt_cumsum;
 extern const char* doc_dt_cut;
 extern const char* doc_dt_first;
@@ -281,8 +281,8 @@ extern const char* doc_FExpr;
 extern const char* doc_FExpr_as_type;
 extern const char* doc_FExpr_count;
 extern const char* doc_FExpr_countna;
-extern const char* doc_FExpr_cummin;
 extern const char* doc_FExpr_cummax;
+extern const char* doc_FExpr_cummin;
 extern const char* doc_FExpr_cumsum;
 extern const char* doc_FExpr_extend;
 extern const char* doc_FExpr_first;

src/core/expr/fexpr.cc

@@ -295,26 +295,88 @@ DECLARE_METHOD(&PyFExpr::re_match)
 // Miscellaneous
 //------------------------------------------------------------------------------
 
-oobj PyFExpr::sum(const XArgs&) {
-  auto sumFn = oobj::import("datatable", "sum");
-  return sumFn.call({this});
+
+oobj PyFExpr::as_type(const XArgs& args) {
+  auto as_typeFn = oobj::import("datatable", "as_type");
+  oobj new_type = args[0].to_oobj();
+  return as_typeFn.call({this, new_type});
 }
 
-DECLARE_METHOD(&PyFExpr::sum)
-    ->name("sum")
-    ->docs(dt::doc_FExpr_sum);
+DECLARE_METHOD(&PyFExpr::as_type)
+    ->name("as_type")
+    ->docs(dt::doc_FExpr_as_type)
+    ->arg_names({"new_type"})
+    ->n_positional_args(1)
+    ->n_required_args(1);
 
 
-oobj PyFExpr::prod(const XArgs&) {
-  auto prodFn = oobj::import("datatable", "prod");
-  return prodFn.call({this});
+oobj PyFExpr::count(const XArgs&) {
+  auto countFn = oobj::import("datatable", "count");
+  return countFn.call({this});
 }
 
-DECLARE_METHOD(&PyFExpr::prod)
-    ->name("prod")
-    ->docs(dt::doc_FExpr_prod);
+DECLARE_METHOD(&PyFExpr::count)
+    ->name("count")
+    ->docs(dt::doc_FExpr_count);
+
+
+oobj PyFExpr::countna(const XArgs&) {
+  auto countnaFn = oobj::import("datatable", "countna");
+  return countnaFn.call({this});
+}
+
+DECLARE_METHOD(&PyFExpr::countna)
+    ->name("countna")
+    ->docs(dt::doc_FExpr_countna);
+
+oobj PyFExpr::cummax(const XArgs&) {
+  auto cummaxFn = oobj::import("datatable", "cummax");
+  return cummaxFn.call({this});
+}
+
+DECLARE_METHOD(&PyFExpr::cummax)
+    ->name("cummax")
+    ->docs(dt::doc_FExpr_cummax);
+
+oobj PyFExpr::cummin(const XArgs&) {
+  auto cumminFn = oobj::import("datatable", "cummin");
+  return cumminFn.call({this});
+}
+
+DECLARE_METHOD(&PyFExpr::cummin)
+    ->name("cummin")
+    ->docs(dt::doc_FExpr_cummin);
+
+
+oobj PyFExpr::cumsum(const XArgs&) {
+  auto cumsumFn = oobj::import("datatable", "cumsum");
+  return cumsumFn.call({this});
+}
+
+DECLARE_METHOD(&PyFExpr::cumsum)
+    ->name("cumsum")
+    ->docs(dt::doc_FExpr_cumsum);
+
+
+oobj PyFExpr::first(const XArgs&) {
+  auto firstFn = oobj::import("datatable", "first");
+  return firstFn.call({this});
+}
+
+DECLARE_METHOD(&PyFExpr::first)
+    ->name("first")
+    ->docs(dt::doc_FExpr_first);
 
 
+oobj PyFExpr::last(const XArgs&) {
+  auto lastFn = oobj::import("datatable", "last");
+  return lastFn.call({this});
+}
+
+DECLARE_METHOD(&PyFExpr::last)
+    ->name("last")
+    ->docs(dt::doc_FExpr_last);
+
 oobj PyFExpr::max(const XArgs&) {
   auto maxFn = oobj::import("datatable", "max");
   return maxFn.call({this});
@@ -358,6 +420,25 @@ DECLARE_METHOD(&PyFExpr::min)
     ->docs(dt::doc_FExpr_min);
 
 
+oobj PyFExpr::nunique(const XArgs&) {
+  auto nuniqueFn = oobj::import("datatable", "nunique");
+  return nuniqueFn.call({this});
+}
+
+DECLARE_METHOD(&PyFExpr::nunique)
+    ->name("nunique")
+    ->docs(dt::doc_FExpr_nunique);
+
+oobj PyFExpr::prod(const XArgs&) {
+  auto prodFn = oobj::import("datatable", "prod");
+  return prodFn.call({this});
+}
+
+DECLARE_METHOD(&PyFExpr::prod)
+    ->name("prod")
+    ->docs(dt::doc_FExpr_prod);
+
+
 
 oobj PyFExpr::rowall(const XArgs&) {
   auto rowallFn = oobj::import("datatable", "rowall");
@@ -379,6 +460,23 @@ DECLARE_METHOD(&PyFExpr::rowany)
     ->name("rowany")
     ->docs(dt::doc_FExpr_rowany);
 
+oobj PyFExpr::rowargmax(const XArgs&) {
+  auto rowargmaxFn = oobj::import("datatable", "rowargmax");
+  return rowargmaxFn.call({this});
+}
+
+DECLARE_METHOD(&PyFExpr::rowargmax)
+    ->name("rowargmax")
+    ->docs(dt::doc_FExpr_rowargmax);
+
+oobj PyFExpr::rowargmin(const XArgs&) {
+  auto rowargminFn = oobj::import("datatable", "rowargmin");
+  return rowargminFn.call({this});
+}
+
+DECLARE_METHOD(&PyFExpr::rowargmin)
+    ->name("rowargmin")
+    ->docs(dt::doc_FExpr_rowargmin);
 
 
 oobj PyFExpr::rowcount(const XArgs&) {
@@ -413,14 +511,6 @@ DECLARE_METHOD(&PyFExpr::rowlast)
     ->docs(dt::doc_FExpr_rowlast);
 
 
-oobj PyFExpr::rowargmax(const XArgs&) {
-  auto rowargmaxFn = oobj::import("datatable", "rowargmax");
-  return rowargmaxFn.call({this});
-}
-
-DECLARE_METHOD(&PyFExpr::rowargmax)
-    ->name("rowargmax")
-    ->docs(dt::doc_FExpr_rowargmax);
 
 
 oobj PyFExpr::rowmax(const XArgs&) {
@@ -444,15 +534,6 @@ DECLARE_METHOD(&PyFExpr::rowmean)
     ->docs(dt::doc_FExpr_rowmean);
 
 
-oobj PyFExpr::rowargmin(const XArgs&) {
-  auto rowargminFn = oobj::import("datatable", "rowargmin");
-  return rowargminFn.call({this});
-}
-
-DECLARE_METHOD(&PyFExpr::rowargmin)
-    ->name("rowargmin")
-    ->docs(dt::doc_FExpr_rowargmin);
-
 
 oobj PyFExpr::rowmin(const XArgs&) {
   auto rowminFn = oobj::import("datatable", "rowmin");
@@ -464,7 +545,6 @@ DECLARE_METHOD(&PyFExpr::rowmin)
     ->docs(dt::doc_FExpr_rowmin);
 
 
-
 oobj PyFExpr::rowsd(const XArgs&) {
   auto rowsdFn = oobj::import("datatable", "rowsd");
   return rowsdFn.call({this});
@@ -486,7 +566,6 @@ DECLARE_METHOD(&PyFExpr::rowsum)
     ->docs(dt::doc_FExpr_rowsum);
 
 
-
 oobj PyFExpr::sd(const XArgs&) {
   auto sdFn = oobj::import("datatable", "sd");
   return sdFn.call({this});
@@ -497,7 +576,6 @@ DECLARE_METHOD(&PyFExpr::sd)
     ->docs(dt::doc_FExpr_sd);
 
 
-
 oobj PyFExpr::shift(const XArgs& args) {
   auto shiftFn = oobj::import("datatable", "shift");
   oobj n = args[0]? args[0].to_oobj() : py::oint(1);
@@ -510,103 +588,16 @@ DECLARE_METHOD(&PyFExpr::shift)
     ->arg_names({"n"})
     ->n_positional_or_keyword_args(1);
 
-
-
-oobj PyFExpr::last(const XArgs&) {
-  auto lastFn = oobj::import("datatable", "last");
-  return lastFn.call({this});
-}
-
-DECLARE_METHOD(&PyFExpr::last)
-    ->name("last")
-    ->docs(dt::doc_FExpr_last);
-
-
-
-oobj PyFExpr::count(const XArgs&) {
-  auto countFn = oobj::import("datatable", "count");
-  return countFn.call({this});
-}
-
-DECLARE_METHOD(&PyFExpr::count)
-    ->name("count")
-    ->docs(dt::doc_FExpr_count);
-
-
-
-oobj PyFExpr::first(const XArgs&) {
-  auto firstFn = oobj::import("datatable", "first");
-  return firstFn.call({this});
-}
-
-DECLARE_METHOD(&PyFExpr::first)
-    ->name("first")
-    ->docs(dt::doc_FExpr_first);
-
-
-oobj PyFExpr::as_type(const XArgs& args) {
-  auto as_typeFn = oobj::import("datatable", "as_type");
-  oobj new_type = args[0].to_oobj();
-  return as_typeFn.call({this, new_type});
-}
-
-
-DECLARE_METHOD(&PyFExpr::as_type)
-    ->name("as_type")
-    ->docs(dt::doc_FExpr_as_type)
-    ->arg_names({"new_type"})
-    ->n_positional_args(1)
-    ->n_required_args(1);
-
-
-oobj PyFExpr::nunique(const XArgs&) {
-  auto nuniqueFn = oobj::import("datatable", "nunique");
-  return nuniqueFn.call({this});
-}
-
-DECLARE_METHOD(&PyFExpr::nunique)
-    ->name("nunique")
-    ->docs(dt::doc_FExpr_nunique);
-
-
-oobj PyFExpr::countna(const XArgs&) {
-  auto countnaFn = oobj::import("datatable", "countna");
-  return countnaFn.call({this});
-}
-
-DECLARE_METHOD(&PyFExpr::countna)
-    ->name("countna")
-    ->docs(dt::doc_FExpr_countna);
-
-
-oobj PyFExpr::cumsum(const XArgs&) {
-  auto cumsumFn = oobj::import("datatable", "cumsum");
-  return cumsumFn.call({this});
-}
-
-DECLARE_METHOD(&PyFExpr::cumsum)
-    ->name("cumsum")
-    ->docs(dt::doc_FExpr_cumsum);
-
-
-oobj PyFExpr::cummin(const XArgs&) {
-  auto cumminFn = oobj::import("datatable", "cummin");
-  return cumminFn.call({this});
+oobj PyFExpr::sum(const XArgs&) {
+  auto sumFn = oobj::import("datatable", "sum");
+  return sumFn.call({this});
 }
 
-DECLARE_METHOD(&PyFExpr::cummin)
-    ->name("cummin")
-    ->docs(dt::doc_FExpr_cummin);
+DECLARE_METHOD(&PyFExpr::sum)
+    ->name("sum")
+    ->docs(dt::doc_FExpr_sum);
 
 
-oobj PyFExpr::cummax(const XArgs&) {
-  auto cummaxFn = oobj::import("datatable", "cummax");
-  return cummaxFn.call({this});
-}
-
-DECLARE_METHOD(&PyFExpr::cummax)
-    ->name("cummax")
-    ->docs(dt::doc_FExpr_cummax);
 
 //------------------------------------------------------------------------------
 // Class decoration

src/datatable/__init__.py

@@ -27,8 +27,8 @@
     as_type,
     by,
     cbind,
-    cummin,
     cummax,
+    cummin,
     cumsum,
     cut,
     fread,
@@ -87,8 +87,8 @@
     "corr",
     "count",
     "cov",
-    "cummin",
     "cummax",
+    "cummin",
     "cumsum",
     "cut",
     "dt",

tests/test-f.py

@@ -455,4 +455,5 @@ def test_cummin():
     assert str(dt.cummin(f.A)) == str(f.A.cummin())
     assert str(dt.cummin(f[:])) == str(f[:].cummin())
     DT = dt.Frame(A = [9, 8, 2, 3, None, None, 3, 0, 5, 5, 8, None, 1])
-    assert_equals(DT[:, f.A.cummin()], DT[:, dt.cummin(f.A)])
+    assert_equals(DT[:, f.A.cummin()], DT[:, dt.cummin(f.A)])
+