mlr step -a from-first

c/mapping/mapper_step.c

@@ -68,6 +68,7 @@ static void      mapper_step_free(void* pvstate);
 static sllv_t*   mapper_step_process(lrec_t* pinrec, context_t* pctx, void* pvstate);
 
 static step_t* step_delta_alloc(char* input_field_name, int allow_int_float);
+static step_t* step_from_first_alloc(char* input_field_name, int allow_int_float);
 static step_t* step_ratio_alloc(char* input_field_name, int allow_int_float);
 static step_t* step_rsum_alloc(char* input_field_name, int allow_int_float);
 static step_t* step_counter_alloc(char* input_field_name, int allow_int_float);
@@ -80,10 +81,11 @@ typedef struct _step_lookup_t {
 	char* desc;
 } step_lookup_t;
 static step_lookup_t step_lookup_table[] = {
-	{"delta",   step_delta_alloc,   "Compute differences in field(s) between successive records"},
-	{"ratio",   step_ratio_alloc,   "Compute ratios in field(s) between successive records"},
-	{"rsum",    step_rsum_alloc,    "Compute running sums of field(s) between successive records"},
-	{"counter", step_counter_alloc, "Count instances of field(s) between successive records"},
+	{"delta",      step_delta_alloc,      "Compute differences in field(s) between successive records"},
+	{"from-first", step_from_first_alloc, "Compute differences in field(s) from first record"},
+	{"ratio",      step_ratio_alloc,      "Compute ratios in field(s) between successive records"},
+	{"rsum",       step_rsum_alloc,       "Compute running sums of field(s) between successive records"},
+	{"counter",    step_counter_alloc,    "Count instances of field(s) between successive records"},
 };
 static int step_lookup_table_length = sizeof(step_lookup_table) / sizeof(step_lookup_table[0]);
 
@@ -287,6 +289,36 @@ static step_t* step_delta_alloc(char* input_field_name, int allow_int_float) {
 }
 // xxx step_delta_free et al.
 
+// ----------------------------------------------------------------
+typedef struct _step_from_first_state_t {
+	mv_t  first;
+	char* output_field_name;
+	int   allow_int_float;
+} step_from_first_state_t;
+static void step_from_first_nprocess(void* pvstate, mv_t* pnumv, lrec_t* prec) {
+	step_from_first_state_t* pstate = pvstate;
+	mv_t from_first;
+	if (mv_is_null(&pstate->first)) {
+		from_first = pstate->allow_int_float ? mv_from_int(0LL) : mv_from_float(0.0);
+		pstate->first = *pnumv;
+	} else {
+		from_first = n_nn_minus_func(pnumv, &pstate->first);
+	}
+	lrec_put(prec, pstate->output_field_name, mv_format_val(&from_first), LREC_FREE_ENTRY_VALUE);
+}
+static step_t* step_from_first_alloc(char* input_field_name, int allow_int_float) {
+	step_t* pstep = mlr_malloc_or_die(sizeof(step_t));
+	step_from_first_state_t* pstate = mlr_malloc_or_die(sizeof(step_from_first_state_t));
+	pstate->first = mv_from_null();
+	pstate->allow_int_float = allow_int_float;
+	pstate->output_field_name = mlr_paste_2_strings(input_field_name, "_from_first");
+	pstep->pvstate        = (void*)pstate;
+	pstep->pdprocess_func = NULL;
+	pstep->pnprocess_func = step_from_first_nprocess;
+	pstep->psprocess_func = NULL;
+	return pstep;
+}
+
 // ----------------------------------------------------------------
 typedef struct _step_ratio_state_t {
 	double prev;

c/reg_test/expected/out

@@ -4893,6 +4893,24 @@ a=zee,b=wye,i=8,x=0.5985540091064224,yyy=0.976181385699006,x_rsum=1.125680,x_del
 aaa=hat,bbb=wye,i=9,x=0.03144187646093577,y=0.7495507603507059
 a=pan,b=wye,i=10,x=0.5026260055412137,y=0.9526183602969864,x_rsum=0.849416,x_delta=0.155836,x_counter=2,y_rsum=1.679421,y_delta=0.225815,y_counter=2
 
+mlr --icsvlite --opprint step -a from-first -f x ./reg_test/input/from-first.csv
+x   g     x_from_first
+100 red   0
+203 red   103
+101 green 1
+307 red   207
+209 green 109
+314 green 214
+
+mlr --icsvlite --opprint step -a from-first -f x -g g ./reg_test/input/from-first.csv
+x   g     x_from_first
+100 red   0
+203 red   103
+101 green 0
+307 red   207
+209 green 108
+314 green 213
+
 mlr --opprint histogram -f x,y --lo 0 --hi 1 --nbins 20 ./reg_test/input/small
 bin_lo   bin_hi   x_count y_count
 0.000000 0.050000 1       0

c/reg_test/input/Makefile.am

@@ -21,6 +21,7 @@ EXTRA_DIST=	\
 		e.pprint \
 		f.csv \
 		f.pprint \
+		from-first.csv \
 		fsec2xhms \
 		g.csv \
 		g.pprint \

c/reg_test/input/from-first.csv

@@ -0,0 +1,7 @@
+x,g
+100,red
+203,red
+101,green
+307,red
+209,green
+314,green

c/reg_test/run

@@ -331,6 +331,9 @@ run_mlr --opprint step -a rsum,delta,counter -f x,y -g a $indir/abixy
 run_mlr --odkvp   step -a rsum,delta,counter -f x,y      $indir/abixy-het
 run_mlr --odkvp   step -a rsum,delta,counter -f x,y -g a $indir/abixy-het
 
+run_mlr --icsvlite --opprint step -a from-first -f x      $indir/from-first.csv
+run_mlr --icsvlite --opprint step -a from-first -f x -g g $indir/from-first.csv
+
 run_mlr --opprint histogram -f x,y --lo 0 --hi 1 --nbins 20 $indir/small
 
 # ----------------------------------------------------------------

c/todo.txt

@@ -8,8 +8,8 @@ TOP OF LIST
 
 ----------------------------------------------------------------
 
-! 1e6 accepted from field value but not literal. DSLs, and UTs.
-* mlr step from-first (check against delta + rsum ...)
+! scinot@literals: cut a 3.0.1
+
 * bar --auto (w/ hold & emit & left-right labels)
 
 * faqents:

doc/mlr.1.premade

@@ -2,12 +2,12 @@
 .\"     Title: mlr
 .\"    Author: [see the "AUTHOR" section]
 .\" Generator: ./mkman.rb
-.\"      Date: 2015-11-24
+.\"      Date: 2015-11-25
 .\"    Manual: \ \&
 .\"    Source: \ \&
 .\"  Language: English
 .\"
-.TH "MILLER" "1" "2015-11-24" "\ \&" "\ \&"
+.TH "MILLER" "1" "2015-11-25" "\ \&" "\ \&"
 .\" -----------------------------------------------------------------
 .\" * Portability definitions
 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -38,7 +38,7 @@ on integer-indexed fields: if the natural data structure for the latter is the
 array, then Miller's natural data structure is the insertion-ordered hash map.
 This encompasses a variety of data formats, including but not limited to the
 familiar CSV.  (Miller can handle positionally-indexed data as a special
-case.) This manpage documents Miller v3.0.0.
+case.) This manpage documents Miller v3.0.0-dev.
 .SH "EXAMPLES"
 .sp
 
@@ -753,6 +753,7 @@ Computes values dependent on the previous record, optionally grouped
 by category.
 -a {delta,rsum,...}   Names of steppers: comma-separated, one or more of:
   delta    Compute differences in field(s) between successive records
+  from-first Compute differences in field(s) from first record
   ratio    Compute ratios in field(s) between successive records
   rsum     Compute running sums of field(s) between successive records
   counter  Count instances of field(s) between successive records

doc/reference.html

@@ -432,7 +432,7 @@ Output of one verb may be chained as input to another using "then", e.g.
   mlr stats1 -a min,mean,max -f flag,u,v -g color then sort -f color
 
 For more information please see http://johnkerl.org/miller/doc and/or
-http://github.com/johnkerl/miller. This is Miller version v3.0.0.
+http://github.com/johnkerl/miller. This is Miller version v3.0.0-dev.
 </pre>
 </div>
 <p/>
@@ -2572,6 +2572,7 @@ Computes values dependent on the previous record, optionally grouped
 by category.
 -a {delta,rsum,...}   Names of steppers: comma-separated, one or more of:
   delta    Compute differences in field(s) between successive records
+  from-first Compute differences in field(s) from first record
   ratio    Compute ratios in field(s) between successive records
   rsum     Compute running sums of field(s) between successive records
   counter  Count instances of field(s) between successive records