probe: Rework the PROBE_ACCURACY command parameters

Don't default to a Z location of 10, as that could cause damage if the
probe's z_offset is greater than 10.  Instead, use the "retract
distance" method that is used for normal multi-sample probing.

Update the PROBE_ACCURACY command parameter names to use the same
parameter names as the PROBE command.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

3 files changed, 28 insertions, 28 deletions

diff --git a/docs/Config_Changes.md b/docs/Config_Changes.md
index 40060205..6ba35289 100644
--- a/docs/Config_Changes.md
+++ b/docs/Config_Changes.md
@@ -6,6 +6,10 @@ All dates in this document are approximate.
 
 # Changes
 
+20190710: The optional parameters of the PROBE_ACCURACY command have
+changed. It may be necessary to update any macros or scripts that use
+that command.
+
 20190628: All configuration options have been removed from the
 [skew_correction] section.  Configuration for skew_correction
 is now done via the SET_SKEW gcode.  See skew_correction.md
diff --git a/docs/G-Codes.md b/docs/G-Codes.md
index f38c1a28..b995fa1c 100644
--- a/docs/G-Codes.md
+++ b/docs/G-Codes.md
@@ -231,10 +231,12 @@ enabled:
   for details).
 - `QUERY_PROBE`: Report the current status of the probe ("triggered"
   or "open").
-- `PROBE_ACCURACY [REPEAT=<times>] [SPEED=<speed mm/s>] [X=<x pos>]
-  [Y=<y pos>] [Z=<z height>]`: Calculate the maximum, minimum, average,
-  median and standard deviation. The default values are: REPEAT=10,
-  SPEED=probe config speed, X=current X, Y=current Y and Z=10.
+- `PROBE_ACCURACY [PROBE_SPEED=<mm/s>] [SAMPLES=<count>]
+  [SAMPLE_RETRACT_DIST=<mm>]`: Calculate the maximum, minimum,
+  average, median, and standard deviation of multiple probe
+  samples. By default, 10 SAMPLES are taken. Otherwise the optional
+  parameters default to their equivalent setting in the probe config
+  section.
 - `PROBE_CALIBRATE [SPEED=<speed>] [<probe_parameter>=<value>]`: Run a
   helper script useful for calibrating the probe's z_offset. See the
   PROBE command for details on the optional probe parameters. See the
diff --git a/klippy/extras/probe.py b/klippy/extras/probe.py
index a6c71428..a13d4098 100644
--- a/klippy/extras/probe.py
+++ b/klippy/extras/probe.py
@@ -150,32 +150,26 @@ class PrinterProbe:
             "probe: %s" % (["open", "TRIGGERED"][not not res],))
     cmd_PROBE_ACCURACY_help = "Probe Z-height accuracy at current XY position"
     def cmd_PROBE_ACCURACY(self, params):
+        speed = self.gcode.get_float(
+            "PROBE_SPEED", params, self.speed, above=0.)
+        sample_count = self.gcode.get_int("SAMPLES", params, 10, minval=1)
+        sample_retract_dist = self.gcode.get_float(
+            "SAMPLE_RETRACT_DIST", params, self.sample_retract_dist, above=0.)
         toolhead = self.printer.lookup_object('toolhead')
         pos = toolhead.get_position()
-        number_of_reads = self.gcode.get_int('REPEAT', params, default=10,
-                                                       minval=4, maxval=50)
-        speed = self.gcode.get_int('SPEED', params, default=self.speed,
-                                            minval=1, maxval=30)
-        z_start_position = self.gcode.get_float(
-            'Z', params, default=10., minval=self.z_offset, maxval=70.)
-        x_start_position = self.gcode.get_float('X', params, default=pos[0])
-        y_start_position = self.gcode.get_float('Y', params, default=pos[1])
-        start_pos = [x_start_position, y_start_position, z_start_position]
-        self.gcode.respond_info("probe accuracy: at X:%.3f Y:%.3f Z:%.3f\n"
-                                "                "
-                                "and read %d times with speed of %d mm/s" % (
-                                x_start_position, y_start_position,
-                                z_start_position, number_of_reads, speed))
-        # Probe bed "number_of_reads" times
+        self.gcode.respond_info("PROBE_ACCURACY at X:%.3f Y:%.3f Z:%.3f"
+                                " (samples=%d retract=%.3f speed=%.1f\n"
+                                % (pos[0], pos[1], pos[2],
+                                   sample_count, sample_retract_dist, speed))
+        # Probe bed sample_count times
         positions = []
-        for i in range(number_of_reads):
-            # Move Z to start reading position
-            self._move(start_pos, speed)
-            # Probe
+        while len(positions) < sample_count:
+            # Probe position
             pos = self._probe(speed)
             positions.append(pos)
-        # Move Z to start reading position
-        self._move(start_pos, speed)
+            # Retract
+            liftpos = [None, None, pos[2] + sample_retract_dist]
+            self._move(liftpos, speed)
         # Calculate maximum, minimum and average values
         max_value = max([p[2] for p in positions])
         min_value = min([p[2] for p in positions])
@@ -183,9 +177,9 @@ class PrinterProbe:
         median = self._calc_median(positions)[2]
         # calculate the standard deviation
         deviation_sum = 0
-        for i in range(number_of_reads):
-            deviation_sum += pow(positions[i][2] - avg_value, 2)
-        sigma = (deviation_sum / number_of_reads) ** 0.5
+        for i in range(len(positions)):
+            deviation_sum += pow(positions[i][2] - avg_value, 2.)
+        sigma = (deviation_sum / len(positions)) ** 0.5
         # Show information
         self.gcode.respond_info(
             "probe accuracy results: maximum %.6f, minimum %.6f, "