From 792d14492e894bba04fb4a48cb4846253db2535c Mon Sep 17 00:00:00 2001
From: Kris Fedorenko <1648280+krisfed@users.noreply.github.com>
Date: Thu, 19 Jun 2025 11:20:43 -0400
Subject: [PATCH 1/6] First draft of partial read

---
 PythonModule/ZarrPy.py                 |  12 ++++-
 Zarr.m                                 |  56 ++++++++++++++++++-
 test/dataFiles/grp_v2/smallArr/.zarray |   1 +
 test/dataFiles/grp_v2/smallArr/0.0     | Bin 0 -> 96 bytes
 test/tZarrRead.m                       |  71 +++++++++++++++++++++++++
 zarrread.m                             |  26 +++++++--
 6 files changed, 157 insertions(+), 9 deletions(-)
 create mode 100644 test/dataFiles/grp_v2/smallArr/.zarray
 create mode 100644 test/dataFiles/grp_v2/smallArr/0.0

diff --git a/PythonModule/ZarrPy.py b/PythonModule/ZarrPy.py
index 3e51709..0f61b34 100644
--- a/PythonModule/ZarrPy.py
+++ b/PythonModule/ZarrPy.py
@@ -81,12 +81,16 @@ def writeZarr (kvstore_schema, data):
     zarr_file[...] = data
 
 
-def readZarr (kvstore_schema):
+def readZarr (kvstore_schema, starts, ends, strides):
     """
     Reads a subset of data from a Zarr file.
 
     Parameters:
     - kvstore_schema (dictionary): Schema for the file store (local or remote)
+    - starts (list): Array of start indices for each dimension (0-based)
+    - ends (list): Array of end indices for each dimension (elements 
+                   at the end index will not be read)
+    - strides (list): Array of strides for each dimensions
     
     Returns:
     - numpy.ndarray: The subset of the data read from the Zarr file.
@@ -96,6 +100,10 @@ def readZarr (kvstore_schema):
         'kvstore': kvstore_schema,
     }).result()
     
+    # Construct the indexing slices
+    slices = tuple(slice(start, end, stride) for start, end, stride in zip(starts, ends, strides))
+
     # Read a subset of the data
-    data = zarr_file[...].read().result()
+    data = zarr_file[slices].read().result()
+    #data = zarr_file[...].read().result()
     return data
diff --git a/Zarr.m b/Zarr.m
index e8acc5a..ddd56b9 100644
--- a/Zarr.m
+++ b/Zarr.m
@@ -53,6 +53,38 @@
             isZgroup = isfile(fullfile(path, '.zgroup'));
         end
 
+        function newParams = validatePartialReadParams(params, dims, defaultValues)
+            % Validate the parameters for partial read (Start, Stride,
+            % Count)
+
+            arguments (Output)
+                newParams (1,:) int64
+            end
+            
+            if isempty(params)
+                newParams = defaultValues;
+                return
+            end
+
+            % Allow using a scalar value for indexing into row or column
+            % datasets
+            if isscalar(params) && any(dims==1) && numel(dims)==2
+                newParams = defaultValues;
+                % use the provided value for the non-scalar dimension
+                newParams(dims~=1) = params;
+                return
+            end
+
+            if numel(params) ~= numel(dims)
+                error("MATLAB:Zarr:badPartialReadDimensions",...
+                    "Length of parameters for partial reading " +...
+                    "(Start, Stride, Count) must be the same "+...
+                    "as the number of dataset dimensions.")
+            end
+
+            newParams = params;
+        end
+
         function resolvedPath = getFullPath(path)
             % Given a path, resolves it to a full path. The trailing
             % directories do not have to exist.
@@ -200,7 +232,7 @@ function makeZarrGroups(existingParentPath, newGroupsPath)
         end
 
         
-        function data = read(obj)
+        function data = read(obj, start, count, stride)
             % Function to read the Zarr array
 
             % If the Zarr array is local, verify that it is a valid folder
@@ -214,7 +246,27 @@ function makeZarrGroups(existingParentPath, newGroupsPath)
                 end
             end
 
-            ndArrayData = py.ZarrPy.readZarr(obj.KVStoreSchema);
+            % Validate partial read parameters
+            info = zarrinfo(obj.Path);
+            numDims = numel(info.shape);
+            start = Zarr.validatePartialReadParams(start, info.shape,...
+                ones([1,numDims]));
+            stride = Zarr.validatePartialReadParams(stride, info.shape,...
+                ones([1,numDims])); 
+            maxCount = (int64(info.shape') - start + 1)./stride; % has to be a row vector
+            count = Zarr.validatePartialReadParams(count, info.shape,...
+                maxCount); 
+
+            % Convert partial read parameters to tensorstore-style
+            % indexing
+            start = start - 1; % tensorstore is 0-based
+            % Tensorstore uses end index instead of count
+            % (it does NOT include element at the end index)
+            endInds = start + stride.*count;
+
+            % Read the data
+            ndArrayData = py.ZarrPy.readZarr(obj.KVStoreSchema,...
+                start, endInds, stride);
 
             % Store the datatype
             obj.Datatype = ZarrDatatype.fromTensorstoreType(ndArrayData.dtype.name);
diff --git a/test/dataFiles/grp_v2/smallArr/.zarray b/test/dataFiles/grp_v2/smallArr/.zarray
new file mode 100644
index 0000000..b0f27fa
--- /dev/null
+++ b/test/dataFiles/grp_v2/smallArr/.zarray
@@ -0,0 +1 @@
+{"chunks":[3,4],"compressor":null,"dimension_separator":".","dtype":"<f8","fill_value":null,"filters":null,"order":"C","shape":[3,4],"zarr_format":2}
\ No newline at end of file
diff --git a/test/dataFiles/grp_v2/smallArr/0.0 b/test/dataFiles/grp_v2/smallArr/0.0
new file mode 100644
index 0000000000000000000000000000000000000000..3f0207f0459082332c55b5f1b902cf00c5029db0
GIT binary patch
literal 96
scmZQz0D%woV2VM&0Yb|_X%#5V0HsBsv;ve?gVG#OS^`QdL1_&K00d421ONa4

literal 0
HcmV?d00001

diff --git a/test/tZarrRead.m b/test/tZarrRead.m
index 3699ff2..5ecd9c7 100644
--- a/test/tZarrRead.m
+++ b/test/tZarrRead.m
@@ -7,6 +7,7 @@
         % Path for read functions
         GrpPathRead = "dataFiles/grp_v2"
         ArrPathRead = "dataFiles/grp_v2/arr_v2"
+        ArrPathReadSmall = "dataFiles/grp_v2/smallArr"
         ArrPathReadV3 = "dataFiles/grp_v3/arr_v3"
 
         ExpData = load(fullfile(pwd,"dataFiles","expZarrArrData.mat"))
@@ -28,6 +29,42 @@ function verifyArrayData(testcase)
             testcase.verifyEqual(actArrData,expArrData,'Failed to verify array data.');
         end
 
+        function verifyPartialArrayData(testcase)
+            % Verify array data using zarrread function with Start/Stride/Count.
+
+            % The full data in the small array is
+            % 
+            % 1    4    7   10
+            % 2    5    8   11
+            % 3    6    9   12
+            zpath = testcase.ArrPathReadSmall;
+
+            % Start
+            actData = zarrread(zpath, Start=[2, 3]);
+            expData = [8, 11; 9, 12];
+            testcase.verifyEqual(actData,expData,...
+                'Failed to verify reading with Start.');
+
+            % Count
+            actData = zarrread(zpath, Count=[2, 1]);
+            expData = [1;2];
+            testcase.verifyEqual(actData,expData,...
+                'Failed to verify reading with Count.');
+
+            % Stride
+            actData = zarrread(zpath, Stride=[3, 2]);
+            expData = [1, 7];
+            testcase.verifyEqual(actData,expData,...
+                'Failed to verify reading with Stride.');
+
+            % Start, Stride, and Count
+            actData = zarrread(zpath,...
+                Start=[2, 1], Stride=[1, 2], Count=[1,2]);
+            expData = [2, 8];
+            testcase.verifyEqual(actData,expData,...
+                'Failed to verify reading with Start, Stride, and Count.');
+        end
+
         function verifyArrayDataRelativePath(testcase)
             % Verify array data if the input is using relative path to the
             % array.
@@ -83,5 +120,39 @@ function invalidFilePath(testcase)
             errID = 'MATLAB:Zarr:invalidZarrObject';
             testcase.verifyError(@()zarrread(inpPath),errID);
         end
+
+        function invalidPartialReadParams(testcase)
+            % Verify zarrread errors when invalid partial read
+            % Start/Stride/Count are used
+            
+            zpath = testcase.ArrPathReadSmall; % a 2D array, 3x4
+    
+            errID = 'MATLAB:Zarr:badPartialReadDimensions';
+            wrongNumberOfDimensions = [1,1,1];
+            testcase.verifyError(...
+                @()zarrread(zpath,Start=wrongNumberOfDimensions),...
+                errID);
+            testcase.verifyError(...
+                @()zarrread(zpath,Stride=wrongNumberOfDimensions),...
+                errID);
+            testcase.verifyError(...
+                @()zarrread(zpath,Count=wrongNumberOfDimensions),...
+                errID);
+
+            errID = 'MATLAB:validators:mustBeRow';
+            wrongSize = [1; 1];
+            testcase.verifyError(...
+                @()zarrread(zpath,Start=wrongSize),...
+                errID);
+            testcase.verifyError(...
+                @()zarrread(zpath,Stride=wrongSize),...
+                errID);
+            testcase.verifyError(...
+                @()zarrread(zpath,Count=wrongSize),...
+                errID);
+
+            %TODO: negative values, wrong datatypes, out of bounds
+           
+        end
     end
 end
\ No newline at end of file
diff --git a/zarrread.m b/zarrread.m
index 5195410..7691a49 100644
--- a/zarrread.m
+++ b/zarrread.m
@@ -1,16 +1,32 @@
-function data = zarrread(filepath)
+function data = zarrread(filepath, options)
 %ZARRREAD Read data from Zarr array
 %   DATA = ZARRREAD(FILEPATH) retrieves all the data from the Zarr array
-%   located at FILEPATH.
-% The datatype of DATA is the MATLAB equivalent of the Zarr datatype of the
-% array located at FILEPATH.
+%   located at FILEPATH. The datatype of DATA is the MATLAB equivalent of 
+%   the Zarr datatype of the array located at FILEPATH.
+% 
+%   DATA = ZARRREAD(FILEPATH, Start=start) retrieves a subset of the data 
+%   from the Zarr array located at FILEPATH. Start is a row vector of 
+%   one-based indices of the first element to be read in each dimension. 
+% 
+%   DATA = ZARRREAD(FILEPATH, Count=count) retrieves a subset of the data 
+%   from the Zarr array located at FILEPATH. Count is a row vector
+%   of number of elements to be read in each dimension. 
+% 
+%   DATA = ZARRREAD(FILEPATH, Stride=stride) retrieves a subset of the data 
+%   from the Zarr array located at FILEPATH. Stride is a row vector of 
+%   spaces between indices along each dimension. A value of 1 accesses 
+%   adjacent elements in the corresponding dimension, a value of 2
+%   accesses every other element in the corresponding dimension, etc.
 
 %   Copyright 2025 The MathWorks, Inc.
 
 arguments
     filepath {mustBeTextScalar, mustBeNonzeroLengthText}
+    options.Start {mustBeInteger, mustBePositive, mustBeRow} = double.empty(1,0);
+    options.Count {mustBeInteger, mustBePositive, mustBeRow} = double.empty(1,0);
+    options.Stride {mustBeInteger, mustBePositive, mustBeRow} = double.empty(1,0);
 end
 
 zarrObj = Zarr(filepath);
-data = zarrObj.read;
+data = zarrObj.read(options.Start, options.Count, options.Stride);
 end
\ No newline at end of file

From 1bd22db8b0008bf79d081fbb25977a6055fcc334 Mon Sep 17 00:00:00 2001
From: Kris Fedorenko <1648280+krisfed@users.noreply.github.com>
Date: Thu, 19 Jun 2025 12:04:42 -0400
Subject: [PATCH 2/6] mustBeRow not available before R2024b - for now allow
 other shapes and reshape them into row vectors

---
 PythonModule/ZarrPy.py |  8 ++++----
 test/tZarrRead.m       | 12 ------------
 zarrread.m             |  6 +++---
 3 files changed, 7 insertions(+), 19 deletions(-)

diff --git a/PythonModule/ZarrPy.py b/PythonModule/ZarrPy.py
index 0f61b34..6a182b9 100644
--- a/PythonModule/ZarrPy.py
+++ b/PythonModule/ZarrPy.py
@@ -87,10 +87,10 @@ def readZarr (kvstore_schema, starts, ends, strides):
 
     Parameters:
     - kvstore_schema (dictionary): Schema for the file store (local or remote)
-    - starts (list): Array of start indices for each dimension (0-based)
-    - ends (list): Array of end indices for each dimension (elements 
+    - starts (numpy.ndarray): Array of start indices for each dimension (0-based)
+    - ends (numpy.ndarray): Array of end indices for each dimension (elements 
                    at the end index will not be read)
-    - strides (list): Array of strides for each dimensions
+    - strides (numpy.ndarray): Array of strides for each dimensions
     
     Returns:
     - numpy.ndarray: The subset of the data read from the Zarr file.
@@ -105,5 +105,5 @@ def readZarr (kvstore_schema, starts, ends, strides):
 
     # Read a subset of the data
     data = zarr_file[slices].read().result()
-    #data = zarr_file[...].read().result()
+    
     return data
diff --git a/test/tZarrRead.m b/test/tZarrRead.m
index 5ecd9c7..b54071a 100644
--- a/test/tZarrRead.m
+++ b/test/tZarrRead.m
@@ -139,18 +139,6 @@ function invalidPartialReadParams(testcase)
                 @()zarrread(zpath,Count=wrongNumberOfDimensions),...
                 errID);
 
-            errID = 'MATLAB:validators:mustBeRow';
-            wrongSize = [1; 1];
-            testcase.verifyError(...
-                @()zarrread(zpath,Start=wrongSize),...
-                errID);
-            testcase.verifyError(...
-                @()zarrread(zpath,Stride=wrongSize),...
-                errID);
-            testcase.verifyError(...
-                @()zarrread(zpath,Count=wrongSize),...
-                errID);
-
             %TODO: negative values, wrong datatypes, out of bounds
            
         end
diff --git a/zarrread.m b/zarrread.m
index 7691a49..c7ca127 100644
--- a/zarrread.m
+++ b/zarrread.m
@@ -22,9 +22,9 @@
 
 arguments
     filepath {mustBeTextScalar, mustBeNonzeroLengthText}
-    options.Start {mustBeInteger, mustBePositive, mustBeRow} = double.empty(1,0);
-    options.Count {mustBeInteger, mustBePositive, mustBeRow} = double.empty(1,0);
-    options.Stride {mustBeInteger, mustBePositive, mustBeRow} = double.empty(1,0);
+    options.Start (1,:) {mustBeInteger, mustBePositive} = [];
+    options.Count (1,:) {mustBeInteger, mustBePositive} = [];
+    options.Stride (1,:) {mustBeInteger, mustBePositive} = [];
 end
 
 zarrObj = Zarr(filepath);

From 603eb9beede7626575438d4ec5f181d450fe051d Mon Sep 17 00:00:00 2001
From: Kris Fedorenko <1648280+krisfed@users.noreply.github.com>
Date: Thu, 19 Jun 2025 12:26:53 -0400
Subject: [PATCH 3/6] Adding test for scalar Start/Stride/Count

---
 test/dataFiles/grp_v2/vectorData/.zarray |   1 +
 test/dataFiles/grp_v2/vectorData/0.0     | Bin 0 -> 80 bytes
 test/tZarrRead.m                         |  13 +++++++++++++
 3 files changed, 14 insertions(+)
 create mode 100644 test/dataFiles/grp_v2/vectorData/.zarray
 create mode 100644 test/dataFiles/grp_v2/vectorData/0.0

diff --git a/test/dataFiles/grp_v2/vectorData/.zarray b/test/dataFiles/grp_v2/vectorData/.zarray
new file mode 100644
index 0000000..d3eb18f
--- /dev/null
+++ b/test/dataFiles/grp_v2/vectorData/.zarray
@@ -0,0 +1 @@
+{"chunks":[1,10],"compressor":null,"dimension_separator":".","dtype":"<f8","fill_value":null,"filters":null,"order":"C","shape":[1,10],"zarr_format":2}
\ No newline at end of file
diff --git a/test/dataFiles/grp_v2/vectorData/0.0 b/test/dataFiles/grp_v2/vectorData/0.0
new file mode 100644
index 0000000000000000000000000000000000000000..f23fe4566cf8d8f919b6380010e5479d090dc5f5
GIT binary patch
literal 80
ncmZQz0D%woV2Xjk0YY;?X#prL0;MIOv<#G1fYM4(TEzhXv;zb-

literal 0
HcmV?d00001

diff --git a/test/tZarrRead.m b/test/tZarrRead.m
index b54071a..bb7bef3 100644
--- a/test/tZarrRead.m
+++ b/test/tZarrRead.m
@@ -8,6 +8,7 @@
         GrpPathRead = "dataFiles/grp_v2"
         ArrPathRead = "dataFiles/grp_v2/arr_v2"
         ArrPathReadSmall = "dataFiles/grp_v2/smallArr"
+        ArrPathReadVector = "dataFiles/grp_v2/vectorData"
         ArrPathReadV3 = "dataFiles/grp_v3/arr_v3"
 
         ExpData = load(fullfile(pwd,"dataFiles","expZarrArrData.mat"))
@@ -65,6 +66,18 @@ function verifyPartialArrayData(testcase)
                 'Failed to verify reading with Start, Stride, and Count.');
         end
 
+        function verifyPartialVectorData(testcase)
+            % Verify that specifying a scalar value for Start/Stride/Count
+            % for vector datasets works as expected
+
+            zpath = testcase.ArrPathReadVector; % data is 1:10
+
+            expData = [2,5];
+            actData = zarrread(zpath, Start=2, Stride=3, Count=2);
+            testcase.verifyEqual(actData,expData,...
+                'Failed to verify using scalar Start, Stride, and Count.');
+        end
+
         function verifyArrayDataRelativePath(testcase)
             % Verify array data if the input is using relative path to the
             % array.

From 6f763b9761b453bb76453b74e3faa1e3cf65762f Mon Sep 17 00:00:00 2001
From: Kris Fedorenko <1648280+krisfed@users.noreply.github.com>
Date: Thu, 19 Jun 2025 12:47:24 -0400
Subject: [PATCH 4/6] Included info about defaults for Start/Stride/Count in
 M-help

---
 test/tZarrRead.m | 2 +-
 zarrread.m       | 9 +++++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/test/tZarrRead.m b/test/tZarrRead.m
index bb7bef3..262c77b 100644
--- a/test/tZarrRead.m
+++ b/test/tZarrRead.m
@@ -60,7 +60,7 @@ function verifyPartialArrayData(testcase)
 
             % Start, Stride, and Count
             actData = zarrread(zpath,...
-                Start=[2, 1], Stride=[1, 2], Count=[1,2]);
+                Start=[2, 1], Stride=[1, 2], Count=[1, 2]);
             expData = [2, 8];
             testcase.verifyEqual(actData,expData,...
                 'Failed to verify reading with Start, Stride, and Count.');
diff --git a/zarrread.m b/zarrread.m
index c7ca127..f8f93ad 100644
--- a/zarrread.m
+++ b/zarrread.m
@@ -6,17 +6,22 @@
 % 
 %   DATA = ZARRREAD(FILEPATH, Start=start) retrieves a subset of the data 
 %   from the Zarr array located at FILEPATH. Start is a row vector of 
-%   one-based indices of the first element to be read in each dimension. 
+%   one-based indices of the first element to be read in each dimension.
+%   Default is to read all the elements starting from the first (Start=
+%   [1,1,..].
 % 
 %   DATA = ZARRREAD(FILEPATH, Count=count) retrieves a subset of the data 
 %   from the Zarr array located at FILEPATH. Count is a row vector
-%   of number of elements to be read in each dimension. 
+%   of number of elements to be read in each dimension. Default is to read 
+%   all the available elements (based on dimension size and the specified 
+%   Start and Stride).
 % 
 %   DATA = ZARRREAD(FILEPATH, Stride=stride) retrieves a subset of the data 
 %   from the Zarr array located at FILEPATH. Stride is a row vector of 
 %   spaces between indices along each dimension. A value of 1 accesses 
 %   adjacent elements in the corresponding dimension, a value of 2
 %   accesses every other element in the corresponding dimension, etc.
+%   Default is to read all elements without skipping (Stride=[1,1,...])
 
 %   Copyright 2025 The MathWorks, Inc.
 

From 9936f798b0caf6a8b7826b5b93ea9594f5a3de0b Mon Sep 17 00:00:00 2001
From: Kris Fedorenko <1648280+krisfed@users.noreply.github.com>
Date: Fri, 20 Jun 2025 11:49:40 -0400
Subject: [PATCH 5/6] Error message update

---
 Zarr.m | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Zarr.m b/Zarr.m
index ddd56b9..5018aab 100644
--- a/Zarr.m
+++ b/Zarr.m
@@ -77,9 +77,9 @@
 
             if numel(params) ~= numel(dims)
                 error("MATLAB:Zarr:badPartialReadDimensions",...
-                    "Length of parameters for partial reading " +...
-                    "(Start, Stride, Count) must be the same "+...
-                    "as the number of dataset dimensions.")
+                    "Number of elements in " +...
+                    "Start/Stride/Count must be the same "+...
+                    "as the number of Zarr array dimensions.")
             end
 
             newParams = params;

From 78892035145507ec2b1e0cdf05f2985e2c814678 Mon Sep 17 00:00:00 2001
From: Kris Fedorenko <1648280+krisfed@users.noreply.github.com>
Date: Fri, 27 Jun 2025 06:57:33 -0400
Subject: [PATCH 6/6] Address feedback and add doc

---
 Zarr.m               | 30 +++++++++++++++++++-----------
 doc/documentation.md | 25 +++++++++++++++++++++++--
 doc/examples.md      | 12 ++++++++++++
 zarrread.m           | 38 +++++++++++++++++++-------------------
 4 files changed, 73 insertions(+), 32 deletions(-)

diff --git a/Zarr.m b/Zarr.m
index 5018aab..3088425 100644
--- a/Zarr.m
+++ b/Zarr.m
@@ -53,12 +53,19 @@
             isZgroup = isfile(fullfile(path, '.zgroup'));
         end
 
-        function newParams = validatePartialReadParams(params, dims, defaultValues)
-            % Validate the parameters for partial read (Start, Stride,
+        function newParams = processPartialReadParams(params, dims,...
+                defaultValues, paramName)
+            % Process the parameters for partial read (Start, Stride,
             % Count)
+            arguments (Input)
+                params % Start/Stride/Count parameter to be validated
+                dims (1,:) double  % Zarr array dimensions
+                defaultValues (1,:) 
+                paramName (1,1) string 
+            end
 
             arguments (Output)
-                newParams (1,:) int64
+                newParams (1,:) int64 % must be integers for tensorstore
             end
             
             if isempty(params)
@@ -78,8 +85,9 @@
             if numel(params) ~= numel(dims)
                 error("MATLAB:Zarr:badPartialReadDimensions",...
                     "Number of elements in " +...
-                    "Start/Stride/Count must be the same "+...
-                    "as the number of Zarr array dimensions.")
+                    "%s must be the same "+...
+                    "as the number of Zarr array dimensions.",...
+                    paramName)
             end
 
             newParams = params;
@@ -249,13 +257,13 @@ function makeZarrGroups(existingParentPath, newGroupsPath)
             % Validate partial read parameters
             info = zarrinfo(obj.Path);
             numDims = numel(info.shape);
-            start = Zarr.validatePartialReadParams(start, info.shape,...
-                ones([1,numDims]));
-            stride = Zarr.validatePartialReadParams(stride, info.shape,...
-                ones([1,numDims])); 
+            start = Zarr.processPartialReadParams(start, info.shape,...
+                ones([1,numDims]), "Start");
+            stride = Zarr.processPartialReadParams(stride, info.shape,...
+                ones([1,numDims]), "Stride"); 
             maxCount = (int64(info.shape') - start + 1)./stride; % has to be a row vector
-            count = Zarr.validatePartialReadParams(count, info.shape,...
-                maxCount); 
+            count = Zarr.processPartialReadParams(count, info.shape,...
+                maxCount, "Count"); 
 
             % Convert partial read parameters to tensorstore-style
             % indexing
diff --git a/doc/documentation.md b/doc/documentation.md
index 9d6a556..6ae5757 100644
--- a/doc/documentation.md
+++ b/doc/documentation.md
@@ -68,11 +68,32 @@ do not already exist. If `FILEPATH` exists already, the contents are overwritten
 Write the MATLAB variable data (specified by DATA) to the path specified by `FILEPATH`.
 The size of `DATA` must match the size of the Zarr array specified during creation.
 
-## `DATA = zarrread(FILEPATH)`
-Retrieve all the data from the Zarr array located at `FILEPATH`.
+## `DATA = zarrread(FILEPATH, Name=Value)`
+Retrieve data from the Zarr array located at `FILEPATH`.
 The datatype of DATA is the MATLAB equivalent of the Zarr datatype of the array
 located at `FILEPATH`.
 
+###	Name - Value Pairs
+```
+Start    - a row vector of one-based indices of the first 
+           elements to be read in each dimension. If you 
+           do not specify start, then the function starts 
+           reading the dataset from the first index along 
+           each dimension.
+
+Count    - a row vector of numbers of elements to
+           be read in each dimension. If you do not specify 
+           count, then the function reads data until the end 
+           of each dimension.
+
+Stride   - a row vector of differences between indices along 
+           each dimension. A value of 1 accesses adjacent elements
+           in the corresponding dimension, a value of 2 accesses 
+           every other element in the corresponding dimension, and 
+           so on. If you do not specify stride, then the function 
+           reads data without skipping indices along each dimension.
+```
+
 ## `INFO = zarrinfo(FILEPATH)`
 Read the metadata associated with a Zarr array or group located at `FILEPATH` and return the information in a structure INFO, whose fields are the names of the metadata keys. 
 If `FILEPATH` is a Zarr array (has a valid `.zarray` file), the value of `node_type` is "array"; if `FILEPATH` is a Zarr group (has a valid `.zgroup` file), the value of the field `node_type` is "group".
diff --git a/doc/examples.md b/doc/examples.md
index 3233ea1..a573822 100644
--- a/doc/examples.md
+++ b/doc/examples.md
@@ -6,6 +6,18 @@ filepath = "group1\dset1";
 data = zarrread(filepath)
 ```
 
+### Read a subset of Zarr array
+Read a 2x2 subset of a 3x4 array, starting with the second element in the second dimension, and only reading every other element in the second dimension.
+``` MATLAB
+filepath = "grp_v2/smallArr";
+d = zarrread(filepath, Start=[1,2], Stride=[1,2], Count=[2,2])
+
+d =
+
+     4    10
+     5    11
+```
+
 ### Create and write to a Zarr array
 ``` MATLAB
 filepath   = "myZarrfiles\singleDset";
diff --git a/zarrread.m b/zarrread.m
index f8f93ad..fbfd458 100644
--- a/zarrread.m
+++ b/zarrread.m
@@ -3,25 +3,25 @@
 %   DATA = ZARRREAD(FILEPATH) retrieves all the data from the Zarr array
 %   located at FILEPATH. The datatype of DATA is the MATLAB equivalent of 
 %   the Zarr datatype of the array located at FILEPATH.
-% 
-%   DATA = ZARRREAD(FILEPATH, Start=start) retrieves a subset of the data 
-%   from the Zarr array located at FILEPATH. Start is a row vector of 
-%   one-based indices of the first element to be read in each dimension.
-%   Default is to read all the elements starting from the first (Start=
-%   [1,1,..].
-% 
-%   DATA = ZARRREAD(FILEPATH, Count=count) retrieves a subset of the data 
-%   from the Zarr array located at FILEPATH. Count is a row vector
-%   of number of elements to be read in each dimension. Default is to read 
-%   all the available elements (based on dimension size and the specified 
-%   Start and Stride).
-% 
-%   DATA = ZARRREAD(FILEPATH, Stride=stride) retrieves a subset of the data 
-%   from the Zarr array located at FILEPATH. Stride is a row vector of 
-%   spaces between indices along each dimension. A value of 1 accesses 
-%   adjacent elements in the corresponding dimension, a value of 2
-%   accesses every other element in the corresponding dimension, etc.
-%   Default is to read all elements without skipping (Stride=[1,1,...])
+%
+%   DATA = ZARRREAD(..., Start=start) retrieves a subset of the data from
+%   the Zarr array. Specify start as a row vector of one-based indices of
+%   the first elements to be read in each dimension. If you do not specify
+%   start, then the function starts reading the dataset from the first
+%   index along each dimension.
+%
+%   DATA = ZARRREAD(..., Count=count) retrieves a subset of the data from
+%   the Zarr array. Specify count as a row vector of numbers of elements to
+%   be read in each dimension. If you do not specify count, then the
+%   function reads data until the end of each dimension.
+%
+%   DATA = ZARRREAD(..., Stride=stride) retrieves a subset of the data from
+%   the Zarr array. Specify stride as a row vector of differences between
+%   indices along each dimension. A value of 1 accesses adjacent elements
+%   in the corresponding dimension, a value of 2 accesses every other
+%   element in the corresponding dimension, and so on. If you do not
+%   specify stride, then the function reads data without skipping indices
+%   along each dimension.
 
 %   Copyright 2025 The MathWorks, Inc.