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Comparing Folders and Zip Files Comparing Files with Autosave Version or Version on Disk |
You can use the Comparison Tool to determine and display the differences between selected pairs of files or folders. The comparison process involves three steps:
You can compare files and folders using any of these methods:
From the Current Folder browser:
Select a file or folder, right-click and select Compare Against.
For two files or subfolders in the same folder, select the files or folders, right-click and select Compare Selected Files/Folders.
If you have a file open in the Editor, select Tools > Compare Against. Then, select the option you want: Choose, Autosave Version, or Compare Against Version on Disk. Use Choose to browse to a file, or see Comparing Files with Autosave Version or Version on Disk.
From the MATLAB desktop, select Desktop > Comparison Tool. Then, select the files or folders to compare.
From the command line, use the visdiff function.
If you use Compare Against, select the second item to compare in the Select Files or Folders for Comparison dialog box. Optionally, change the comparison type if multiple types are available for your selections.
If you specify two files or folders to compare using either the Current Folder browser or the visdiff function, then the Comparison Tool automatically performs the default comparison type.
If there are multiple comparison types available for your selections, you can change what type of comparison to run. For example, text, binary, file list, or XML comparison. To change the comparison type, create a new comparison using the Comparison Tool. You can change comparison type in the Select Files or Folders for Comparison dialog box.
For example, from the Current Folder browser, if you select two MAT-files to compare, you get the default comparison type showing information about the variables. To change the comparison type to binary, create a new comparison using the Comparison Tool. See Selecting Files or Folders to Compare from the Comparison Tool.
Comparison Tool report features depend on your comparison type. You can use the tool to:
Compare lines in two text files (some other applications refer to this as a file diff operation). See Comparing Text Files.
Compare and merge variables in two MAT-files. See Comparing MAT-Files.
Determine whether the contents of two binary files match. See Comparing Binary Files.
Compare any combination of folders, zip files, or Simulink manifests to determine:
Which file and folder names are unique to each list
If files and folders with the same name in each list have the same content
Compare XML files:
If you select XML files to compare and you have MATLAB Report Generator™ software, the Comparison Tool runs a hierarchical matching algorithm. You then see a report showing a hierarchical view of the portions of the two XML files that differ.
If you have Simulink Report Generator software, you can select a pair of Simulink models (.mdl files) to compare XML files generated from them.
To select items to compare, see Select the Files or Folders to Compare. You can perform file list comparisons for any combinations of folders, zip files, and Simulink Manifests.
When you use the Comparison Tool to compare two folders (sometimes referred to as directories) or any file list comparison (for example, folder versus zip file), a window opens and presents the contents side by side. The tool enables you to:
Determine the files that the comparison lists have in common.
Determine if files with identical names that are common to both comparison lists also have identical content.
Open a new comparison of two files or folders that are common to both comparison lists, but have different content.
Open a file for viewing in the Editor.
Specify filters to ignore certain files or folders
For list comparisons, if you want to expand the list to see all files in subfolders in one report, select the Include subfolders check box when selecting items to compare. If you do not include subfolders, you can click compare links in the report to open a new comparison of two folders with changed content.
To define filters to exclude unimportant differences, click
the Filters toolbar button,
, or select Comparison > Edit File and Folder
Filters.
The File and Folder Filters dialog box opens. Specify filters to ignore certain files and folders, such as backup files or files created by a revision control system. Filters can save time when reviewing differences, especially when comparing many subfolders. Double-click to edit existing filters.
For example, to ignore all files and folders in a folder named CVS, open the File and Folder Filter dialog box and enter:
CVS/
To ignore all files in a folder named CVS, but not ignore subfolders, enter:
CVS/*
The Comparison Tool displays the contents of the lists side by side and highlights files and subfolders that do not match. The following table describes how the tool highlights each type of change. The status message (such as identical or contents changed) appears in the Change Summary column.
| Change Summary | Highlighting for Folders | Highlighting for Files | Notes |
|---|---|---|---|
| Contents changed | Dark pink | Pink | The contents of the files or folders differ. Click the compare link to investigate. |
| Added | Dark green | Green | File or folder only exists in the right list. |
| Removed | Dark purple | Purple | File or folder only exists in the left list. |
| Identical | None | None |
The following image shows an example of the Comparison Tool when two folders are compared. The results are sorted by Type.
To explore the report you can use the following tools:
You can sort the results by name, type, size, or last modified timestamp by clicking the column headers. For example, click the Type column header to sort by folder and file type, as shown in the preceding figure.
To open a new comparison of two files or folders with changed contents, click the compare link next to file or folder names highlighted in pink.
To open a file in the Editor, click the open link next to a file name.
If the file is present in both folders, you can click links to open the left or right file.
If subfolders are very large and contain many files, analysis continues in the background. The tool displays the number of items still to be compared at the top of the report, as shown in the next figure. You can click the links to Skip Current item or Cancel All to stop further analysis.
For details on other comparison tool features, see Using Comparison Tool Features.
To select files to compare, see Select the Files or Folders to Compare.
When you use the Comparison Tool to compare two text files, a window opens and presents the two files side by side. Symbols indicate how you can adjust the files to make them match. This feature can be useful when you want to compare the latest version of a text file to an autosave version.
The Comparison Tool report displays the files side by side and highlights lines that do not match, as follows:
Dark pink highlighting indicates changed characters within lines.
Pink highlighting and an x between the two files indicate that the content of the lines differs between the two files.
Green highlighting and a right (>) or left (< ) angle bracket between the two files indicate a line that exists on one side only.
The Comparison Tool attempts to match lines and detects local text that is added, deleted, or changed. It does not do a simple line-by-line comparison. In the previous image, for example, the tool determines that lengthofline.m has a line of code that does not exist in lengthofline2.m and highlights it (line 23) in green. Also, notice that the tool takes the additional line into account and determines that the line containing the end statement in each file matches, even though the end statement does not occur on the same line number.
If the files you are comparing are extremely long, the tool could run out of memory while attempting to perform the file comparison. In which case, the message,
Maximum file length exceeded. Defaulting to line-by-line comparison.
appears. In a line-by-line comparison, the tool highlights the lines containing the end statement because in performing this operation, it finds that the last line in one file does not match the last line in the other file.
Because text files can be lengthy, the Comparison Tool provides toolbar buttons to help you step through the results from one difference to the next.
To navigate through comparison results:
Click the down arrow toolbar button to go to the next set of lines that differ.
If no additional sets of lines differ, the down arrow takes you to the end of the file.
Click the up arrow toolbar button to go to a previous set of lines that differ.
If no previous set of lines differ, the up arrow takes you to the beginning of the file.
Alternatively, use the menu items Comparison > Next or Previous.
To see a summary of differences between two text files, scroll to the bottom of the Comparison Tool and view the list, which contains information such as:
Number of matching lines: 52
Number of unmatched lines in left-hand file: 12
Number of unmatched lines in right-hand file: 15
You may want to hide whitespace differences to help you distinguish between functional changes and changes to indentation.
Use the toolbar button,
, to toggle the display of differences
only involving whitespace characters, or select Comparison > Ignore Whitespace.
You can specify whether to show only differences or entire files. It can be useful to hide unmodified lines in large text comparison reports. When you are showing differences only and sections are hidden, the report displays messages like the following: 10 unmodified lines hidden.
Use the toolbar button,
, to toggle the display
of sections of the report that do not contain any differences, or
select Comparison > Show
Differences Only.
To increase or decrease the line lengths of the text files in the comparison display, edit the number in the Columns visible field. Resize the window, if necessary.
For details on other comparison tool features, see Using Comparison Tool Features.
Click Save As on the toolbar to save a copy of the comparison report as an HTML file. The tool creates a corresponding folder containing the style sheet and JavaScript files that control the report highlighting. To preserve the highlighting, keep the folder with the HTML file.
From the Editor you can compare one open text file with another, or you can choose to compare the latest version of a file in the Editor to an autosave version or a saved version. For an example, follow these steps:
Open one of the text files you want to compare in the Editor.
To open the example file provided, lengthofline.m, run the following command in the Command Window:
open(fullfile(matlabroot,'help','techdoc','matlab_env',... 'examples','lengthofline.m'))
Select Tools > Compare Against > Choose (or Save and Compare Against if your file is modified).
Navigate to the file you want to compare against, select the file, and click Open. To open the example file provided, select lengthofline2.m from the folder where you found lengthofline.m. Other options available are:
To compare the open file to the Editor's automatic copy (filename.asv) select Tools > Compare Against > Autosave Version. For more information, see Autosaving Files.
To compare an open file that has been changed, but not saved, to the saved version, select Tools > Compare Against Version on Disk
Note To select files to compare, see Select the Files or Folders to Compare. |
You can use the Comparison Tool to compare two MAT-files. The tool presents the variables in the two files side by side, which enables you to:
View and sort by the name, size, class, and change summary of all variables.
View details of differences between variables, to see which fields of a structure are different, and view differences in individual elements of an array.
Merge changes between files by copying modified variables from one file to the other (Caution: No undo).
See which variables are common to each file and which are unique.
Load the contents of the variables into the Variable Editor by clicking the name of that variable.
Load the MAT-files into the workspace by clicking a Load link.
Save a copy of the report as an HTML file. Click Save As on the toolbar.
The Comparison Tool report highlights changes in variables as follows.
| Change Summary | Highlighting | Notes |
|---|---|---|
| Modified | Pink | Values of the variable differ between the two files. Click the View differences button  to investigate. A new
variable comparison report opens to display differences in individual
array elements or differing fields of a structure. Double-click pink
rows or cells to investigate further layers of differences. |
| Added | Green | Variable only exists in right file. |
| Removed | Purple | Variable only exists in right file. |
| Identical | None | Variable identical in both files. |
| Class changed | Pink (only in Class columns) | Variable data class changed. Click the View differences button to investigate. |
Click the Merge button
in the Merge column to copy modified
variables from one file to the other.
The following image shows the results when you compare two files, data1.mat and data2.mat.
Note To select files to compare, see Select the Files or Folders to Compare. |
You can use the Comparison Tool to compare two binary files such as DLL files or MEX-files. Also, you can select the Binary comparison type for any pair of files with a choice of comparison types.
If the files are the same, the tool displays the message: The files are identical.
If the files differ, the tool displays the message: The files are different.
You can use the Comparison Tool for the following tasks:
To compare two files or folders from the Comparison Tool, follow these steps:
Select Desktop > Comparison Tool to open the tool.
The Comparison Tool opens a window that is empty, except for the title bar, a menu bar, and a toolbar.
Compare files or folders by clicking the New comparison
button
or by selecting File > New Comparison.
The dialog box Select Files or Folders for Comparison appears.
In the dialog box, select two files or folders to compare.
Use the drop-down lists or the Browse buttons
to locate
and select the items that you want to compare.
You also can drag and drop a file or folder from Windows Explorer to the left and right file and folder fields.
Optionally, choose the comparison type you want to use. Either use the default Comparison type value, or if multiple comparison types are available, select a different one from the list. For example, for text files you could select text or binary comparison types.
Click Compare.
To move the file or folder on the left side to the right side
and vice versa, select File > Swap Sides, or click the Swap
sides button
.
After making changes to and saving the files in the Editor,
update the results in the Comparison Tool by selecting File > Refresh or clicking the Refresh button
.
To find a phrase in the current display, select Edit > Find, or click the Find text button
. The resulting Find dialog
box is the same as the one you use in the Command Window. For more
information, see Find Text Currently Displayed in the Command Window.
You can perform another file comparison by selecting File > New Comparison, or by clicking the toolbar button
.
New comparisons open additional tabs in the Comparison Tool.
You can see the results of previous comparisons in the current session by selecting that comparison's tab entry on the document bar at the bottom of the window. If you close the Comparison Tool, the current and previous comparisons are lost.
Use the visdiff function to open the Comparison Tool from the Command Window.
visdiff(fileorfoldername1, fileorfoldername2)
For example, type:
visdiff('lengthofline.m', 'lengthofline2.m')
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