Excel merge and center Unique values


I have a table of data with multiple column but few of the columns has same value. Can you guide me which node to be used to merge the unique values and keep it like this way.

Tried via continental nodes but didnt get the option for cell merger.

Input Table

Expecting output Table as like below


Hi @Ashwath5245 , although it doesn’t do anything about merging, I have a component that blanks the values for ease of viewing, if that helps at all…

You mentioned the Continental Nodes. What problem did you encounter with them when trying to merge cells? Was it that you didn’t understand how to use them, or something else?

Also, I’m assuming your actual data has many more rows. Have you determined rules by to decide which cells to merge. There would be a big difference between just manually choosing to merge cells in 3 rows or determining which blocks of rows to merge in a much larger table.

Perhaps you could upload some sample data to help people work on a solution.

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With the GroupBy node you can concatenate unique values for each column:


Then apply the following settings in the Manual Aggregation tab:

This gives the following result:

Best wishes/Evert

Excel_merge_and_center_unique_values.knwf (72.6 KB)

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@Ashwath5245 here is an example with merged headers. You could adapt that.

Another option would be to use Openpyxl.

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Thanks for the reply. As per my workflow initial data output, the data was missing values and replaced the cell having “?” with previous value using missing node for that column.

The Blank down Component revert to the initial output and shows the same with “?” instead of names.

I expect the output to remove the duplicate on the multiple cells in the column and merge into one value for that particular group same cell.

The user is part of multiple teams, but the user value should not repeat in each cell of that column, as this is required to filter the data for the end users.

I have installed the continental nodes but really did not understand and where to start initially according the requirements. Tried xls merger, formatter but couldnt find the option to merge.

Thanks for your help

Thank you for the inputs and reply. Looks simple, but I am not getting the exact output.

Do we need to enter the value in the table creator? its bit difficult. I have the output in the from workflow using excel reader and tried to group by as like above and the output comes in horizantal single line.

Thanks for the reply
Is this workflow to bold the First line header of all columns with Color filled?
I am beginner to knime but not sure how this can be incorporate with my current output? Please suggest.


I used the Table Creator just to generate some example input but this could also be coming from an Excel file of course.

Yes, it’s possible to merge unique values from specific columns using the GroupBy node in KNIME. Here’s how you can do it:

Use the GroupBy node.
Choose “Manual Aggregation” .
Choose “Unique Concatenation” as the aggregation method.
This will merge the unique values in the selected column for each group.

I’ve attached a photo for your reference. Please check it to see the configuration.

Hi @Ashwath5245 , I’m not sure what you meant by “as per workflow initial data output”, since you didn’t upload your initial data output.

OK, so doing this merging using the continental nodes does require knowledge of how the continental nodes work (how you define Control Tables, how you create “tags” and how you apply them) and also needs some effort to determine within your data exactly which values are to be merged.

I created some initial data based on your screenshot. Ideally you would have uploaded some actual sample data in a form that we could use, to save on having to create sample data.

However, I typed in based on the screenshot, and extended it as follows:


I took the approach that having used the “Blank Down Strings” component, I would have missing values like this:


and my rule then was that anywhere where a missing value existed, we would want the output to Excel to be merged with the cell above.

(Note there is no concept of “merged” cells in a KNIME table. So if you were expecting merged cells in KNIME I’m afraid that isn’t an option. My assumption is as per your title, that you want to merge the cells on output to Excel).

I have uploaded a workflow to the community hub

The primary part was to find all the places where the Missing Values were present, and generate a control table that marked the “unique” groupings:

resulting in the following “Control Table”, where row 1 represents the header row in the final Excel output.
compare that control table with the data and (ignoring the blank “header” row) you should be able to see the correlation between the groups of data and the “control tags”

The end result is the following excel spreadsheet:


In order to achieve this, I made use of four different additional components that I have written over time.

The “Blank Down Strings” component already mentioned above


Two components for allowing XLS Format models to be “collected” within a loop and then “retrieved” once the loop is completed (to avoid KNIME complaining that a branch is leaving the loop)

and finally a convenience component for modifying a path variable

I haven’t got time to write up how all the parts of this workflow work, as that would be a training course in itself, but I have added comments beneath the nodes and as annotation, so if you have specific questions about how a particular part works, feel free to ask.

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I’ve updated the original flow I posted at

I have added two new components which generalise the case of vertically merging cells where they have the same value as the row above. This can be seen demonstrated in the lower flow here:

The two new components in the lower flow replace the coloured sections in the upper flow.

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Hi takbb,

Thanks for your help and efforts. Can you please guide me one thing how to integrate the above workflow with my workflow? Directly copy the nodes and paste into my workflow? make it as metanode or component and integrate into the existing workflow.

Currently, my workflow configured to write the output in Excel writer node and send it to email.

Note: In my workflow I got blank values and replaced with the previous values using the missing value node and thus the reason got repeated with same names.

Hi @ashwath5245, it’s a bit difficult to be certain as I don’t know what your data looks like, but essentially the work replaces the Excel Writer, so I’d imagine the integration would look like this (only with prettier lines :wink:

And yes, copying and pasting from one workflow into the other is a possibility. You would of course need to do any configuration changes to match your existing workflow. You can of course also drag and drop each component from the hub onto your workflow, and build the workflow as show in the above picture.

Thank you for the guidance. I integrated the components to current workflow but getting failed in the below string to date/time node. Kindly suggest


Hi @Ashwath5245 , you aren’t giving us many clues as we can’t see how your workflow is configured, and we have no way of knowing why your data looks like it does.

All I can tell you is that it is clear that String to Date&Time node is being presented with data which does not represent valid dates. What are you expecting?

Are you asking why your data looks like it does? Is this the xls control table from one of the components? If it is I’m going to guess that you have mis-connected some nodes somewhere and that you meant to pass it your actual data, but given that the latest screenshot shows a bunch of nodes and I have no idea what you’ve got them connected to, there isn’t much else I can tell you.

Please keep in mind that if you don’t actually share a workflow, I can’t see it, and I have no knowledge of what you are doing.

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Hi takbb,

Thanks for your help and reply.

Apologies for the confusion. My workflow configured to pull the user details from the knime business hub with creation & modification date using REST API and exported the output to xls file and send email. Currently stuck on the formatting of xls headers and merging of cells with same name.

Attached my sample workflow for your reference and require formatting of xls properly with headers in bold and tabular column, merging the cells which has duplicates.

Please help to guide how we can use the continental node according to our requirement in the existing workflow. Can you share some documents or training videos of continental nodes’ usage in the order, so that I can go through and give a try as well.
KBH_User Report.knwf (110.5 KB)

Hi @Ashwath5245 , I don’t currently have access to a KNIME business hub, but maybe you could upload an xlsx containing some sample (anonymized) data that is the output from the Rule Engine in your workflow (i.e. the data you want to write to Excel and format )

Apart from merging of cells, what other formatting are you wanting to do? Is it just making the headers bold? I might be able to give you some pointers.

Thanks takbb for your help and support.
Please find the attached sample report which we get in the final output of the workflow.

Required formatting

  1. The columns (A, B, C, E) wherever it repeats (duplicate) should merge to single cell and align it to center. like the below

  2. First row (Header line) to be bolder with filled color if possible.

  3. Apply all table borders
    KBH User Report_dummy.xlsx (12.4 KB)

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Hi @Ashwath5245 ,

I’ll try to do a quick “Continental Nodes for Dummies” (or Continental Tutorial-Lite), as the main Continental FAQ Page is the primary source of info for links and the more detailed description, and to be honest, it took me a while (and a fair bit of reading of posts such as to get to grips with them.

The trouble is that the XLS Formatting nodes are actually really simple but kind of complicated at the same time. The concept is straightforward and yet seems complex…

So where to begin…

In simple terms you have the following concepts. Don’t worry for the moment if my brief definitions don’t fully explain them. I’ll try to expand on them in a moment:

  • Your Data
    You know what this is, and basically its your data that is going to get written to Excel

  • Control Table
    This is a table of information containing a row and column for each row and column that appears in your data, plus an additional row at the top that contains information about your Table Headings (column names). Each cell of this table contains “tags”

  • Tags
    This is just a set of “labels” that you create and assign to one or more cells in your Control Table, to be used by the formatting nodes.

Right, let’s use a small sample of to give some background on how this works. I’m just going to start by showing how you can format the first row to be black text on a light blue (cyan) background

Your Data

I’ve taken a subset of your data for demo purposes, and put it in a Table Creator node

What we want to do is to output this to Excel with the first row being formatted as described above (light blue background with black test).

The first step is to decide which cells in the output xlsx will have formatting applied. That’s fairly easy in this case as it will be the “header row”. Of course in your data table, there is no “header row” as such as the table has dedicated “column headings”, but when it is written to Excel, the first row will be the “header row” which will contain those headings.

Control Table and Tags

To build the Control Table, we “simply” make a table defining all the cell positions in the resultant XLSX where the first row is all “header” rows and the lower rows are all “data” rows. We could start by defining this:

Note that the columns are all “String” datatype as we are placing text strings in each position. The first row of cells say that it is a “header”, and the other rows all have the word “data” in them. I could use any words I wish. They could simply be H and D or they could be Title and Body. It doesn’t matter what “labels” you use. Anyway these labels are what Continental nodes refer to as “tags”, and the above image is the source for making a basic “XLS Control Table” for the continental nodes.

To turn that into an actual control table, we need to rename the columns as A… E and the rowid needs to be come a sequence of numerics beginning at 1. We could do that manually with a few nodes but the Continental Nodes provide us with the XLS Control Table Generator to do exactly that

This is what my workflow looks like so far:

It’s not very fancy yet, and the output is still quite boring, but you can see how the “tags” in the rows of the control table align with the rows and columns in the Excel output.

Clearly we need to do something with that Control Table which is sitting idle, so that it changes the format.

This is where we start using the Continental XLS formatting nodes.

The first thing we probably want to do is tell it the name of the sheet. You can see in the above screenshot that I’m calling my sheet “Demo1”, so I’ll add an XLS Sheet Selector node, and configure it:

After that we start doing the fun part :slight_smile:

Let’s set the background colour of any cell containing the tag (label) “header” in the Control Table. We do this by adding an XLS Background Colourizer, and setting the background colour to the cyan colour. We tell it the name of the tag to which this colouring should be applied, by writing the word “header” in the Tag Selection box.

Since every cell in row 1 of the Control Table contains “header”, when this gets applied to the spreadsheet, the column headings in row 1 will all be set to light blue background.

But to do that, we need to somehow apply this formatting to the spreadsheet, and this is where the “finalisation” node called “XLS Formatter (apply)”

You can see that this is configured to read an XLSX file that has been generated with the data, but without the formatting, and then it writes a new XLSX file which is formatted using the information from the Continental XLS Formatting nodes. Also note that a flow variable link is added in my flow between the Excel Writer and the XLS Formatter (apply) node. In this case it is there purely to ensure that the non-formatted xlsx already exists before the attempt is made to apply formatting.

And that is essentially it as a kind of “Hello World” tutorial on formatting a spreadsheet with the Continental nodes.

Adding more formatting is generally a case of adding further nodes in sequence, each feeding to the next, and each receiving the same Control Table, so we can change the background colour of the data rows, and the text colour of the header rows:

One other thing I should have mentioned with the Control Table is that a single cell can be allocated more than one tag, so that it can receive various formatting instructions depending on its position.

Supposing for example, you wanted the Role Access data to be red… Then you might have a Control Table that looked like this:

and you could add additional formatting for the “roleaccess” tag which would output the xlsx like this:

Now, I found that in general, the biggest hurdle to working with the Continental nodes came in understanding (and building) the Control Table. As you can see the control table is relatively simple in basic form. But building it can take a little time, and building it dynamically so that it varies with your data is somewhat more of a challenge than just building a static one like I did in the above example.

The static example shows you what you are aiming for but then to do that with a varying number of columns and rows is where the “simple” becomes “complicated”.

And when I was faced with that part of working with these nodes, I decided that I was going to need to find a way of making “complicated” back into “simple”, or… at least less complicated!

Which is how it is that writing this is the first time in a while that I’ve gone back to basics to explain how these nodes work, and why… I never do it that way! :wink:

Because I wrote a bunch of components to take away the pain and mean I no longer had to really remember how it all worked (until today!).

The first of these components, is the XLS Control Table Auto Tag Generator. A bit of a mouthful but it does what it says on the tin. It automatically generates a whole set of tags in a Control Table based on your data. It essentially builds the tags that I am most commonly going to need, and also allows you to specify the sheet name, so you can do without the XLS Sheet Selector node too.

Notice that the highlighting of the Role Access column data in red was still achievable just using the auto generated tags. This is because for every column it automatically generates tags for that specific column name.

h:Column Name (identifies the cell that is the header for the column)
d:Column Name (identifies all cells that are the data for the column)
c:Column Name (identifies all cells for the column)

Here is the generated control table for the above data:

Along with that, as you can see you automatically get tags identifying the header rows, the data rows, a t:tag which identifies data type, so you can format all t:Local Date columns a particular way, for example.

The data cells in the final row are identified by lastrow tag, and you can also freeze row 1, along with a number of columns (specified in the config for Auto Tag Generator) by using the XLS Sheet Properties tag, telling it to freeze panes at the freezepanes tag.

So I hope that has given you a useful introduction to how the Continental nodes work, but also given you an idea of how to perform simple formatting by making use of my Auto Tag Generator component. You don’t have to use it, and there may still be times you need additional tags, but for general formatting of headers, data and data types, it provides me (and hopefully you) with what is needed.

So now… back to this thread and your need to merge and format cells. Using all of the information provided in this thread so far, with the components for performing merging, and this new post that demonstrates formatting, we can do the following:

The upper branch uses the Auto Tag Generator and you can see that it performs the cell formatting that I’ve just been describing, along with additional formatting for cell horizontal alignment, and formatting of dates.

The lower branch performs the creation of the cell merging tags as described before. I’ve made a couple of modifications to those components for improved performance. Merge tag generation takes a little longer than I would like, and there may be further improvements in future but for the moment it does the job.

You can see that the output “models” (the green square ports) from the upper and lower branches are merged together using the Continental XLS Format Merger, which is useful to know about if you need to add further tags to those generated by the Auto Tag Generator.

Beyond that, hopefully it’s self-explanatory. This is what it produces:

This is the workflow using KNIME AP 5.2
Formatting Excel 1.knwf (677.0 KB)

It turned out to be not quite so quick :wink:

Anyway, you may wish to also read my post from Sep 2022…


Thank you takbb for your help and efforts on this request. Really much appreciated your prompt response!!

I will integrate these steps which you mentioned above into my existing workflow and update you soon for the feedback

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