Question: error with champ.load
gravatar for o.giannakopoulou
23 months ago by
o.giannakopoulou0 wrote:


I'm using the champ.load to read and filter my data and it works well. However when I want to proceed with the champ.QC I receive an error because the column "Sample_Group" in the csv file provided is empty. 

So I tried to add the information of that column ("first" or "second") and use the modified csv file to load the idat files. However at that point I'm getting the following error:

"Error in champ.import(directory, arraytype = arraytype) : Error Match between pd file and Green Channel IDAT file."

I went through the pipeline to check how ChAMP imports the data but I did not manage to pick which is the mistake. I know It would be great if you could help so that I can include this information and proceed with champ.QC. 

Thank you,

Olga Giannakopoulou 


champ • 1.1k views
ADD COMMENTlink modified 23 months ago by Yuan Tian120 • written 23 months ago by o.giannakopoulou0
Answer: error with champ.load
gravatar for Yuan Tian
23 months ago by
Yuan Tian120
University College London
Yuan Tian120 wrote:

Hello Olga:

Firstly, champ.QC() failed because of lacing of Sample_Group column, which could because your csv file does not contain Sample_Group. That's OK because different research have different column name on most interested covariates. In champ.QC() there should be a parameter called "pheno", you just need to change it as myLoad$pd$your_phenotype, then it should be good. 

Another question about loading is:

Based on my experience, the most possible error is because you used Excel to open original CSV file, then added information on that, then same it as CSV again. By doing this, original Sentrix_ID (a very long number) could be changed. I guess it's some format problem with Excel.

Than after you modify the file, ChAMP will load your csv file, then get Sentrix_ID and Sentrix_Position, and map them to IDAT data, since Sentrix_ID has changed, no IDAT file would be matched.

I think this is the most possible reason. Please check you modified CSV file and original one, focus on the Sentrix_ID column.

If not this reason, I would check closer into code.


Yuan Tian

ADD COMMENTlink written 23 months ago by Yuan Tian120

Indeed the problem was with editing the excel file. As you guessed, when I was saving the csv file, after adding Sample_Group information, the Sentrix_ID was changing. I managed to make it work after making sure that Sentrix_ID was in "Numeric" format each time. 

Thank you again for the help

Best wishes,


ADD REPLYlink written 23 months ago by o.giannakopoulou0

Firstly i'm a beginner. i have the same problem when I use champ.load("Error Match between pd file and Green Channel IDAT file"). my sample_ sheet is edited using excel by myself. but i don't know how to make sure that Sentrix_ID was in "Numeric" format.

thank you, may

ADD REPLYlink written 6 months ago by mayue88660
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