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knime-mpicbg / knime-scripting

knime-scripting includes scripting extensions for KNIME to integrate R, Matlab, Python and Groovy scripts. These extensions include a collection of nodes to develop and deploy templates in the respective languages.
https://github.com/knime-mpicbg/knime-scripting/wiki
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Python with pandas: problems to transfer table with missing values #55

Closed niederle closed 3 years ago

niederle commented 9 years ago

pyhton nodes fail to transfer tables with missing values for integer columns. for string columns 'nan' is returned instead of a missing value. double columns are fine.

niederle commented 9 years ago

further information here: http://pandas.pydata.org/pandas-docs/stable/gotchas.html#support-for-integer-na

niederle commented 9 years ago

the current implementation needs to be changed to enable correct handling for missing values on string columns. CSVReader and CSVWriter (opencsv) do not support quotes for non-numeric values only. instead one might watn to use the CSVReader / -Writer from knime. But then the input CSV cannot include column types anymore...