String to Number node problem and Flow variables option confusion

Hello everyone,

                          I am working on latest knime version 2.5.1. I have dataset which contains fields of string type. I want this string dataset to be converted into numerical dataset. So i used String to Number node. But string values are not getting converted instead giving blanks at that place and showing warnings  like values are not parsed. How to make String to number node execute properly?. Is there anyother way in knime to convert the String dataset into numerical dataset?. Please Guide me in this

                          One more doubt in knime latest version is, for every node there is flow variable tab is there, within that so many options are available. i Tried to understand it and searched for that but unable to find. So please let me know about it.

                                     Thanking you


If any cell contains text, then this will be returned as a blank cell, as text cannot exist in numerical format. If the cell contains a number as well as text, then you will need to first remove the text, this can be done with String Replacer if its the same text in each cell (i.e. if your cells say "100 apples" and "52 apples" etc, then replace "apple" for an empty string with String Replacer node), or you could use the Cell Splitter nodes too.

For the flow variables, this would require a lengthy explanation. The flow variable tab is used inconjunction with the flow control/Loop Support and flow control/variables set of nodes. Your best bet is to have a play with the example workflows in the "Server Workflow Projects" window at the bottom right. Variables are a very powerful feature of KNIME, but also can be complex to understand at the beginning, its worth the time investment to learn about them. The best simple explanation I can offer is that you can take cell contents and convert them into a variable with a specific name, this variable is then available in all subsequent nodes, accessible via the flow control tab, and this allows you to enter values or text into the configuration of a node via a flow variable, rather than manually entering text in the subsequent nodes. This is useful when the value you want in the node configuration changes, which would be painful to do manually, consequently, through use of variables, this all becomes simple and automated. And if you want the variable to change many times in the workflow, you can do this, and the workflow can loop round back to the beginning and process the data again with the next variable until all the variables have been used.

Hope this helps and gives you a taster of what variables do.