String to Number

KNIME Analytics Platform
1

Hi All,

    Good day.

    Have a problem that really I am banging my head against the wall and don't know why is happening.  I have a file with columns as strings and I am using Manipulation -> Column -> Convert & Replace -> String to Number, in order to make my string values as numbers -because I want to use neural networks for prediction-  and when i use and execute it, there is not parsing at all and i do not know why, it is a  normal string.

     Would appreciate some help on this, thank you all in advance. :D

Mauricio

 

WARN  String To Number     2:14       Values in 4599 cells could not be parsed, first error: '2015/06' (RowKey: Row0, Position: 0)
WARN  String To Number     2:14       Problems occurred, see Console messages.

2

Hi there,

this is very obvious in the log: 2015/06 is not a number ;-)

You could split up the string into a year and month component and then parse both individually. Or parse it as a date type using "String to date" node.

Best,
Philipp

3

Actually is not a date, it is a string. but also happnes with another strings such as "Component".

Thank you

Mauricio

4

Hi Mauricio,

sorry if I misunderstood, but then what's your intention for converting those values to numbers? The "String to Number" merely performs a type conversion (string "1" -> number "1"), it's not intended to convert values such as "alpha" to a number representation.

As you're mentioning neural nets, are you probably looking for an encoding of nominal values, such as one-hot?

Best,
Philipp

5

Yes Philipp, you are correct.  What i want to do is make all the strings on my data to be encoded as numbers, because neural nets only work with numbers.  For instance, if i have a column named "Component" with values

Savings costs

Expenses made

Reimbursement pending

Expenses made

then make them

345

901

344

901

get my point?.  If so, what would you suggest to use?

Many thanks in advance.

Mauricio Concha

 

 

 

6

Hi Mauricio,

Three possibilities:

- import a correspondance list between the strings and your numeric codes and merge it with your table;

- create such a list à la mano using Table creator if you want some sort of interface;

- use Rule Engine to do the above à la mano;

- use One To Many node to go the dummy variable route instead.

Probably there are many more possibilities.

Cheers

George

7

Thank you all!! :D

 

Mauricio Concha