Handling "Double Quotes" on string joining function

KNIME Analytics Platform
#1

Hello all,

I am working with join expressions under the ‘String Manipulation’ node.

I would like to be able to concatenate strings, however, if one of the columns’ value its been used to concatenate has spaces, I must use “double quotes” to handle that specific case.

For example:

color carName
black Jaguar
blue BMW
white Jeep Grand Cherokee

Output:

black Jaguar
blue BMW
white “Jeep Grand Cherokee”

“I understand about the difference between brands and names of vehicles, but you get the point…”

Handling the space:

I thought of using the ‘Rule Engine’ node but can’t figure out if in it has an expression to handle IF FOUND like in Excel we have, ISNUMBER(SEARCH) . I have tried:

< " " IN $carName" => TRUE > then I append a column (spaceFound) w a true or false for later handling by the double quote function

also tried:
" " MATCHES $carName" => TRUE

both do not work

concatenating w join:

I am concatenating with join as:

join($color$, < if value is TRUE on (spaceFound) col , then > DOUBLE QUOTES,$carName$,DOUBLE QUOTES ) [adding the double quotes to the beginning and end of the value of $carName"]

Thank you all,
J.

#2

Hi @jarviscampbell

Before jumping towards a solution, just a double check:
Is your desired output only to quote the carName column whenever it contains a space like in the Output:?

Because in your pseudo code I see you doing join($color$, so I’m assuming the desired output is actually one string saying white “Jeep Grand Cherokee”

Thanks

#3

Hi @ArjenEX,

No, it will output regardless, but when there’s a space, double quotes should be added.

Thanks for checking.
J.

#4

Sorry, I have adjusted the output as it should be.

Just need to join the strings from both columns.

#5

Allright @jarviscampbell

My suggestion would be to use one the most powerful tools available for strings, the Column Expression.
Your desired output is achievable through:

if (contains(column("carName")," ") == true) {
    column("color") + " \"" + column("carName") + "\""
} else {
    column("color") + " " + column("carName")
}

image
image1167×712 27.4 KB

What it does:

  • It checks if the carName contains a space, resulting in true or false.
  • If true, create a string by concatenating: the color, a quote, the carName and another quote. Key here is that you have to escape the quote since it’s a special character. This is done with the backslash.
  • If false, concat only the color and carName with a space in between.

See WF:
Handling “Double Quotes” on string joining function.knwf (12.8 KB)

Hope this helps!

3 Likes
#6

Outstanding @ArjenEX , Beautiful brain of yours. That’s exactly what I was looking for.

Again, I appreciate you.