And if statements in NetLogo

Question

I am trying to create a simulation of bees spreading pollen, I was hoping to make it so when a bee visits a flower it changes the colour to blue and the turtle 'bee' gets given a pollen value of +1, then when it has a pollen value of +3 and visits a flower the colour changes to green.

I have tried multiple methods to go about this, if there was an and if statement that would be useful eg

to pollenate 
ask turtles [
if pollen > 3
and if pcolor = yellow or blue [ 
set pcolor white
set pollen pollen - 3
]
]
end 

I'm not sure if and statements exist though.

so I tried with when the turtles have a pollen count of higher than 3 they change color, then tried the code below but keep getting an error message.

to pollenate
ask turtles with [ color = white ] [
if pcolor = blue
[set pcolor = green
set pollen pollen -3
]
]
end

I keep getting the error 'Set expected 2 inputs'

any help on either approach would be greatly appreciated, or if i'm doing the whole thing wrong please let me know haha.

Answer 1

Here's the answers to your two questions.

(1) "and if " can be accomplished by using a logical AND in the test. I HAD to use parentheses around the color tests that were connected by OR and then AND that to the pollen > 3 test. As in mathematics, the inner parentheses are evaluated first. I prefer to use parentheses around all logical tests Like ( pollen > 3) -- it's not required but I find it much easier to read.

to pollenate 
ask turtles [
    if (pollen > 3) and ((pcolor  = yellow) or (pcolor = blue))
            [ 
               set pcolor white
               set pollen pollen - 3
           ]
]
end 

you could use a test for pcolor being found in a list of colors too, like this;

to pollenate 
ask turtles [
    if (pollen > 3) and (member? pcolor [yellow blue] )
            [ 
               set pcolor white
               set pollen pollen - 3
           ]
]
end 

As to your second question, the working version would be

o pollenate
ask turtles with [ color = white ] [
if pcolor = blue
[set pcolor = green
set pollen pollen - 3
]
]
end

Didn't see the difference? I put a space on both sides of the minus sign, otherwise Netlogo sees three parameters: pollen, pollen, and -3 instead of two you want,namely pollen and (pollen - 3).