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def changeColor(picture, amount, number):
for p in getPixels(picture):
if number == 1:
setRed(p, getRed(p)*(amount + 1))
if number == 2:
setGreen(p, getGreen(p)*(amount + 1))
if number == 3:
setBlue(p, getBlue(p)* (amount + 1))
| This code looks pretty good to me! Ashley Coker |
def changeColor(picture, amount, channel)
for p in getPixels(picture)
red=getRed(p)
green=getGreen(p)
blue=getBlue(p)
if channel==1:
setRed(p, red*(1+amount))
if channel==2:
setGreen(p, green*(1+amount))
if channel==3:
setBlue(p, blue(1+amount))
| If you don't do red=getRed(p), green=getGreen(p), blue=getBlue(p), then you must change the other times you use the variables "red","green", and "blue". It is just easier to read and understand (and debug) if you do it. But to answer your question, no, it is not necessary. Ashley Coker |
def changeColor(picture, value, number):
for p in getPixels(picture):
red=getRed(p)
setRed(p, -.5, 1)
green=getGreen(p)
setRed(p, .8, 2)
blue=getBlue(p)
setBlue(p, .5, 3)
I know I am missing a lot here, but for starters, what is the best way to tell the computer that R, G, & B equal 1, 2, & 3?
| (see answer below) Ashley Coker |
def changeColor(picture, value, number):
for p in getPixels(picture):
red=getRed(p)
setRed(p, -.5, 1)
green=getGreen(p)
setRed(p, .8, 2)
blue=getBlue(p)
setBlue(p, .5, 3)
| what about some if statements? Like "if number == 1:" Ashley Coker |
def changeColor(picture,amount,number):
for p in getPixels(picture):
if number == 1:
setRed(p,getRed(p)*amount)
if number == 2:
setGreen(p,getGreen(p)*amount)
if number == 3:
setBlue(p,getBlue(p)*amount)
| Look at this again. The inputs you will be using are between -.99 and .99. However, if the amount is .50, you want to increase the value by 50%–your code will make the value 50% of its original value. Something needs to be added so that will work correctly, but otherwise you have the right idea... Summer McWilliams |
| Yes you would need to multiply by the 'amount' plus 1. Look at Summer's answer right above your question because she explains it very well there. Ashley Coker |
| Remember, too, that you want your programs to work for ANY input amounts (between -.99 and .99). If you put in explicitly numbers like .5, then it will only work for those values. Mark Guzdial |
def changeColor(picture,amount,number):
for p in getPixels(picture):
if number == 1:
setRed(p,getRed(p)*amount + getRed(p))
if number == 2:
setGreen(p,getGreen(p)*amount + getGreen(p))
if number == 3:
setBlue(p,getBlue(p)*amount + getBlue(p))
| Rae, your program is actually equivalent to the other ones. Work out the math: getRed(p)*(1+amount) is the same (algebraically) as getRed(p)+(getRed(p)*amount). Mark Guzdial |
| Try working out the math. Mark Guzdial |
| We use single equal signs "=" when we're doing assignments. We do double equal signs "==" when testing to see if one value is equal to another. Typically, you'll use only "==" in IF statements. If you see someplace in the book where we're using single "=" in an IF statement, please let me know! That's a bug! Mark Guzdial |
| Because if you want to decrease by 10%, the input would be negative 10% (-.10), so when you add 1, it becomes 0.9, or decreased by 10%. Brienne Thorusen |
| Like Brienne said. Remember that the input is going to be negative for decreasing and positive for increasing amounts. If you multiply getRed (for example) by a negative value (like -.10), you're going to get a negative value – you can't set red to a negative value. What you really want to do is multiply getRed by a positive value that will give you right result. To decrease by 10%, you actually want to multiply by .90. How do you get to .90 when you have an input of -.10? Add one to the input. That generally works for all the positive/negative values to get the increment/discount. Mark Guzdial |
| JES doesn't know anything about what the value "1" means. There is no meaning other than what your program does with the values. Mark Guzdial |