If statement syntax error

[OkieWolf]

@mcriley821
It’s getting to the else statement because it’s inputting the text “Enter All Fields”. It just won’t change the color.

[mcriley821]

@OkieWolf

Scratch that, sorry. I was thinking of a label. A textField doesn’t really have a background. It’s background is behind the white layer. What you could do instead is make a red border.

If you really want the whole thing red, I can write a small bit of code with objc_util

[cvp]

@OkieWolf already done here

[mikael]

@OkieWolf, you hit one of known quirks. You can set bordered to False, after which background_color works. Or if that appearance does not work for you, @cvp’s solution can be turned into a helper function that you can call with just 'red':

def textfield_background(tf, color):
    import objc_util
    tfo = tf.objc_instance.textField()
    tfo.backgroundColor = objc_util.UIColor.colorWithRed_green_blue_alpha_(
        *ui.parse_color(color))

[OkieWolf]

What about text color? Can I change the textfield text color to red?

[cvp]

@OkieWolf .text_color = 'red'

[OkieWolf]

This post is deleted!

[OkieWolf]

Here’s the completed button using the Pythagorean Theorem to calculate. It looks to see which of the three textfields is blank then calculates what it should be based on the input of the other two.

def button3_tapped(sender):
	if (v['textfield3'].text)!="" and (v['textfield4'].text)!="":
		hyp = float(v['textfield3'].text)
		sht = float(v['textfield4'].text)
		hyp = pow(hyp,2)
		sht = pow(sht,2)
		lng = math.sqrt(hyp - sht)
		v['textfield5'].text_color = 'green'
		v['textfield5'].text = str(lng)
	elif (v['textfield4'].text)!="" and (v['textfield5'].text)!="":
		sht = float(v['textfield4'].text)
		lng = float(v['textfield5'].text)
		sht = pow(sht,2)
		lng = pow(lng,2)
		hyp = math.sqrt(sht + lng)
		v['textfield3'].text_color = 'green'
		v['textfield3'].text = str(hyp)
	elif (v['textfield3'].text)!="" and (v['textfield5'].text)!="":
		hyp = float(v['textfield3'].text)
		lng = float(v['textfield5'].text)
		hyp = pow(hyp,2)
		lng = pow(lng,2)
		sht = math.sqrt(hyp - lng)
		v['textfield4'].text_color = 'green'
		v['textfield4'].text = str(sht)
	else:
		v['textfield5'].text_color = 'red'
		v['textfield5'].text = 'ENTER ALL FIELDS' ```

[ccc]

The logic is easier to follow if field names describe their content.

def button3_tapped(sender):
    hypotenuse = float(v['hypotenuse'].text or 0)
    short = float(v['short'].text or 0)
    long = float(v['long'].text or 0)
    if len([x for x in (hypotenuse, short, long) if x]) != 2:
        v['long'].text = "Enter floats in 2 fields"
        v['long'].text_color = 'red'
        return
    if hypotenuse:
        if short and not long:
            v['long'].text = str(math.sqrt(hypotenuse ** 2 - short ** 2))
            v['long'].text_color = 'green'
        elif long and not short:
            v['short'].txt = str(math.sqrt(hypotenuse ** 2 - long ** 2))
            v['short'].text_color = 'green'
    else:
        v['hypotenuse'].text = str(math.sqrt(short ** 2 + long ** 2))
        v['hypotenuse'].text_color = 'green'

[OkieWolf]

@ccc
Could you please explain how this works in more detail?
I realize you’ve renamed textfields but I’m not exactly understanding how the code is working. I’m mainly not understanding what’s happening with the or 0 and then the if len([x for x in (hypotenuse, short, long) if x]) != 2

hypotenuse = float(v['hypotenuse'].text or 0)
    short = float(v['short'].text or 0)
    long = float(v['long'].text or 0)
    if len([x for x in (hypotenuse, short, long) if x]) != 2: ```

[mcriley821]

@OkieWolf

hypotenuse = float(v['hypotenuse'].text or 0)
    short = float(v['short'].text or 0)
    long = float(v['long'].text or 0)
    if len([x for x in (hypotenuse, short, long) if x]) != 2: ```

v['short'].text or 0 will choose 0 if the text is "". You won’t hit an exception for a blank textfield. You will get an error if the text is alphabetical though.

(hypotenuse,short,long) is a tuple and [x for x in (hypotenuse,short,long) if x] is a list comprehension that steps through the tuple
and makes a list of the values that exist. Then if the length of that list isn’t 2, then you don’t have a correct input

[OkieWolf]

I need to probably rewrite the whole program because I’ve added more error trapping and a fourth textfield. It has increased complexity quite a bit, at least for me. It now cycles through all four textfields, find any two valid fields, decides whether to use Pythagorean Theorem or plain trig, and checks all for errors. One error in particular is that it is possible with the answers to have the short side of the triangle be longer than the long side. Obviously this can never happen so it’s now trapped and alerts the user.
Below is what I now have. I realize my code is a longer than it needs to be and fairly cumbersome at this point but I’m just learning Python and intend to try to rewrite it in a better and more efficient way.

def button3_tapped(sender):
	if (v['textfield3'].text)!="" and (v['textfield4'].text)!="":
		v['label7'].background_color = 'white'
		v['label7'].text_color = 'white'
		v['label7'].text = ''
		hyp = float(v['textfield3'].text)
		sht = float(v['textfield4'].text)
		hypa = hyp
		shta = sht
		hyp = pow(hyp,2)
		sht = pow(sht,2)
		lng = math.sqrt(hyp - sht)
		lnga = lng
		ang = math.asin(shta/hypa)
		ang = math.degrees(ang)
		v['textfield5'].text_color = 'green'
		v['textfield5'].text = str(lng)
		v['textfield6'].text_color = 'green'
		v['textfield6'].text = str(ang)
		shtb = float(v['textfield4'].text)
		lngb = float(v['textfield5'].text)
		if shtb > lngb:
			v['label7'].background_color = 'red'
			v['label7'].text_color = 'white'
			v['label7'].text = 'ERROR. Short side cannot be longer than long side.'
	elif (v['textfield4'].text)!="" and (v['textfield5'].text)!="":
		v['label7'].background_color = 'white'
		v['label7'].text_color = 'white'
		v['label7'].text = ''
		sht = float(v['textfield4'].text)
		shta = sht
		lng = float(v['textfield5'].text)
		lnga = lng
		sht = pow(sht,2)
		lng = pow(lng,2)
		hyp = math.sqrt(sht + lng)
		hypa = hyp
		ang = math.asin(shta/hypa)
		ang = math.degrees(ang)
		v['textfield3'].text_color = 'green'
		v['textfield3'].text = str(hyp)
		v['textfield6'].text_color = 'green'
		v['textfield6'].text = str(ang)
		shtb = float(v['textfield4'].text)
		lngb = float(v['textfield5'].text)
		if shtb > lngb:
			v['label7'].background_color = 'red'
			v['label7'].text_color = 'white'
			v['label7'].text = 'ERROR. Short side cannot be longer than long side.'
	elif (v['textfield3'].text)!="" and (v['textfield5'].text)!="":
		v['label7'].background_color = 'white'
		v['label7'].text_color = 'white'
		v['label7'].text = ''
		hyp = float(v['textfield3'].text)
		hypa = hyp
		lng = float(v['textfield5'].text)
		lnga = lng
		hyp = pow(hyp,2)
		lng = pow(lng,2)
		sht = math.sqrt(hyp - lng)
		shta = sht
		ang = math.asin(shta/hypa)
		ang = math.degrees(ang)
		v['textfield4'].text_color = 'green'
		v['textfield4'].text = str(sht)
		v['textfield6'].text_color = 'green'
		v['textfield6'].text = str(ang)
		shtb = float(v['textfield4'].text)
		lngb = float(v['textfield5'].text)
		if shtb > lngb:
			v['label7'].background_color = 'red'
			v['label7'].text_color = 'white'
			v['label7'].text = 'ERROR. Short side cannot be longer than long side.'
	elif (v['textfield3'].text)!="" and (v['textfield6'].text)!="":
		v['label7'].background_color = 'white'
		v['label7'].text_color = 'white'
		v['label7'].text = ''
		hyp = float(v['textfield3'].text)
		ang = float(v['textfield6'].text)
		ang = math.radians(ang)
		hypa = hyp
		sht = hyp * math.sin(ang)
		shta = sht
		hypc = pow(hyp,2)
		shtc = pow(sht,2)
		lng = math.sqrt(hypc - shtc)
		lnga = lng
		v['textfield5'].text_color = 'green'
		v['textfield5'].text = str(lng)
		v['textfield4'].text_color = 'green'
		v['textfield4'].text = str(sht)
		shtb = float(v['textfield4'].text)
		lngb = float(v['textfield5'].text)
		if shtb > lngb:
			v['label7'].background_color = 'red'
			v['label7'].text_color = 'white'
			v['label7'].text = 'ERROR. Short side cannot be longer than long side.'
	elif (v['textfield4'].text)!="" and (v['textfield6'].text)!="":
		v['label7'].background_color = 'white'
		v['label7'].text_color = 'white'
		v['label7'].text = ''
		sht = float(v['textfield4'].text)
		ang = float(v['textfield6'].text)
		ang = math.radians(ang)
		shta = sht
		hyp = sht / math.sin(ang)
		hypa = hyp
		hypc = pow(hyp,2)
		shtc = pow(sht,2)
		lng = math.sqrt(hypc - shtc)
		shta = sht
		v['textfield5'].text_color = 'green'
		v['textfield5'].text = str(lng)
		v['textfield3'].text_color = 'green'
		v['textfield3'].text = str(hyp)
		shtb = float(v['textfield4'].text)
		lngb = float(v['textfield5'].text)
		if shtb > lngb:
			v['label7'].background_color = 'red'
			v['label7'].text_color = 'white'
			v['label7'].text = 'ERROR. Short side cannot be longer than long side.'
	elif (v['textfield5'].text)!="" and (v['textfield6'].text)!="":
		v['label7'].background_color = 'white'
		v['label7'].text_color = 'white'
		v['label7'].text = ''
		lng = float(v['textfield5'].text)
		ang = float(v['textfield6'].text)
		ang = math.radians(ang)
		lnga = lng
		hyp = lng / math.cos(ang)
		hypa = hyp
		hypc = pow(hyp,2)
		lngc = pow(lng,2)
		sht = math.sqrt(hypc - lngc)
		shta = sht
		v['textfield4'].text_color = 'green'
		v['textfield4'].text = str(sht)
		v['textfield3'].text_color = 'green'
		v['textfield3'].text = str(hyp)
		shtb = float(v['textfield4'].text)
		lngb = float(v['textfield5'].text)
		if shtb > lngb:
			v['label7'].background_color = 'red'
			v['label7'].text_color = 'white'
			v['label7'].text = 'ERROR. Short side cannot be longer than long side.'
	else:
		v['label7'].background_color = 'red'
		v['label7'].text_color = 'white'
		v['label7'].text = 'ERROR' ```

[OkieWolf]

If you import math why do you still have to say math.sqrt and math.cos?
But then other things like pow don’t have to say math.pow.

[ccc]

pow() is a Python builtin. https://docs.python.org/3/library/functions.html

You can also say from math import cos, sin, tan to use the single word functions.

[OkieWolf]

This post is deleted!

[OkieWolf]

@ccc

I’m attempting to rewrite my code to be more efficient and am utilizing a couple of code snippets that a couple of you have supplied. However, in the below code I noticed that the output is 0.0 if both inputs happen to be the same number. I’m not understanding why.

def button3_tapped(sender):
	hypotenuse = float(v['hypotenuse'].text or 0)
	short = float(v['short'].text or 0)
	long = float(v['long'].text or 0)
	if len([x for x in (hypotenuse, short, long) if x]) != 2:
		v['mess'].text = "Enter two fields"
		v['mess'].background_color = 'red'
		v['mess'].text_color = 'white'
		return
	if hypotenuse:
		if short and not long:
			v['long'].text = str(math.sqrt(hypotenuse ** 2 - short ** 2))
			v['long'].text_color = 'green'
		elif long and not short:
			v['short'].text = str(math.sqrt(hypotenuse ** 2 - long ** 2))
			v['short'].text_color = 'green'
	else:
		v['hypotenuse'].text = str(math.sqrt(short ** 2 + long ** 2))
		v['hypotenuse'].text_color = 'green' ```

[ccc]

if both inputs happen to be the same number

if hypotenuse:
    if short:
        The rules of math say that the hypotenuse must be greater than short.
    else
        The rules of math say that the hypotenuse must be greater than long.
else:
    short could be the same number as long  # <-- this is the only instance where both inputs could be the same number

if hypotenuse and (short >= hypotenuse or long >= hypotenuse):
    raise ValueError("Not allowed by the rules of math.")

[OkieWolf]

Agreed. It works fine if short and long are the same number, which equals 45 degrees.

[OkieWolf]

Here’s what I came up with. It’s much shorter and easier to understand and I GREATLY appreciate all the help and patience.
This version does all the other one did plus more. This version will calculate the other side and angle based on two sides input and can now calculate any side of the triangle based on angle and any one of the three sides.

def button3_tapped(sender):
	hypotenuse = float(v['hypotenuse'].text or 0)
	short = float(v['short'].text or 0)
	long = float(v['long'].text or 0)
	angle = float(v['angle'].text or 0)
	if len([x for x in (hypotenuse, short, long, angle) if x]) != 2:
		v['mess'].text = "Enter two fields"
		v['mess'].background_color = 'red'
		v['mess'].text_color = 'white'
		return
	if hypotenuse and not angle:
		if short and not long:
			v['long'].text = str(math.sqrt(hypotenuse ** 2 - short ** 2))
			v['long'].text_color = 'green'
			v['angle'].text = str(math.degrees(math.asin(short / hypotenuse)))
			v['angle'].text_color = 'green'
		elif long and not short:
			v['short'].text = str(math.sqrt(hypotenuse ** 2 - long ** 2))
			v['short'].text_color = 'green'
			v['angle'].text = str(math.degrees(math.acos(long / hypotenuse)))
			v['angle'].text_color = 'green'
	else:
		if not angle:
			v['hypotenuse'].text = str(math.sqrt(short ** 2 + long ** 2))
			v['hypotenuse'].text_color = 'green'
			v['angle'].text = str(math.degrees(math.atan(short / long)))
			v['angle'].text_color = 'green'
		
	if angle:
		angle = math.radians(angle)
		if short and not long and not hypotenuse:
			v['hypotenuse'].text = str(short / (math.sin(angle)))
			v['hypotenuse'].text_color = 'green'
			v['long'].text = str(short / (math.tan(angle)))
			v['long'].text_color = 'green'
		elif long and not short and not hypotenuse:
			v['hypotenuse'].text = str(long / (math.cos(angle)))
			v['hypotenuse'].text_color = 'green'
			v['short'].text = str(long * (math.tan(angle)))
			v['short'].text_color = 'green'
		elif angle and hypotenuse and not long and not short:
			v['short'].text = str(hypotenuse * (math.sin(angle)))
			v['short'].text_color = 'green'
			v['long'].text = str(hypotenuse * (math.cos(angle)))
			v['long'].text_color = 'green' 

[ccc]

Please put the trailing three backticks on a line all by themselves.