Converting an RGB color tuple to a hexidecimal string

I'm truly surprised no one suggested this approach:

For Python 2 and 3:

'#' + ''.join('{:02X}'.format(i) for i in colortuple)

Python 3.6+:

'#' + ''.join(f'{i:02X}' for i in colortuple)

As a function:

def hextriplet(colortuple):
    return '#' + ''.join(f'{i:02X}' for i in colortuple)

color = (0, 128, 64)
print(hextriplet(color))

#008040

you can use lambda and f-strings(available in python 3.6+)

rgb2hex = lambda r,g,b: f"#{r:02x}{g:02x}{b:02x}"
hex2rgb = lambda hx: (int(hx[0:2],16),int(hx[2:4],16),int(hx[4:6],16))

usage

rgb2hex(r,g,b) #output = #hexcolor hex2rgb("#hex") #output = (r,g,b) hexcolor must be in #hex format

In Python 3.6, you can use f-strings to make this cleaner:

rgb = (0,128, 64)
f'#{rgb[0]:02x}{rgb[1]:02x}{rgb[2]:02x}'

Of course you can put that into a function, and as a bonus, values get rounded and converted to int:

def rgb2hex(r,g,b):
    return f'#{int(round(r)):02x}{int(round(g)):02x}{int(round(b)):02x}'

rgb2hex(*rgb)

Here is a more complete function for handling situations in which you may have RGB values in the range [0,1] or the range [0,255].

def RGBtoHex(vals, rgbtype=1):
  """Converts RGB values in a variety of formats to Hex values.

     @param  vals     An RGB/RGBA tuple
     @param  rgbtype  Valid valus are:
                          1 - Inputs are in the range 0 to 1
                        256 - Inputs are in the range 0 to 255

     @return A hex string in the form '#RRGGBB' or '#RRGGBBAA'
"""

  if len(vals)!=3 and len(vals)!=4:
    raise Exception("RGB or RGBA inputs to RGBtoHex must have three or four elements!")
  if rgbtype!=1 and rgbtype!=256:
    raise Exception("rgbtype must be 1 or 256!")

  #Convert from 0-1 RGB/RGBA to 0-255 RGB/RGBA
  if rgbtype==1:
    vals = [255*x for x in vals]

  #Ensure values are rounded integers, convert to hex, and concatenate
  return '#' + ''.join(['{:02X}'.format(int(round(x))) for x in vals])

print(RGBtoHex((0.1,0.3,  1)))
print(RGBtoHex((0.8,0.5,  0)))
print(RGBtoHex((  3, 20,147), rgbtype=256))
print(RGBtoHex((  3, 20,147,43), rgbtype=256))

You can also use bit wise operators which is pretty efficient, even though I doubt you'd be worried about efficiency with something like this. It's also relatively clean. Note it doesn't clamp or check bounds. This has been supported since at least Python 2.7.17.

hex(r << 16 | g << 8 | b)

And to change it so it starts with a # you can do:

"#" + hex(243 << 16 | 103 << 8 | 67)[2:]

There is a package called webcolors. https://github.com/ubernostrum/webcolors

It has a method webcolors.rgb_to_hex

>>> import webcolors
>>> webcolors.rgb_to_hex((12,232,23))
'#0ce817'

''.join('%02x'%i for i in input)

can be used for hex conversion from int number

If typing the formatting string three times seems a bit verbose...

The combination of bit shifts and an f-string will do the job nicely:

# Example setup.
>>> r, g, b = 0, 0, 195

# Create the hex string.
>>> f'#{r << 16 | g << 8 | b:06x}'
'#0000c3'

This also illustrates a method by which 'leading' zero bits are not dropped, if either the red or green channels are zero.

Use this line '#%02X%02X%02X' % (r,g,b)