[Tutor] how do i open picture files without knowing the file name?
I am running this code so I can do some image manipulation with them.
The thing is, I have a lot of pictures to go through, so I can't type the
file names
one by one in the code. However, the order of the files to be processed
doesn't
matter, so getting them in a random fashion is alright!
How do I make the python code open picture files? thanks!
## need to open random png. Any png.
from PIL import Image
## need to load picture so I can process them. Any pictures is fine as
## I need to process every picture in the folder
im = Image.open('1.png')
## do my things...
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Re: [Tutor] how do i open picture files without knowing the file name?
On 16/05/17 19:49, Michael C wrote: > I am running this code so I can do some image manipulation with them. > The thing is, I have a lot of pictures to go through, so I can't type the > file names Do you know the folder where they live? If so os.listdir() will give you a list of filenames. If there are subfolders then os.walk() will traverse them. If you don't understand that come back with more specific questions about what puzzles you and we will expand as necessary. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] how do i open picture files without knowing the file name?
i ll look into it! thx for now! On Tue, May 16, 2017 at 12:51 PM, Alan Gauld via Tutor wrote: > On 16/05/17 19:49, Michael C wrote: > > I am running this code so I can do some image manipulation with them. > > The thing is, I have a lot of pictures to go through, so I can't type the > > file names > > Do you know the folder where they live? > If so os.listdir() will give you a list of filenames. > If there are subfolders then os.walk() will traverse them. > > If you don't understand that come back with more specific > questions about what puzzles you and we will expand > as necessary. > > -- > Alan G > Author of the Learn to Program web site > http://www.alan-g.me.uk/ > http://www.amazon.com/author/alan_gauld > Follow my photo-blog on Flickr at: > http://www.flickr.com/photos/alangauldphotos > > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor > ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] Given a string, call a function of that name
My son (Now 13 years old.) is merrily programming away in Python 3 (Of
course!) and has many projects he is working on. Today he resumed
work on his efforts to create a natural language parser, which he
hopes will enable people to type in commands to a DnD-like game using
natural English. An ambitious project to be sure! He asked me if
there was any way that if he identified a word in the user's input
corresponding to one of his functions or methods, if he could use that
word to run a function of the same name. I said I had done something
once where I used the word as a dictionary key, which was then used to
call the function. After fumbling around a bit I came up with the
following program for him to play around with:
==
#!/usr/bin/env python3
def spam(phrase):
print('spam function said: ', phrase)
def ham(phrase):
print('ham function said: ', phrase)
def eggs(phrase):
print('eggs function said: ', phrase)
def get_input():
function = input('Which do you want: spam, ham or eggs?\n')
phrase = input('\nHow do you want your food to be prepared?\n')
return function, phrase
def check_fcn_input(function):
valid_fcns = ['spam', 'ham', 'eggs']
if function in valid_fcns:
return True
else:
return False
def run_fcn(function, phrase):
fcn_dict = {'spam': spam, 'ham': ham, 'eggs': eggs}
fcn_dict[function](phrase)
def main():
function, phrase = get_input()
while not check_fcn_input(function):
print("You made an invalid food choice! Let's try this again!")
function, phrase = get_input()
run_fcn(function, phrase)
if __name__ == '__main__':
main()
==
This works, but I cannot but help wondering if there is a more direct
approach? Given the above three functions spam(), ham() and eggs(),
and given a string 'ham', what is the quickest, most direct way to run
that function? Or similarly for the other two?
Oh, and I suppose I should ask for a critique of the code as written
for appropriate Python style, proper targeted function use, etc. I am
always eager to learn! However, I did not use doc strings for the
functions or write tests. If I were actually planning on using this
for real, I would have done so.
Hmm. It bothers me that in check_fcn_input() I have a list valid_fcns
and in run_fcn() I have a dictionary fcn_dict. These contain
essentially the same information. Would this be a case for a global
function dictionary (Which I could also use to check for valid
functions.) or perhaps a class which only exists to have this function
dictionary?
TIA!
--
boB
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Re: [Tutor] Given a string, call a function of that name
boB Stepp wrote:
> My son (Now 13 years old.) is merrily programming away in Python 3 (Of
> course!) and has many projects he is working on. Today he resumed
> work on his efforts to create a natural language parser, which he
> hopes will enable people to type in commands to a DnD-like game using
> natural English. An ambitious project to be sure! He asked me if
> there was any way that if he identified a word in the user's input
> corresponding to one of his functions or methods, if he could use that
> word to run a function of the same name. I said I had done something
> once where I used the word as a dictionary key, which was then used to
> call the function. After fumbling around a bit I came up with the
> following program for him to play around with:
>
> ==
> #!/usr/bin/env python3
>
> def spam(phrase):
> print('spam function said: ', phrase)
>
> def ham(phrase):
> print('ham function said: ', phrase)
>
> def eggs(phrase):
> print('eggs function said: ', phrase)
>
> def get_input():
> function = input('Which do you want: spam, ham or eggs?\n')
> phrase = input('\nHow do you want your food to be prepared?\n')
> return function, phrase
>
> def check_fcn_input(function):
> valid_fcns = ['spam', 'ham', 'eggs']
> if function in valid_fcns:
> return True
> else:
> return False
>
> def run_fcn(function, phrase):
> fcn_dict = {'spam': spam, 'ham': ham, 'eggs': eggs}
> fcn_dict[function](phrase)
>
> def main():
> function, phrase = get_input()
> while not check_fcn_input(function):
> print("You made an invalid food choice! Let's try this again!")
> function, phrase = get_input()
> run_fcn(function, phrase)
>
> if __name__ == '__main__':
> main()
> ==
>
> This works, but I cannot but help wondering if there is a more direct
> approach? Given the above three functions spam(), ham() and eggs(),
> and given a string 'ham', what is the quickest, most direct way to run
> that function? Or similarly for the other two?
If you are not bothered about security, getattr(module, function_name)() or
even eval(). But usually the approach you have chosen is preferrable.
> Oh, and I suppose I should ask for a critique of the code as written
> for appropriate Python style, proper targeted function use, etc. I am
> always eager to learn!
> if function in valid_fcns:
> return True
> else:
> return False
should really be spelt
return function in valid_fcns
and personally I wouldn't mind to type the few extra chars to make it
return function in valid_functions
;)
> However, I did not use doc strings for the
> functions or write tests. If I were actually planning on using this
> for real, I would have done so.
>
> Hmm. It bothers me that in check_fcn_input() I have a list valid_fcns
> and in run_fcn() I have a dictionary fcn_dict. These contain
> essentially the same information. Would this be a case for a global
> function dictionary (Which I could also use to check for valid
> functions.) or perhaps a class which only exists to have this function
> dictionary?
A global is indeed better than the duplicate information in your list and
dict. Here's another option, return the function instead of information
about its existence:
def find_function(function):
fcn_dict = {'spam': spam, 'ham': ham, 'eggs': eggs}
return fcn_dict.get(function)
def main():
while True:
function_name, phrase = get_input()
function = find_function(function_name)
if function is not None:
break
print("You made an invalid food choice! Let's try this again!")
function(phrase)
If want to try the class-based approach you can steal from the cmd module:
class Lookup:
prefix = "do_"
def do_spam(self, phrase):
print('spam function said: ', phrase)
def do_ham(self, phrase):
print('ham function said: ', phrase)
def do_eggs(self, phrase):
print('eggs function said: ', phrase)
def known_names(self):
offset = len(self.prefix)
return sorted(
name[offset:] for name in dir(self)
if name.startswith(self.prefix)
)
def get_input(self):
names = self.known_names()
names = ", ".join(names[:-1]) + " or " + names[-1]
function = input('Which do you want: {}?\n'.format(names))
phrase = input('\nHow do you want your food to be prepared?\n')
return function, phrase
def find_function(self, function):
return getattr(self, self.prefix + function, None)
def one_cmd(self):
while True:
function_name, phrase = self.get_input()
function = self.find_function(function_name)
if function is not None:
break
print("
