Python

List convert to string

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Join Date: Sep 2009

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Felicidas

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List convert to string

Nov 6th, 2009

Hi everyone,

hope someone can give me some hints about my problem.
I write a program that read users input through command line(args).
This input i put it as a list. User type number that they want separated with comma

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
--number 1,2,3,4
--number 1,2,3,4

The next process is to read the file and and use those numbers above to determine which part of the file will be outputted.
The file is a 2 row file which 1st row represented the user's input

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
 20
 56
 42
 53
 90
 33
 20
 56
 42
 53
 90
 33

So based on the user input, the system should display

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
 20
 56
 42
 53
 20
 56
 42
 53

My problem is because the user input i put as lists, python complains that it should be integer.
Can anyone gives me a hint? still stuck in this problem

Many thanks before
feli

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Join Date: Jul 2008

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jlm699

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Knows where his Towel is

Nov 6th, 2009

Here's some examples of converting between strings, lists, lists of strings, and ints using list , str and int :

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
>>> usr_inp = '123456'
>>> usr_inp2 = '1,2,3,4,5,6'
>>> list(usr_inp)
['1', '2', '3', '4', '5', '6']
>>> usr_inp2.split(',')
['1', '2', '3', '4', '5', '6']
>>> list(usr_inp)[4]
'5'
>>> int(list(usr_inp)[4])
5
>>> str(int(list(usr_inp)[4]))
'5'
>>>
>>> usr_inp = '123456'
>>> usr_inp2 = '1,2,3,4,5,6'
>>> list(usr_inp)
['1', '2', '3', '4', '5', '6']
>>> usr_inp2.split(',')
['1', '2', '3', '4', '5', '6']
>>> list(usr_inp)[4]
'5'
>>> int(list(usr_inp)[4])
5
>>> str(int(list(usr_inp)[4]))
'5'
>>>

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Join Date: Sep 2009

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Felicidas

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Nov 6th, 2009

Hi..
thanks for the help.
I think my explanation is not clear before.
My problem is actually how to filter the input list against the int data.

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
user_input = 1 2 3 # as list
int_data = 1 2 3 4 5 # as int
# How to loop output only the  int_data that has the same value with user_input
# something like :
for user_input in int_data:
    print int_data  #The output should be : 1 2 3
user_input = 1 2 3 # as list
int_data = 1 2 3 4 5 # as int
# How to loop output only the  int_data that has the same value with user_input
# something like :
for user_input in int_data:
    print int_data  #The output should be : 1 2 3

The error that i got is

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
TypeError: int() argument must be a string or a number, not 'list'
TypeError: int() argument must be a string or a number, not 'list'

because i try to filter int with lists, which is not allowed i guess.
Does someone have idea? Or instead of list, i should use array?
many thanks again

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masterofpuppets masterofpuppets is offline

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Nov 6th, 2009

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Help with Code Tags

Python Syntax (Toggle Plain Text)
user_input = 1 2 3 # as list
int_data = 1 2 3 4 5 # as int
# How to loop output only the  int_data that has the same value with user_input
# something like :
for user_input in int_data:
    print int_data  #The output should be : 1 2 3
user_input = 1 2 3 # as list int_data = 1 2 3 4 5 # as int # How to loop output only the int_data that has the same value with user_input # something like : for user_input in int_data: print int_data #The output should be : 1 2 3

well you could try this:

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
user_input = [ 1, 2, 3 ] #all are integers
int_data = [ 1, 2, 3, 4, 5 ] #all are integers
for num in user_input:
    for data in int_data:
        if num == data:
            print data
user_input = [ 1, 2, 3 ] #all are integers
int_data = [ 1, 2, 3, 4, 5 ] #all are integers
for num in user_input:
    for data in int_data:
        if num == data:
            print data

you have to be careful though if you want to use this in files,

hope it helps

Last edited by masterofpuppets; Nov 6th, 2009 at 1:03 pm.

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Join Date: Jul 2008

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jlm699

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Nov 6th, 2009

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Originally Posted by masterofpuppets

well you could try this:
Help with Code Tags

Python Syntax (Toggle Plain Text)
user_input = [ 1, 2, 3 ] #all are integers
int_data = [ 1, 2, 3, 4, 5 ] #all are integers
for num in user_input:
    for data in int_data:
        if num == data:
            print data
user_input = [ 1, 2, 3 ] #all are integers int_data = [ 1, 2, 3, 4, 5 ] #all are integers for num in user_input: for data in int_data: if num == data: print data
you have to be careful though if you want to use this in files,
hope it helps

I think that this may simply be the same thing using different logic:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
user_input = [ 1, 2, 3 ] #all are integers
int_data = [ 1, 2, 3, 4, 5 ] #all are integers
for num in user_input:
    if num in int_data:
        print num
user_input = [ 1, 2, 3 ] #all are integers
int_data = [ 1, 2, 3, 4, 5 ] #all are integers
for num in user_input:
    if num in int_data:
        print num

And further consolidation gives us this list comprehension:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
filtered_data = [data for data in user_input if data in int_data]
filtered_data = [data for data in user_input if data in int_data]

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Join Date: Jul 2009

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masterofpuppets masterofpuppets is offline

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Nov 6th, 2009

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Originally Posted by jlm699

I think that this may simply be the same thing using different logic:
Help with Code Tags

python Syntax (Toggle Plain Text)
user_input = [ 1, 2, 3 ] #all are integers
int_data = [ 1, 2, 3, 4, 5 ] #all are integers
for num in user_input:
    if num in int_data:
        print num
user_input = [ 1, 2, 3 ] #all are integers int_data = [ 1, 2, 3, 4, 5 ] #all are integers for num in user_input: if num in int_data: print num
And further consolidation gives us this list comprehension:
Help with Code Tags

python Syntax (Toggle Plain Text)
filtered_data = [data for data in user_input if data in int_data]
filtered_data = [data for data in user_input if data in int_data]

yeah bro that's much shorter

I don't know how to use this thing though:

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
filtered_data = [data for data in user_input if data in int_data]
filtered_data = [data for data in user_input if data in int_data]

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"My belief is stronger than your doubt."

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vegaseat

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DaniWeb's Hypocrite

Nov 6th, 2009

This problem really asks for the use of a dictionary object ...

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
# typical test data
data = """\
1   20
2   56
3   42
4   53
5   90
6   33
"""
 
fname = 'mytest123.txt'
# write test data to a file
fout = open(fname, "w")
fout.write(data)
fout.close()
 
# read the test file and convert to user_val:value dictionary
user_dict = {}
for line in open(fname):
    # remove trailing newline char
    line = line.rstrip()
    key, val = line.split()
    user_dict[key] = val
 
print user_dict  # test
"""result -->
{'1': '20', '3': '42', '2': '56', '5': '90', '4': '53', '6': '33'}
"""
 
# assume user input from the commandline is ...
user_input = '1,2,3'
for user_val in user_input.split(','):
    print user_val, user_dict[user_val]
 
"""result -->
1 20
2 56
3 42
"""
# typical test data
data = """\
1   20
2   56
3   42
4   53
5   90
6   33
"""

fname = 'mytest123.txt'
# write test data to a file
fout = open(fname, "w")
fout.write(data)
fout.close()

# read the test file and convert to user_val:value dictionary
user_dict = {}
for line in open(fname):
    # remove trailing newline char
    line = line.rstrip()
    key, val = line.split()
    user_dict[key] = val

print user_dict  # test
"""result -->
{'1': '20', '3': '42', '2': '56', '5': '90', '4': '53', '6': '33'}
"""

# assume user input from the commandline is ...
user_input = '1,2,3'
for user_val in user_input.split(','):
    print user_val, user_dict[user_val]

"""result -->
1 20
2 56
3 42
"""