Inserting '-' character in front of all numbers in a string

**kyosohma@gmail.com** · Mar 30 '07, 03:55 PM

Re: Inserting '-' character in front of all numbers in a string

On Mar 30, 10:38 am, "kevinliu23 " <kevinli...@gma il.comwrote:

Hey guys,
>
I want to be able to insert a '-' character in front of all numeric
values in a string. I want to insert the '-' character to use in
conjunction with the getopt.getopt() function.
>
Rigt now, I'm implementing a menu system where users will be able to
select a set of options like "2a 3ab" which corresponds to menu
choices. However, with getopt.getopt() , it'll only return what I want
if I input -2a -3ab as my string. I don't want the user have to insert
a '-' character in front of all their choices, so I was thinking of
accepting the string input first, then adding in the '-' character
myself.
>
So my qusetion is, how do I change:
>
"2a 3ab" into "-2a -3ab".
>
Regular expressions? :/

Regular expressions would definitely work. Here's a hack though:

tempInput = '2a 3ab'
tempLst = tempInput.split (' ')

output = ''
for i in tempLst:
output += ('-' + i + ' ')

I'm sure there are many better and more elegant hacks than this.

Mike

**Larry Bates** · Mar 30 '07, 04:05 PM

Re: Inserting '-' character in front of all numbers in a string

kevinliu23 wrote:

Hey guys,
>
I want to be able to insert a '-' character in front of all numeric
values in a string. I want to insert the '-' character to use in
conjunction with the getopt.getopt() function.
>
Rigt now, I'm implementing a menu system where users will be able to
select a set of options like "2a 3ab" which corresponds to menu
choices. However, with getopt.getopt() , it'll only return what I want
if I input -2a -3ab as my string. I don't want the user have to insert
a '-' character in front of all their choices, so I was thinking of
accepting the string input first, then adding in the '-' character
myself.
>
So my qusetion is, how do I change:
>
"2a 3ab" into "-2a -3ab".
>
Regular expressions? :/
>

s="2a 3b"
s="-%s -%s"% tuple(s.split() )

-Larry

**Marc 'BlackJack' Rintsch** · Mar 30 '07, 04:45 PM

Re: Inserting '-' character in front of all numbers in a string

In <1175269107.769 945.241500@r56g 2000hsd.googleg roups.com>, kevinliu23
wrote:

"2a 3ab" into "-2a -3ab".

In [8]: '-' + ' -'.join('2a 3ab 4xy'.split())
Out[8]: '-2a -3ab -4xy'

Ciao,
Marc 'BlackJack' Rintsch

**kevinliu23** · Mar 30 '07, 05:05 PM

Re: Inserting '-' character in front of all numbers in a string

Hey guys, thanks for the quick replies. I'm looking for something more
generic than adding it to "2a 3ab". For example, under the menu option
2, there can be upwards of 8 other suboptions. I'll see what's
suggested here and post back if I run into more problems. Thanks guys!

**Michael Bentley** · Mar 30 '07, 07:15 PM

Re: Inserting '-' character in front of all numbers in a string

On Mar 30, 2007, at 10:38 AM, kevinliu23 wrote:

I want to be able to insert a '-' character in front of all numeric
values in a string. I want to insert the '-' character to use in
conjunction with the getopt.getopt() function.
>
Rigt now, I'm implementing a menu system where users will be able to
select a set of options like "2a 3ab" which corresponds to menu
choices. However, with getopt.getopt() , it'll only return what I want
if I input -2a -3ab as my string. I don't want the user have to insert
a '-' character in front of all their choices, so I was thinking of
accepting the string input first, then adding in the '-' character
myself.
>
So my qusetion is, how do I change:
>
"2a 3ab" into "-2a -3ab".
>

Will the first character always be a digit?

for i in yourstring.spli t():
if i[0].isdigit():
yourstring = yourstring.repl ace(i, '-%s' % (i,))

Or are these hex numbers?

**Paul McGuire** · Mar 30 '07, 09:45 PM

Re: Inserting '-' character in front of all numbers in a string

On Mar 30, 2:09 pm, Michael Bentley <mich...@jedimi ndworks.comwrot e:

On Mar 30, 2007, at 10:38 AM, kevinliu23 wrote:
>
>
>
>
>

I want to be able to insert a '-' character in front of all numeric
values in a string. I want to insert the '-' character to use in
conjunction with the getopt.getopt() function.

>

Rigt now, I'm implementing a menu system where users will be able to
select a set of options like "2a 3ab" which corresponds to menu
choices. However, with getopt.getopt() , it'll only return what I want
if I input -2a -3ab as my string. I don't want the user have to insert
a '-' character in front of all their choices, so I was thinking of
accepting the string input first, then adding in the '-' character
myself.

>

So my qusetion is, how do I change:

>

"2a 3ab" into "-2a -3ab".

>
Will the first character always be a digit?
>
for i in yourstring.spli t():
if i[0].isdigit():
yourstring = yourstring.repl ace(i, '-%s' % (i,))
>
Or are these hex numbers?- Hide quoted text -
>
- Show quoted text -

Your replace strategy is risky. If:

yourstring = "1ab 2bc 3de 11ab"

it will convert to

-1ab -2bc -3de 1-1ab

-- Paul

**John Nagle** · Mar 30 '07, 10:05 PM

Re: Inserting '-' character in front of all numbers in a string

Paul McGuire wrote:

On Mar 30, 2:09 pm, Michael Bentley <mich...@jedimi ndworks.comwrot e:
>

>>On Mar 30, 2007, at 10:38 AM, kevinliu23 wrote:
>>
>>
>>
>>
>>
>>

>>>I want to be able to insert a '-' character in front of all numeric
>>>values in a string. I want to insert the '-' character to use in
>>>conjunctio n with the getopt.getopt() function.

' '.join(map(lamb da x: '-' + x, s.split()))

assuming that you just want to put a "-" in front of each field,
regardless of its content.

John Nagle

**Michael Bentley** · Mar 30 '07, 10:45 PM

Re: Inserting '-' character in front of all numbers in a string

On Mar 30, 2007, at 4:41 PM, Paul McGuire wrote:

On Mar 30, 2:09 pm, Michael Bentley <mich...@jedimi ndworks.comwrot e:

>On Mar 30, 2007, at 10:38 AM, kevinliu23 wrote:
>>
>>
>>
>>
>>

>>I want to be able to insert a '-' character in front of all numeric
>>values in a string. I want to insert the '-' character to use in
>>conjunction with the getopt.getopt() function.

>>

>>Rigt now, I'm implementing a menu system where users will be able to
>>select a set of options like "2a 3ab" which corresponds to menu
>>choices. However, with getopt.getopt() , it'll only return what I
>>want
>>if I input -2a -3ab as my string. I don't want the user have to
>>insert
>>a '-' character in front of all their choices, so I was thinking of
>>accepting the string input first, then adding in the '-' character
>>myself.

>>

>>So my qusetion is, how do I change:

>>

>>"2a 3ab" into "-2a -3ab".

>>
>Will the first character always be a digit?
>>
>for i in yourstring.spli t():
> if i[0].isdigit():
> yourstring = yourstring.repl ace(i, '-%s' % (i,))
>>
>Or are these hex numbers?- Hide quoted text -
>>
>- Show quoted text -

>
Your replace strategy is risky. If:
>
yourstring = "1ab 2bc 3de 11ab"
>
it will convert to
>
-1ab -2bc -3de 1-1ab

True enough! Good catch! How's this?

for i in yourstring.spli t():
if i[0].isdigit():
yourstring = yourstring.repl ace(i, '-%s' % (i,), 1)

**Michael Bentley** · Mar 30 '07, 11:25 PM

Re: Inserting '-' character in front of all numbers in a string

On Mar 30, 2007, at 5:42 PM, Michael Bentley wrote:

for i in yourstring.spli t():
if i[0].isdigit():
yourstring = yourstring.repl ace(i, '-%s' % (i,), 1)

*OR*

yourstring ' '.join(x[0].isdigit() and '-%s' % x or x for x in
yourstring.spli t())

;-)

**Jorgen Grahn** · Apr 3 '07, 01:25 PM

Re: Inserting '-' character in front of all numbers in a string

On 30 Mar 2007 08:38:27 -0700, kevinliu23 <kevinliu23@gma il.comwrote:

Hey guys,
>
I want to be able to insert a '-' character in front of all numeric
values in a string. I want to insert the '-' character to use in
conjunction with the getopt.getopt() function.

....

"2a 3ab" into "-2a -3ab".

Are you sure you want getopt, or are you just reusing it because you
don't know enough about string parsing and REs?

-2a -3ab is a bit limited: if you run out of digits and have to use
10, 11, ... then getopt will treat '-10ab' as '-1' without argument
and -0 with 'ab' as argument. It will probably choke on the
argumentless -1, too.

/Jorgen

--
// Jorgen Grahn <grahn@ Ph'nglui mglw'nafh Cthulhu
\X/ snipabacken.dyn dns.org R'lyeh wgah'nagl fhtagn!

Inserting '-' character in front of all numbers in a string

Inserting '-' character in front of all numbers in a string

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