escape sequences in list comprehensions

[kartik]

Escape sequences don't seem to work in strings within list comprehensions:

print ['%s\n' %i for i in [1,2,3]]

['1\n', '2\n', '3\n']

What am I missing?

Thank you.

 

[Kent Johnson]

Escape sequences don't seem to work in strings within list comprehensions:

print ['%s\n' %i for i in [1,2,3]]

['1\n', '2\n', '3\n']

What am I missing?

This is correct; what were you expecting?

When you print a list, it prints the repr() of the list elements. In the
case of strings, it shows you the escaped form of the string. Maybe this
is what you want:

>>> a=['%s\n' %i for i in [1,2,3]]
>>> a ['1\n', '2\n', '3\n']
>>> for x in a:

.... print x
....
1

2

3

Note the extra lines when the strings are actually printed.

Kent

 

[Russell Blau]

Escape sequences don't seem to work in strings within list comprehensions:

print ['%s\n' %i for i in [1,2,3]]

['1\n', '2\n', '3\n']

What am I missing?

You're missing what happens when you print *any* list containing strings:

print ['\n', '\n']

['\n', '\n']

 

[Bruno Desthuilliers]

Escape sequences don't seem to work in strings within list comprehensions:

print ['%s\n' %i for i in [1,2,3]]

['1\n', '2\n', '3\n']

What am I missing?

Other have answered to this question.

Just try this instead :
print "\n".join(["%d" % i for i in [1,2,3]])

Thank you.

HTH

 

[Peter Hansen]

Escape sequences don't seem to work in strings within list comprehensions:

print ['%s\n' %i for i in [1,2,3]]

['1\n', '2\n', '3\n']

What am I missing?

Others have answered, but not explained. When you print
a list (in other words, when you display the results of
calling str() on a list), the list chooses how to display
itself. It chooses to display the brackets at the start
and end, the commas separating the items, and the results
of calling repr() on each individual item. That means
that strings are shown with quotation marks (which are not
part of the string normally) and with special characters
represented as escape sequences.

The following appears to be what you believed you wanted,
though it's not really what you wanted <wink>:

lst = ['%s\n' % i for i in [1,2,3]]
print '[' + ', '.join([str(x) for x in lst]) + ']'

-Peter

 

[Bengt Richter]

Escape sequences don't seem to work in strings within list comprehensions:

print ['%s\n' %i for i in [1,2,3]]

['1\n', '2\n', '3\n']

What am I missing?

Others have answered, but not explained. When you print
a list (in other words, when you display the results of
calling str() on a list), the list chooses how to display
itself. It chooses to display the brackets at the start
and end, the commas separating the items, and the results
of calling repr() on each individual item. That means
that strings are shown with quotation marks (which are not
part of the string normally) and with special characters
represented as escape sequences.

The following appears to be what you believed you wanted,
though it's not really what you wanted <wink>:

lst = ['%s\n' % i for i in [1,2,3]]
print '[' + ', '.join([str(x) for x in lst]) + ']'

Maybe this is what he wanted (not recommended for general use ;-):
... def __repr__(self): return str(self)
...

Plain:

>>> lst = ['%s\n' % i for i in [1,2,3]]
>>> lst

['1\n', '2\n', '3\n']

Funny:

>>> lst = [FunnyStr('%s\n' % i) for i in [1,2,3]]
>>> lst

[1
, 2
, 3
] [1
, 2
, 3
]

Regards,
Bengt Richter

 

[Josiah Carlson]

Escape sequences don't seem to work in strings within list comprehensions:

print ['%s\n' %i for i in [1,2,3]]

['1\n', '2\n', '3\n']

What am I missing?

Others have answered, but not explained. When you print
a list (in other words, when you display the results of
calling str() on a list), the list chooses how to display
itself. It chooses to display the brackets at the start
and end, the commas separating the items, and the results
of calling repr() on each individual item. That means
that strings are shown with quotation marks (which are not
part of the string normally) and with special characters
represented as escape sequences.

The following appears to be what you believed you wanted,
though it's not really what you wanted <wink>:

lst = ['%s\n' % i for i in [1,2,3]]
print '[' + ', '.join([str(x) for x in lst]) + ']'

Maybe this is what he wanted (not recommended for general use ;-):
... def __repr__(self): return str(self)
...

Plain:

lst = ['%s\n' % i for i in [1,2,3]]
lst

['1\n', '2\n', '3\n']

Funny:

lst = [FunnyStr('%s\n' % i) for i in [1,2,3]]
lst

[1
, 2
, 3
][1
, 2
, 3
]

If that's really what he wants, he should take a look at the pprint
module.

- Josiah