Format string in python

Question

I have to write one string as follows:

A = 55
B = 45

res = 'A =' + str(A) + '\n' + \
            'B = ' + str(B)

The A and B have to be separated into two lines.

print res

Result is correct. However, if i have other variables such as C,D,E, etc. doing one by one as in my code is difficult. What is shorter and easier way for doing it?

Do you mean that your variables will always be single character alphabet from A to Z max ? — Afroz Alam
– Afroz Alam, Commented Sep 9, 2015 at 11:38
Where are the variables defined? Are they within a function? Not that I recommend it, but could you hack something together with locals()? — mhawke
– mhawke, Commented Sep 9, 2015 at 11:48

ralh · Accepted Answer · 2015-09-09 11:55:38Z

2

You could make a dictionary of the values and iterate over it:

values = {
    'A': 56,
    'B': 32,
    'C': 34
}

res = ''
for key in values:
    res += key + ' = ' + str(values[key]) + '\n'

If you want to have the values in order, you should use an OrderedDict, as suggested in the answer by Peter Woods.

edited Sep 9, 2015 at 11:55

answered Sep 9, 2015 at 11:43

ralh

2,5941 gold badge16 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

gudlife Over a year ago

its more manual than mine. The given values are separated by variable names and not in the dictionary form

ralh Over a year ago

Well, I don't think it's possible to automate it in any way without grouping the variables somehow. You need to specify how to access the list of variables.

Open AI - Opting Out Over a year ago

What order do the values come out?

ralh Over a year ago

It is true you should use an OrderedDict. Not sure if I should edit my answer to reflect that, cos I would feel like stealing from you, but perhaps I should for it to be correct.

Open AI - Opting Out Over a year ago

@ralh Go ahead and edit your answer if you like. Not stealing, just make your answer the best you think you can. No shame in that (c:

SuperBiasedMan · Accepted Answer · 2015-09-09 11:48:05Z

1

You can use str.format to determine res easier:

res = 'A ={}\nB = {}'.format(A, B)

The {} are replaced with the parameters that you pass to format and you can pass in as many as you want.

answered Sep 9, 2015 at 11:48

SuperBiasedMan

10k11 gold badges52 silver badges76 bronze badges

3 Comments

mhawke Over a year ago

This is shorter but it doesn't really answer the question. You still need to hand code the variable names into the format string.

SuperBiasedMan Over a year ago

@mhawke But you no longer need to add + str(var) + for each one, which I believe is the OP's concern.

mhawke Over a year ago

Yeah, I'm not really sure what the main concern is... I think that OP is after something that will automate the insertion of the variable names into the output string too.

pacholik · Accepted Answer · 2015-09-09 12:00:37Z

1

If you want to process all your variables (e.g. you are in function) you can use locals

def f():
    A = 55
    B = 45
    C = 35
    D = 25
    print("\n".join("{} = {}".format(k, v) for k,v in locals().items()))

in action:

>>> f()
A = 55
B = 45
C = 35
D = 25

Otherwise we have to know which variables do you want to process - for example, use OrderedDict:

d = OrderedDict([
("A", 55),
("B", 45),
("C", 35),
("D", 25),
])

print("\n".join("{} = {}".format(k, v) for k,v in d.items()))

answered Sep 9, 2015 at 12:00

pacholik

9,0529 gold badges48 silver badges59 bronze badges

1 Comment

pacholik Over a year ago

If you use kwargs, your ordering is lost.

Sdwdaw · Accepted Answer · 2015-09-09 11:49:09Z

0

First of all don't start variable names from uppercase. If you want to print all values you should have more usefull data structure. Like list or dictionary.

>>> dictionary = {'a':55, 'b':45, 'c':65}
>>> for key, value in dictionary.items():
...     print str(key) + ' = ' + str(value)
... 
a = 55
c = 65
b = 45

If you want to have sorted output, create a list of strings first:

>>> list = []
>>> for key, value in dictionary.iteritems():
...     list.append(str(key) + ' = ' + str(value))
... 
>>> list
['a = 55', 'c = 65', 'b = 45']
>>> for el in sorted(list):
...     print el
... 
a = 55
b = 45
c = 65

answered Sep 9, 2015 at 11:49

Sdwdaw

1,0377 silver badges14 bronze badges

Comments

nekomatic · Accepted Answer · 2015-09-09 12:40:38Z

-1

A = 45
B = 55
C = 65

names = ['A', 'B', 'C'] # list of variable names
res = '\n'.join([varname + ' =' + str(locals()[varname]) for varname in names])

This does what you've asked for, but if it's going to be used in a practical program I would look at other methods for storing and retrieving the data such as a dictionary.

edited Sep 9, 2015 at 12:40

answered Sep 9, 2015 at 11:49

nekomatic

6,2841 gold badge23 silver badges27 bronze badges

4 Comments

SuperBiasedMan Over a year ago

eval can cause some serious issues if not used carefully.

gudlife Over a year ago

@SuperBiasedMan i am using this code zipping the names and values without using eval

pacholik Over a year ago

Don't use eval when you have propper substitute - globals()[varname] (or, sufficient enough in this example, locals).

nekomatic Over a year ago

Thanks all for the comments, I've edited my answer to use locals().

Collectives™ on Stack Overflow

Format string in python

5 Answers 5

5 Comments

3 Comments

1 Comment

Comments

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

5 Comments

3 Comments

1 Comment

Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related