Pythonic way to print list items
Question:
I would like to know if there is a better way to print all objects in a Python list than this :
myList = [Person("Foo"), Person("Bar")]
print("n".join(map(str, myList)))
Foo
Bar
I read this way is not really good :
myList = [Person("Foo"), Person("Bar")]
for p in myList:
print(p)
Isn’t there something like :
print(p) for p in myList
If not, my question is… why ? If we can do this kind of stuff with comprehensive lists, why not as a simple statement outside a list ?
Answers:
Assuming you are using Python 3:
print(*myList, sep='n')
This is a kind of unpacking. Details in the Python tutorial: Unpacking Argument Lists
You can get the same behavior on Python 2 using from __future__ import print_function.
With the print statement on Python 2 you will need iteration of some kind. Regarding your question about print(p) for p in myList not working, you can just use the following which does the same thing and is still simple:
for p in myList:
print p
For a solution that uses 'n'.join(), I prefer list comprehensions and generators over map() so I would probably use the following:
print 'n'.join(str(p) for p in myList)
I use this all the time:
l = [1,2,3,7]
print "".join([str(x) for x in l])
For Python 2.*:
If you overload the function __str__() for your Person class, you can omit the part with map(str, …). Another way for this is creating a function, just like you wrote:
def write_list(lst):
for item in lst:
print str(item)
...
write_list(MyList)
There is in Python 3.* the argument sep for the print() function. Take a look at documentation.
[print(a) for a in list] will give a bunch of None types at the end though it prints out all the items
Expanding @lucasg’s answer (inspired by the comment it received):
To get a formatted list output, you can do something along these lines:
l = [1,2,5]
print ", ".join('%02d'%x for x in l)
01, 02, 05
Now the ", " provides the separator (only between items, not at the end) and the formatting string '02d'combined with %x gives a formatted string for each item x – in this case, formatted as an integer with two digits, left-filled with zeros.
To display each content, I use:
mylist = ['foo', 'bar']
indexval = 0
for i in range(len(mylist)):
print(mylist[indexval])
indexval += 1
Example of using in a function:
def showAll(listname, startat):
indexval = startat
try:
for i in range(len(mylist)):
print(mylist[indexval])
indexval = indexval + 1
except IndexError:
print('That index value you gave is out of range.')
I think this is the most convenient if you just want to see the content in the list:
myList = ['foo', 'bar']
print('myList is %s' % myList)
Simple, easy to read and can be used together with format string.
Assuming you are fine with your list being printed [1,2,3], then an easy way in Python3 is:
mylist=[1,2,3,'lorem','ipsum','dolor','sit','amet']
print(f"There are {len(mylist):d} items in this lorem list: {mylist}")
Running this produces the following output:
There are 8 items in this lorem list: [1, 2, 3, ‘lorem’, ‘ipsum’,
‘dolor’, ‘sit’, ‘amet’]
OP’s question is: does something like following exists, if not then why
print(p) for p in myList # doesn't work, OP's intuition
answer is, it does exist which is:
[p for p in myList] #works perfectly
Basically, use [] for list comprehension and get rid of print to avoiding printing None. To see why print prints None see this
I recently made a password generator and although I’m VERY NEW to python, I whipped this up as a way to display all items in a list (with small edits to fit your needs…
x = 0
up = 0
passwordText = ""
password = []
userInput = int(input("Enter how many characters you want your password to be: "))
print("nnn") # spacing
while x <= (userInput - 1): #loops as many times as the user inputs above
password.extend([choice(groups.characters)]) #adds random character from groups file that has all lower/uppercase letters and all numbers
x = x+1 #adds 1 to x w/o using x ++1 as I get many errors w/ that
passwordText = passwordText + password[up]
up = up+1 # same as x increase
print(passwordText)
Like I said, IM VERY NEW to Python and I’m sure this is way to clunky for a expert, but I’m just here for another example
To print each element of a given list using a single line code
for i in result: print(i)
You can also make use of the len() function and identify the length of the list to print the elements as shown in the below example:
sample_list = ['Python', 'is', 'Easy']
for i in range(0, len(sample_list)):
print(sample_list[i])
Reference : https://favtutor.com/blogs/print-list-python
you can try doing this: this will also print it as a string
print(''.join([p for p in myList]))
or if you want to a make it print a newline every time it prints something
print(''.join([p+'n' for p in myList]))
I would like to know if there is a better way to print all objects in a Python list than this :
myList = [Person("Foo"), Person("Bar")]
print("n".join(map(str, myList)))
Foo
Bar
I read this way is not really good :
myList = [Person("Foo"), Person("Bar")]
for p in myList:
print(p)
Isn’t there something like :
print(p) for p in myList
If not, my question is… why ? If we can do this kind of stuff with comprehensive lists, why not as a simple statement outside a list ?
Assuming you are using Python 3:
print(*myList, sep='n')
This is a kind of unpacking. Details in the Python tutorial: Unpacking Argument Lists
You can get the same behavior on Python 2 using from __future__ import print_function.
With the print statement on Python 2 you will need iteration of some kind. Regarding your question about print(p) for p in myList not working, you can just use the following which does the same thing and is still simple:
for p in myList:
print p
For a solution that uses 'n'.join(), I prefer list comprehensions and generators over map() so I would probably use the following:
print 'n'.join(str(p) for p in myList)
I use this all the time:
l = [1,2,3,7]
print "".join([str(x) for x in l])
For Python 2.*:
If you overload the function __str__() for your Person class, you can omit the part with map(str, …). Another way for this is creating a function, just like you wrote:
def write_list(lst):
for item in lst:
print str(item)
...
write_list(MyList)
There is in Python 3.* the argument sep for the print() function. Take a look at documentation.
[print(a) for a in list] will give a bunch of None types at the end though it prints out all the items
Expanding @lucasg’s answer (inspired by the comment it received):
To get a formatted list output, you can do something along these lines:
l = [1,2,5]
print ", ".join('%02d'%x for x in l)
01, 02, 05
Now the ", " provides the separator (only between items, not at the end) and the formatting string '02d'combined with %x gives a formatted string for each item x – in this case, formatted as an integer with two digits, left-filled with zeros.
To display each content, I use:
mylist = ['foo', 'bar']
indexval = 0
for i in range(len(mylist)):
print(mylist[indexval])
indexval += 1
Example of using in a function:
def showAll(listname, startat):
indexval = startat
try:
for i in range(len(mylist)):
print(mylist[indexval])
indexval = indexval + 1
except IndexError:
print('That index value you gave is out of range.')
I think this is the most convenient if you just want to see the content in the list:
myList = ['foo', 'bar']
print('myList is %s' % myList)
Simple, easy to read and can be used together with format string.
Assuming you are fine with your list being printed [1,2,3], then an easy way in Python3 is:
mylist=[1,2,3,'lorem','ipsum','dolor','sit','amet']
print(f"There are {len(mylist):d} items in this lorem list: {mylist}")
Running this produces the following output:
There are 8 items in this lorem list: [1, 2, 3, ‘lorem’, ‘ipsum’,
‘dolor’, ‘sit’, ‘amet’]
OP’s question is: does something like following exists, if not then why
print(p) for p in myList # doesn't work, OP's intuition
answer is, it does exist which is:
[p for p in myList] #works perfectly
Basically, use [] for list comprehension and get rid of print to avoiding printing None. To see why print prints None see this
I recently made a password generator and although I’m VERY NEW to python, I whipped this up as a way to display all items in a list (with small edits to fit your needs…
x = 0
up = 0
passwordText = ""
password = []
userInput = int(input("Enter how many characters you want your password to be: "))
print("nnn") # spacing
while x <= (userInput - 1): #loops as many times as the user inputs above
password.extend([choice(groups.characters)]) #adds random character from groups file that has all lower/uppercase letters and all numbers
x = x+1 #adds 1 to x w/o using x ++1 as I get many errors w/ that
passwordText = passwordText + password[up]
up = up+1 # same as x increase
print(passwordText)
Like I said, IM VERY NEW to Python and I’m sure this is way to clunky for a expert, but I’m just here for another example
To print each element of a given list using a single line code
for i in result: print(i)
You can also make use of the len() function and identify the length of the list to print the elements as shown in the below example:
sample_list = ['Python', 'is', 'Easy']
for i in range(0, len(sample_list)):
print(sample_list[i])
Reference : https://favtutor.com/blogs/print-list-python
you can try doing this: this will also print it as a string
print(''.join([p for p in myList]))
or if you want to a make it print a newline every time it prints something
print(''.join([p+'n' for p in myList]))