How the sum() function works in python?
sum({'x':-10,'y':-20,'z':-30},60)
#TypeError: unsupported operand type(s) for +: 'int' and 'str'
but
sum({-10: 'x', -20: 'y', -30: 'z'},60)
#returns 0
python-3.x
edited Nov 17 '18 at 13:14
jonrsharpe
77.2k11103208
asked Nov 17 '18 at 13:13
Damodara SahuDamodara Sahu
216
add a comment |
sum({'x':-10,'y':-20,'z':-30},60)
#TypeError: unsupported operand type(s) for +: 'int' and 'str'
but
sum({-10: 'x', -20: 'y', -30: 'z'},60)
#returns 0
python-3.x
edited Nov 17 '18 at 13:14
jonrsharpe
77.2k11103208
asked Nov 17 '18 at 13:13
Damodara SahuDamodara Sahu
216
2
When you iterate over a dictionary you iterate over its keys. This is demonstrated by the examples you've posted.
– jonrsharpe
Nov 17 '18 at 13:14
sum([4],[1,2,3]) #why this error message appears:TypeError: can only concatenate list (not "int") to list
– Damodara Sahu
Nov 17 '18 at 13:50
Because it's trying to do[1, 2, 3] + 4, that doesn't make sense.
– jonrsharpe
Nov 17 '18 at 14:02
Can we able to add the contents of two lists using sum method; just like, [1,2,3] add [4] results to 10?
– Damodara Sahu
Nov 18 '18 at 12:55
Not just using sum once, no; you'd need to combine the lists then sum them, e.g.:sum([1, 2, 3] + [4]).
– jonrsharpe
Nov 18 '18 at 12:56
add a comment |
sum({'x':-10,'y':-20,'z':-30},60)
#TypeError: unsupported operand type(s) for +: 'int' and 'str'
but
sum({-10: 'x', -20: 'y', -30: 'z'},60)
#returns 0
python-3.x
edited Nov 17 '18 at 13:14
jonrsharpe
77.2k11103208
asked Nov 17 '18 at 13:13
Damodara SahuDamodara Sahu
216
sum({'x':-10,'y':-20,'z':-30},60)
#TypeError: unsupported operand type(s) for +: 'int' and 'str'
but
sum({-10: 'x', -20: 'y', -30: 'z'},60)
#returns 0
python-3.x
python-3.x
edited Nov 17 '18 at 13:14
jonrsharpe
77.2k11103208
asked Nov 17 '18 at 13:13
Damodara SahuDamodara Sahu
216
edited Nov 17 '18 at 13:14
jonrsharpe
77.2k11103208
asked Nov 17 '18 at 13:13
Damodara SahuDamodara Sahu
216
edited Nov 17 '18 at 13:14
jonrsharpe
77.2k11103208
edited Nov 17 '18 at 13:14
jonrsharpe
77.2k11103208
edited Nov 17 '18 at 13:14
jonrsharpe
77.2k11103208
77.2k11103208
asked Nov 17 '18 at 13:13
Damodara SahuDamodara Sahu
216
asked Nov 17 '18 at 13:13
Damodara SahuDamodara Sahu
216
asked Nov 17 '18 at 13:13
Damodara SahuDamodara Sahu
216
216
2
When you iterate over a dictionary you iterate over its keys. This is demonstrated by the examples you've posted.
– jonrsharpe
Nov 17 '18 at 13:14
sum([4],[1,2,3]) #why this error message appears:TypeError: can only concatenate list (not "int") to list
– Damodara Sahu
Nov 17 '18 at 13:50
Because it's trying to do[1, 2, 3] + 4, that doesn't make sense.
– jonrsharpe
Nov 17 '18 at 14:02
Can we able to add the contents of two lists using sum method; just like, [1,2,3] add [4] results to 10?
– Damodara Sahu
Nov 18 '18 at 12:55
Not just using sum once, no; you'd need to combine the lists then sum them, e.g.:sum([1, 2, 3] + [4]).
– jonrsharpe
Nov 18 '18 at 12:56
add a comment |
2
When you iterate over a dictionary you iterate over its keys. This is demonstrated by the examples you've posted.
– jonrsharpe
Nov 17 '18 at 13:14
sum([4],[1,2,3]) #why this error message appears:TypeError: can only concatenate list (not "int") to list
– Damodara Sahu
Nov 17 '18 at 13:50
Because it's trying to do[1, 2, 3] + 4, that doesn't make sense.
– jonrsharpe
Nov 17 '18 at 14:02
Can we able to add the contents of two lists using sum method; just like, [1,2,3] add [4] results to 10?
– Damodara Sahu
Nov 18 '18 at 12:55
Not just using sum once, no; you'd need to combine the lists then sum them, e.g.:sum([1, 2, 3] + [4]).
– jonrsharpe
Nov 18 '18 at 12:56
2
2
When you iterate over a dictionary you iterate over its keys. This is demonstrated by the examples you've posted.
– jonrsharpe
Nov 17 '18 at 13:14
When you iterate over a dictionary you iterate over its keys. This is demonstrated by the examples you've posted.
– jonrsharpe
Nov 17 '18 at 13:14
sum([4],[1,2,3]) #why this error message appears:TypeError: can only concatenate list (not "int") to list
– Damodara Sahu
Nov 17 '18 at 13:50
sum([4],[1,2,3]) #why this error message appears:TypeError: can only concatenate list (not "int") to list
– Damodara Sahu
Nov 17 '18 at 13:50
Because it's trying to do
[1, 2, 3] + 4, that doesn't make sense.– jonrsharpe
Nov 17 '18 at 14:02
Because it's trying to do
[1, 2, 3] + 4, that doesn't make sense.– jonrsharpe
Nov 17 '18 at 14:02
Can we able to add the contents of two lists using sum method; just like, [1,2,3] add [4] results to 10?
– Damodara Sahu
Nov 18 '18 at 12:55
Can we able to add the contents of two lists using sum method; just like, [1,2,3] add [4] results to 10?
– Damodara Sahu
Nov 18 '18 at 12:55
Not just using sum once, no; you'd need to combine the lists then sum them, e.g.:
sum([1, 2, 3] + [4]).– jonrsharpe
Nov 18 '18 at 12:56
Not just using sum once, no; you'd need to combine the lists then sum them, e.g.:
sum([1, 2, 3] + [4]).– jonrsharpe
Nov 18 '18 at 12:56
add a comment |
2 Answers
2
active
oldest
votes
As explained on Python's documentation, the sum function will sum the start value (2nd argument) with the items from an iterable data structure (1st argument). And, as mentioned on the comments, a dict by default is iterable over its keys.
Thus, your second example is adding 60 (your start value) with your numerical dict items (keys):
>>> 60 + (-10) + (-20) + (-30)
0
Your first example, however, is trying to add strings to numbers, which is not what sum() was intended to do:
>>> 60 + 'x' + 'y' + 'z'
(...) TypeError: unsupported operand type(s) for +: 'int' and 'str'
If you want, for instance, to iterate a dict over its values you can use the values() function. For example:
sum({'x':-10,'y':-20,'z':-30}.values(),60)
answered Nov 17 '18 at 14:17
Aurora WangAurora Wang
713216
Thanq. So nice explanation.
– Damodara Sahu
Nov 17 '18 at 22:06
add a comment |
Basically, sum({'x':-10,'y':-20,'z':-30},60) will result in an error as the program will encounter strings instead of integers as keys. Obviously, the program won't add 60 to strings as that operation doesn't make any sense. What is the result of 'x' + 'y', 'z' + 60?
In the second example,sum({-10: 'x', -20: 'y', -30: 'z'},60) the program iterates over integers only. That's why you have received 0 as the sum of -10, -20, -30 + 60 = 0. That makes sense.
Hope this helps.
answered Nov 17 '18 at 14:33
Abdulaziz Al JumaiaAbdulaziz Al Jumaia
118113
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
As explained on Python's documentation, the sum function will sum the start value (2nd argument) with the items from an iterable data structure (1st argument). And, as mentioned on the comments, a dict by default is iterable over its keys.
Thus, your second example is adding 60 (your start value) with your numerical dict items (keys):
>>> 60 + (-10) + (-20) + (-30)
0
Your first example, however, is trying to add strings to numbers, which is not what sum() was intended to do:
>>> 60 + 'x' + 'y' + 'z'
(...) TypeError: unsupported operand type(s) for +: 'int' and 'str'
If you want, for instance, to iterate a dict over its values you can use the values() function. For example:
sum({'x':-10,'y':-20,'z':-30}.values(),60)
answered Nov 17 '18 at 14:17
Aurora WangAurora Wang
713216
Thanq. So nice explanation.
– Damodara Sahu
Nov 17 '18 at 22:06
add a comment |
As explained on Python's documentation, the sum function will sum the start value (2nd argument) with the items from an iterable data structure (1st argument). And, as mentioned on the comments, a dict by default is iterable over its keys.
Thus, your second example is adding 60 (your start value) with your numerical dict items (keys):
>>> 60 + (-10) + (-20) + (-30)
0
Your first example, however, is trying to add strings to numbers, which is not what sum() was intended to do:
>>> 60 + 'x' + 'y' + 'z'
(...) TypeError: unsupported operand type(s) for +: 'int' and 'str'
If you want, for instance, to iterate a dict over its values you can use the values() function. For example:
sum({'x':-10,'y':-20,'z':-30}.values(),60)
answered Nov 17 '18 at 14:17
Aurora WangAurora Wang
713216
Thanq. So nice explanation.
– Damodara Sahu
Nov 17 '18 at 22:06
add a comment |
As explained on Python's documentation, the sum function will sum the start value (2nd argument) with the items from an iterable data structure (1st argument). And, as mentioned on the comments, a dict by default is iterable over its keys.
Thus, your second example is adding 60 (your start value) with your numerical dict items (keys):
>>> 60 + (-10) + (-20) + (-30)
0
Your first example, however, is trying to add strings to numbers, which is not what sum() was intended to do:
>>> 60 + 'x' + 'y' + 'z'
(...) TypeError: unsupported operand type(s) for +: 'int' and 'str'
If you want, for instance, to iterate a dict over its values you can use the values() function. For example:
sum({'x':-10,'y':-20,'z':-30}.values(),60)
answered Nov 17 '18 at 14:17
Aurora WangAurora Wang
713216
As explained on Python's documentation, the sum function will sum the start value (2nd argument) with the items from an iterable data structure (1st argument). And, as mentioned on the comments, a dict by default is iterable over its keys.
Thus, your second example is adding 60 (your start value) with your numerical dict items (keys):
>>> 60 + (-10) + (-20) + (-30)
0
Your first example, however, is trying to add strings to numbers, which is not what sum() was intended to do:
>>> 60 + 'x' + 'y' + 'z'
(...) TypeError: unsupported operand type(s) for +: 'int' and 'str'
If you want, for instance, to iterate a dict over its values you can use the values() function. For example:
sum({'x':-10,'y':-20,'z':-30}.values(),60)
answered Nov 17 '18 at 14:17
Aurora WangAurora Wang
713216
answered Nov 17 '18 at 14:17
Aurora WangAurora Wang
713216
answered Nov 17 '18 at 14:17
Aurora WangAurora Wang
713216
answered Nov 17 '18 at 14:17
Aurora WangAurora Wang
713216
713216
Thanq. So nice explanation.
– Damodara Sahu
Nov 17 '18 at 22:06
add a comment |
Thanq. So nice explanation.
– Damodara Sahu
Nov 17 '18 at 22:06
Thanq. So nice explanation.
– Damodara Sahu
Nov 17 '18 at 22:06
Thanq. So nice explanation.
– Damodara Sahu
Nov 17 '18 at 22:06
add a comment |
Basically, sum({'x':-10,'y':-20,'z':-30},60) will result in an error as the program will encounter strings instead of integers as keys. Obviously, the program won't add 60 to strings as that operation doesn't make any sense. What is the result of 'x' + 'y', 'z' + 60?
In the second example,sum({-10: 'x', -20: 'y', -30: 'z'},60) the program iterates over integers only. That's why you have received 0 as the sum of -10, -20, -30 + 60 = 0. That makes sense.
Hope this helps.
answered Nov 17 '18 at 14:33
Abdulaziz Al JumaiaAbdulaziz Al Jumaia
118113
add a comment |
Basically, sum({'x':-10,'y':-20,'z':-30},60) will result in an error as the program will encounter strings instead of integers as keys. Obviously, the program won't add 60 to strings as that operation doesn't make any sense. What is the result of 'x' + 'y', 'z' + 60?
In the second example,sum({-10: 'x', -20: 'y', -30: 'z'},60) the program iterates over integers only. That's why you have received 0 as the sum of -10, -20, -30 + 60 = 0. That makes sense.
Hope this helps.
answered Nov 17 '18 at 14:33
Abdulaziz Al JumaiaAbdulaziz Al Jumaia
118113
add a comment |
Basically, sum({'x':-10,'y':-20,'z':-30},60) will result in an error as the program will encounter strings instead of integers as keys. Obviously, the program won't add 60 to strings as that operation doesn't make any sense. What is the result of 'x' + 'y', 'z' + 60?
In the second example,sum({-10: 'x', -20: 'y', -30: 'z'},60) the program iterates over integers only. That's why you have received 0 as the sum of -10, -20, -30 + 60 = 0. That makes sense.
Hope this helps.
answered Nov 17 '18 at 14:33
Abdulaziz Al JumaiaAbdulaziz Al Jumaia
118113
Basically, sum({'x':-10,'y':-20,'z':-30},60) will result in an error as the program will encounter strings instead of integers as keys. Obviously, the program won't add 60 to strings as that operation doesn't make any sense. What is the result of 'x' + 'y', 'z' + 60?
In the second example,sum({-10: 'x', -20: 'y', -30: 'z'},60) the program iterates over integers only. That's why you have received 0 as the sum of -10, -20, -30 + 60 = 0. That makes sense.
Hope this helps.
answered Nov 17 '18 at 14:33
Abdulaziz Al JumaiaAbdulaziz Al Jumaia
118113
answered Nov 17 '18 at 14:33
Abdulaziz Al JumaiaAbdulaziz Al Jumaia
118113
answered Nov 17 '18 at 14:33
Abdulaziz Al JumaiaAbdulaziz Al Jumaia
118113
answered Nov 17 '18 at 14:33
Abdulaziz Al JumaiaAbdulaziz Al Jumaia
118113
118113
add a comment |
add a comment |
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2
When you iterate over a dictionary you iterate over its keys. This is demonstrated by the examples you've posted.
– jonrsharpe
Nov 17 '18 at 13:14
sum([4],[1,2,3]) #why this error message appears:TypeError: can only concatenate list (not "int") to list
– Damodara Sahu
Nov 17 '18 at 13:50
Because it's trying to do
[1, 2, 3] + 4, that doesn't make sense.– jonrsharpe
Nov 17 '18 at 14:02
Can we able to add the contents of two lists using sum method; just like, [1,2,3] add [4] results to 10?
– Damodara Sahu
Nov 18 '18 at 12:55
Not just using sum once, no; you'd need to combine the lists then sum them, e.g.:
sum([1, 2, 3] + [4]).– jonrsharpe
Nov 18 '18 at 12:56