list.append not working?

[Hardy]

I experience a problem with append(). This is a part of my code:

for entity in temp:
md['module']= entity.addr.get('module')
md['id']=entity.addr.get('id')
md['type']=entity.addr.get('type')
#print md
mbusentities.append(md)
#print mbusentities

I want something like: [{'module': 'home', 'id': 123, 'type': 'core'},
{'module': 'work', 'id': 456, 'type': 'core'}]
md is always correct, BUT:mbusentities is wrong. Length of
mbusentities is same of temp, so it appended everything. BUT:
mbusentities only shows the values of the last append: [{'module':
'work', 'id': 456, 'type': 'core'}, {'module': 'work', 'id': 456,
'type': 'core'}]

What's wrong?

 

[infidel]

I experience a problem with append(). This is a part of my code:

for entity in temp:
md['module']= entity.addr.get('module')
md['id']=entity.addr.get('id')
md['type']=entity.addr.get('type')
#print md
mbusentities.append(md)
#print mbusentities

I want something like: [{'module': 'home', 'id': 123, 'type': 'core'},
{'module': 'work', 'id': 456, 'type': 'core'}]
md is always correct, BUT:mbusentities is wrong. Length of
mbusentities is same of temp, so it appended everything. BUT:
mbusentities only shows the values of the last append: [{'module':
'work', 'id': 456, 'type': 'core'}, {'module': 'work', 'id': 456,
'type': 'core'}]

What's wrong?

You're reusing the same "md" dictionary over and over, appending the
same object to the list each time. So what you have is a list of
references to the same dictionary. You need to set md = {} first
thing each iteration.

 

[7stud]

I experience a problem with append(). This is a part of my code:

for entity in temp:
md['module']= entity.addr.get('module')
md['id']=entity.addr.get('id')
md['type']=entity.addr.get('type')
#print md
mbusentities.append(md)
#print mbusentities

I want something like: [{'module': 'home', 'id': 123, 'type': 'core'},
{'module': 'work', 'id': 456, 'type': 'core'}]
md is always correct, BUT:mbusentities is wrong. Length of
mbusentities is same of temp, so it appended everything. BUT:
mbusentities only shows the values of the last append: [{'module':
'work', 'id': 456, 'type': 'core'}, {'module': 'work', 'id': 456,
'type': 'core'}]

What's wrong?

Inside your loop, you assign md["module"], md["id"], and md["type"]
the same values over and over again.

 

[Hardy]

I experience a problem with append(). This is a part of my code:

for entity in temp:
md['module']= entity.addr.get('module')
md['id']=entity.addr.get('id')
md['type']=entity.addr.get('type')
#print md
mbusentities.append(md)
#print mbusentities

I want something like: [{'module': 'home', 'id': 123, 'type': 'core'},
{'module': 'work', 'id': 456, 'type': 'core'}]
md is always correct, BUT:mbusentities is wrong. Length of
mbusentities is same of temp, so it appended everything. BUT:
mbusentities only shows the values of the last append: [{'module':
'work', 'id': 456, 'type': 'core'}, {'module': 'work', 'id': 456,
'type': 'core'}]

What's wrong?

You're reusing the same "md" dictionary over and over, appending the
same object to the list each time. So what you have is a list of
references to the same dictionary. You need to set md = {} first
thing each iteration.

Thanks, that was my mistake, should take a break, getting code-blind

 

[Wildemar Wildenburger]

I experience a problem with append(). This is a part of my code:

for entity in temp:
md['module']= entity.addr.get('module')
md['id']=entity.addr.get('id')
md['type']=entity.addr.get('type')
#print md
mbusentities.append(md)
#print mbusentities

I want something like: [{'module': 'home', 'id': 123, 'type': 'core'},
{'module': 'work', 'id': 456, 'type': 'core'}]
md is always correct, BUT:mbusentities is wrong. Length of
mbusentities is same of temp, so it appended everything. BUT:
mbusentities only shows the values of the last append: [{'module':
'work', 'id': 456, 'type': 'core'}, {'module': 'work', 'id': 456,
'type': 'core'}]

What's wrong?

Inside your loop, you assign md["module"], md["id"], and md["type"]
the same values over and over again.

I may seem like a prick, but that is not the correct answer (infidel and
Abhishek gave the correct explanation). I just thought I'd point this
out to avoid confusion.

/W

 

[Wildemar Wildenburger]

with every iteration your previous values are overwritten ('md' is a
dictionary) so thats why your are observing this ouput..

check if the following patch solves your problem

for entity in temp:
md['module']= entity.addr.get('module')
md['id']=entity.addr.get('id')
md['type']=entity.addr.get('type')
#print md
mbusentities.append(md)
md = {}
#print mbusentities


Regards
Abhi

This will work, but may I suggest putting the md = {} line at the
*beginning* of the loop?
I find seeing it at the end HIGHLY confusing. Declaring it in the
beginning makes sense, because you declare/initialize, then use it. But
using and *then* initializing it for the next iteration is kind of
quirky, because it breaks the logical encapsulation I would like to see
in *one* loop iteration.

/W

 

[Rex Turnbull]

with every iteration your previous values are overwritten ('md' is a
dictionary) so thats why your are observing this ouput..

check if the following patch solves your problem

for entity in temp:
md['module']= entity.addr.get('module')
md['id']=entity.addr.get('id')
md['type']=entity.addr.get('type')
#print md
mbusentities.append(md)
md = {}
#print mbusentities


Regards
Abhi

This will work, but may I suggest putting the md = {} line at the
*beginning* of the loop?
I find seeing it at the end HIGHLY confusing. Declaring it in the
beginning makes sense, because you declare/initialize, then use it. But
using and *then* initializing it for the next iteration is kind of
quirky, because it breaks the logical encapsulation I would like to see
in *one* loop iteration.

/W

Hear, hear! to the declaration at the beginning. Just went through a
long bug search due to a similar behaviour. Terrible. I try to view
the body of a loop as if it were a separate function/method. If it
makes sense from that point of view, it will make sense in 3 months. I
mean, why would you want ot initialize something when you're done with it?

Cheers,
Rex

 

[Bruno Desthuilliers]

Hardy a écrit :

I experience a problem with append(). This is a part of my code:
for entity in temp:
md['module']= entity.addr.get('module')
md['id']=entity.addr.get('id')
md['type']=entity.addr.get('type')
#print md
mbusentities.append(md)
#print mbusentities
I want something like: [{'module': 'home', 'id': 123, 'type': 'core'},
{'module': 'work', 'id': 456, 'type': 'core'}]
md is always correct, BUT:mbusentities is wrong. Length of
mbusentities is same of temp, so it appended everything. BUT:
mbusentities only shows the values of the last append: [{'module':
'work', 'id': 456, 'type': 'core'}, {'module': 'work', 'id': 456,
'type': 'core'}]
What's wrong?

You're reusing the same "md" dictionary over and over, appending the
same object to the list each time. So what you have is a list of
references to the same dictionary. You need to set md = {} first
thing each iteration.

Thanks, that was my mistake, should take a break, getting code-blind

append = mbusentities.append
for entity in temp:
get = entity.addr.get
append(dict((k, get(k)) for k in ('module', 'id', 'type')))