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How do I get the object if it exists, or None if it does not exist?
... python is to wrap it in a try catch:
try:
go = SomeModel.objects.get(foo='bar')
except SomeModel.DoesNotExist:
go = None
What I did do, is to subclass models.Manager, create a safe_get like the code above and use that manager for my models. That way you can write: SomeModel.objects.safe_...
Find integer index of rows with NaN in pandas dataframe
...
And just in case, if you want to find the coordinates of 'nan' for all the columns instead (supposing they are all numericals), here you go:
df = pd.DataFrame([[0,1,3,4,np.nan,2],[3,5,6,np.nan,3,3]])
df
0 1 2 3 4 5
0 0 1 3 4.0 NaN 2
1 3 5 6 NaN 3.0 3
np.where(np.as...
What do Clustered and Non clustered index actually mean?
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With a clustered index the rows are stored physically on the disk in the same order as the index. Therefore, there can be only one clustered index.
With a non clustered index there is a second list that has pointers to the physical rows. You can have many non clustered ind...
How do I clone a Django model instance object and save it to the database?
...imary key of your object and run save().
obj = Foo.objects.get(pk=<some_existing_pk>)
obj.pk = None
obj.save()
If you want auto-generated key, set the new key to None.
More on UPDATE/INSERT here.
Official docs on copying model instances: https://docs.djangoproject.com/en/2.2/topics/db/que...
How to disable / enable dialog negative positive buttons?
...ertDialog.Builder(MainActivity.this);
builder.setIcon(android.R.drawable.ic_dialog_info);
builder.setTitle("Alert dialog title");
builder.setMessage("This is the example code snippet to disable button if edittext attached to dialog is empty.");
builder.setPositiveButton("PositiveButton",
new...
Prevent errors from breaking / crashing gulp watch
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Your swallowError function should look like this:
function swallowError (error) {
// If you want details of the error in the console
console.log(error.toString())
this.emit('end')
}
I think you have to bind this function ...
git diff two files on same branch, same commit
... but the fact that he mentions BeyondCompare implies that he's not specifically looking for a git diff but simply an easy to read diff. Also the fact he accepted my answer as what he was looking for also indicates that it does in fact answer it.
– JaredMcAteer
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How to merge images in command line? [closed]
...g lots of PNGs means to decode them (to a pixmap) for the operation and finally encode them again. If you want to extend an existing sprite very often, then maybe keeping the decoded pixmap versions can speed up things. See my answer for doing it using the PNM tools to achieve this operation. But...
How to know what the 'errno' means?
When calling execl(...) , I get an errno=2 . What does it mean? How can I know the meaning of this errno ?
15 Answers
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Setup RSpec to test a gem (not Rails)
...my_gem ) to setup the structure for the new gem and edit the *.gemspec manually.
I also added s.add_development_dependency "rspec", ">= 2.0.0" to gemspec and did a bundle install .
...