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Changing column names of a data frame
I have a data frame called "newprice" (see below) and I want to change the column names in my program in R.
16 Answers
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How to get object length [duplicate]
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This is actually worse than using a simple loop and counter because of the added overhead of the callback function.
– nullability
Feb 19 '13 at 17:35
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mongodb: insert if not exists
... has built-in support for this. Pass an extra parameter to your update() call: {upsert:true}. For example:
key = {'key':'value'}
data = {'key2':'value2', 'key3':'value3'};
coll.update(key, data, upsert=True); #In python upsert must be passed as a keyword argument
This replaces your if-find-els...
How to reverse apply a stash?
I have a small patch saved away in my git stash. I've applied it to my working copy using git stash apply . Now, I'd like to back out those changes by reverse applying the patch (kind of like what git revert would do but against the stash).
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How to tag an older commit in Git?
...epository, but we've made commits since then.
A tag at the beginning would allow us to "roll back" production to a known, stable state.
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NSString tokenize in Objective-C
...wered Jan 11 '09 at 11:54
Matt GallagherMatt Gallagher
14.4k22 gold badges3838 silver badges4141 bronze badges
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map vs. hash_map in C++
...tied to that key.
map is implemented as a balanced binary search tree (usually a red/black tree).
An unordered_map should give slightly better performance for accessing known elements of the collection, but a map will have additional useful characteristics (e.g. it is stored in sorted order, which...
What Makes a Good Unit Test? [closed]
...ng lots of automated tests and that you also have run into some common pitfalls when unit testing.
18 Answers
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Ignoring accented letters in string comparison
...for this, I wish I could upvote more than once! However, it doesn't handle all accented letters, for example ð, ħ and ø are not converted to o, h and o respectively. Is there any way to handle these as well?
– Avrohom Yisroel
Aug 2 '17 at 14:07
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Bytecode features not available in the Java language
...case of the invokespecial bytecode is handled for this class. It is set by all modern Java compilers (where "modern" is >= Java 1.1, if I remember correctly) and only ancient Java compilers produced class files where this was un-set. This flag exists only for backwards-compatibility reasons. Note...