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Call apply-like function on each row of dataframe with multiple arguments from each row
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You can apply apply to a subset of the original data.
dat <- data.frame(x=c(1,2), y=c(3,4), z=c(5,6))
apply(dat[,c('x','z')], 1, function(x) sum(x) )
or if your function is just sum use the vectorized version:
rowSums(dat[,c('x','z')])
[1] 6 8...
Why does comparing strings using either '==' or 'is' sometimes produce a different result?
I've got a Python program where two variables are set to the value 'public' . In a conditional expression I have the comparison var1 is var2 which fails, but if I change it to var1 == var2 it returns True .
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Android View.getDrawingCache returns null, only null
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I was having this problem also and found this answer:
v.setDrawingCacheEnabled(true);
// this is the important code :)
// Without it the view will have a dimension of 0,0 and the bitmap will be null
v.measure(MeasureSpec.makeMeasure...
Get unique values from a list in python [duplicate]
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First declare your list properly, separated by commas. You can get the unique values by converting the list to a set.
mylist = ['nowplaying', 'PBS', 'PBS', 'nowplaying', 'job', 'debate', 'thenandnow']
myset = set(mylist)
print(myset)
If you use it further as a list,...
How to compare types
...eld and I want to know if it is System.String , System.DateTime , etc., but typeField.Equals(System.String) doesn't work.
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How do the post increment (i++) and pre increment (++i) operators work in Java?
... value and immediately returns it.
a++ also increments the value (in the background) but returns unchanged value of the variable - what looks like it is executed later.
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Difference between “!==” and “==!” [closed]
Yesterday I stumbled over this when I modified PHP code written by someone else. I was baffled that a simple comparison ( if ($var ==! " ") ) didn't work as expected. After some testing I realized that whoever wrote that code used ==! instead of !== as comparison operator. I've never seen ==! ...
lodash multi-column sortBy descending
There's a nifty method to sort an array of objects based on several properties:
7 Answers
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With arrays, why is it the case that a[5] == 5[a]?
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The C standard defines the [] operator as follows:
a[b] == *(a + b)
Therefore a[5] will evaluate to:
*(a + 5)
and 5[a] will evaluate to:
*(5 + a)
a is a pointer to the first element of the array. a[5] is the value that's 5 elements further from a, which is the same as *(...
How to wrap async function calls into a sync function in Node.js or Javascript?
Suppose you maintain a library that exposes a function getData . Your users call it to get actual data:
var output = getData();
Under the hood data is saved in a file so you implemented getData using Node.js built-in fs.readFileSync . It's obvious both getData and fs.readFileSync are sy...