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How to select the row with the maximum value in each group
...solution:
require(data.table) ## 1.9.2
group <- as.data.table(group)
If you want to keep all the entries corresponding to max values of pt within each group:
group[group[, .I[pt == max(pt)], by=Subject]$V1]
# Subject pt Event
# 1: 1 5 2
# 2: 2 17 2
# 3: 3 5 ...
“ValueError: zero length field name in format” error in Python 3.0,3.1,3.2
I'm trying learn Python (3 to be more specific) and I'm getting this error:
3 Answers
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Pythonic way of checking if a condition holds for any element of a list
I have a list in Python, and I want to check if any elements are negative. Specman has the has() method for lists which does:
...
Reordering arrays
...
If you know the indexes you could easily swap the elements, with a simple function like this:
function swapElement(array, indexA, indexB) {
var tmp = array[indexA];
array[indexA] = array[indexB];
array[indexB] = tmp;
}...
multiprocessing: sharing a large read-only object between processes?
...My processes aren't really fitlers; they're all the same, just processing different pieces of data.
– Parand
Mar 18 '09 at 20:20
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C dynamically growing array
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I can use pointers, but I am a bit afraid of using them.
If you need a dynamic array, you can't escape pointers. Why are you afraid though? They won't bite (as long as you're careful, that is). There's no built-in dynamic array in C, you'll just have to write one yourself. In C++, ...
How to limit UITableView row reordering to a section
...exPath toProposedIndexPath:(NSIndexPath *)proposedDestinationIndexPath
{
if (sourceIndexPath.section != proposedDestinationIndexPath.section) {
NSInteger row = 0;
if (sourceIndexPath.section < proposedDestinationIndexPath.section) {
row = [tableView numberOfRowsInSection:sourceInd...
MySQL load NULL values from CSV data
...field into a local variable, and then sets the actual field value to NULL, if the local variable ends up containing an empty string:
LOAD DATA INFILE '/tmp/testdata.txt'
INTO TABLE moo
FIELDS TERMINATED BY ","
LINES TERMINATED BY "\n"
(one, two, three, @vfour, five)
SET four = NULLIF(@vfour,'')
;
...
Is there an “exists” function for jQuery?
..., and for numbers 0 means false, everything else true. So you could write:
if ($(selector).length)
You don't need that >0 part.
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Accessing bash command line args $@ vs $*
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The difference appears when the special parameters are quoted. Let me illustrate the differences:
$ set -- "arg 1" "arg 2" "arg 3"
$ for word in $*; do echo "$word"; done
arg
1
arg
2
arg
3
$ for word in $@; do echo "$word"; ...