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Drop unused factor levels in a subsetted data frame
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> subdf$letters
[1] a b c
Levels: a b c
EDIT
From the factor page example:
factor(ff) # drops the levels that do not occur
For dropping levels from all factor columns in a dataframe, you can use:
subdf <- subset(df, numbers <= 3)
subdf[] <- lapply(subdf, function(x) if(is.fa...
How do I break out of nested loops in Java?
...tion can be met.
You can use break with a label for the outer loop. For example:
public class Test {
public static void main(String[] args) {
outerloop:
for (int i=0; i < 5; i++) {
for (int j=0; j < 5; j++) {
if (i * j > 6) {
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pythonic way to do something N times without an index variable?
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A slightly faster approach than looping on xrange(N) is:
import itertools
for _ in itertools.repeat(None, N):
do_something()
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iReport not starting using JRE 8
I have downloaded and installed the iReport 4.5 using te Windows installer. But when I try to start the iReport it shows the splash screen but does not start.
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How would one write object-oriented code in C? [closed]
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The proper collection (Book + source-code examples) is available from this rit.edu index Object oriented programming with ANSI-C
– David C. Rankin
Sep 2 '14 at 8:59
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How to generate random number with the specific length in python
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To get a random 3-digit number:
from random import randint
randint(100, 999) # randint is inclusive at both ends
(assuming you really meant three digits, rather than "up to three digits".)
To use an arbitrary number of digits:
from random import randin...
Java project in Eclipse: The type java.lang.Object cannot be resolved. It is indirectly referenced f
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In my case it occurred because i have accidentally removed the JRE while importing the project [my fault]. This gave me a clue to fix the issue.
– GayashanNA
Apr 22 '14 at 6:50
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How do I write a short literal in C++?
...rt enough to compile this as if it's a short literal (i.e. it wouldn't actually allocate an int and then cast it every time).
The following illustrates how much you should worry about this:
a = 2L;
b = 2.0;
c = (short)2;
d = '\2';
Compile -> disassemble ->
movl $2, _a
movl $2, _b
m...
Removing path and extension from filename in powershell
I have a series of strings which are full paths to files. I'd like to save just the filename, without the file extension and the leading path. So from this:
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Error: The processing instruction target matching “[xX][mM][lL]” is not allowed
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For PHP, put this line of code before you start printing your XML:
while(ob_get_level()) ob_end_clean();
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