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“Large data” work flows using pandas
...going to append to each table by group
# we are not going to create indexes at this time
# but we *ARE* going to create (some) data_columns
# figure out the field groupings
for g, v in group_map.items():
# create the frame for this group
frame =...
How to break out from a ruby block?
...except in the case of lambdas):
def find(array, target)
array.each_with_index do |element,index|
return index if (element == target) # return from find
end
nil # If we didn't find the element, return nil
end
sh...
Get first n characters of a string
...f=strip_tags($str);
if(strlen($buff) > $n_chars)
{
$cut_index=strpos($buff,' ',$n_chars);
$buff=substr($buff,0,($cut_index===false? $n_chars: $cut_index+1)).$crop_str;
}
return $buff;
}
if $str is shorter than $n_chars returns it untouched.
If $str is equal to $...
In Python, how do I determine if an object is iterable?
...(o) will construct
an iterator that tries to fetch items from o by integer index, starting at index 0. The iterator will catch any IndexError (but no other errors) that is raised and then raises StopIteration itself.
In the most general sense, there's no way to check whether the iterator returned by...
What does character set and collation mean exactly?
...tion can help performance if your database uses the collation to create an index, and later uses that index to provide sorted results. However, since collation rules are often locale-specific, that index will be worthless if you need to sort results according to the rules of another locale.
...
JSON to pandas DataFrame
...dictionary to dataframe
train = pd.DataFrame.from_dict(dict_train, orient='index')
train.reset_index(level=0, inplace=True)
Hope it helps :)
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How do I print the elements of a C++ vector in GDB?
...ument print_vector
Display vector contents
Usage: print_vector VECTOR_NAME INDEX
VECTOR_NAME is the name of the vector
INDEX is an optional argument specifying the element to display
end
After restarting gdb (or sourcing ~/.gdbinit), show the associated help like this
gdb) help print_vector
Displ...
MySQL how to join tables on two fields
... Basically, slowness is because concrete calculates new values that has no indexes so direct conditions should be faster. if even this query would be slow again, check is indexes exists, and sometimes creation one index for 2 fields also makes sense.
– Eugene Kaurov
...
Javascript : natural sort of alphanumerical strings
...
once instead of in every step through the sort.
function naturalSort(ar, index){
var L= ar.length, i, who, next,
isi= typeof index== 'number',
rx= /(\.\d+)|(\d+(\.\d+)?)|([^\d.]+)|(\.(\D+|$))/g;
function nSort(aa, bb){
var a= aa[0], b= bb[0], a1, b1, i= 0, n, L= a.length...
How to calculate moving average using NumPy?
...y be is faster than FFT based methods:
EDIT Corrected an off-by-one wrong indexing spotted by Bean in the code. EDIT
def moving_average(a, n=3) :
ret = np.cumsum(a, dtype=float)
ret[n:] = ret[n:] - ret[:-n]
return ret[n - 1:] / n
>>> a = np.arange(20)
>>> moving_aver...