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Efficient way to apply multiple filters to pandas DataFrame or Series
...ite helper functions for this, consider something along these lines:
In [14]: def b(x, col, op, n):
return op(x[col],n)
In [15]: def f(x, *b):
return x[(np.logical_and(*b))]
In [16]: b1 = b(df, 'col1', ge, 1)
In [17]: b2 = b(df, 'col1', le, 1)
In [18]: f(df, b1, b2)
O...
Convert columns to string in Pandas
...refore your keys to strings):
In [11]: df = pd.DataFrame([['A', 2], ['A', 4], ['B', 6]])
In [12]: df.to_json()
Out[12]: '{"0":{"0":"A","1":"A","2":"B"},"1":{"0":2,"1":4,"2":6}}'
In [13]: df[0].to_json()
Out[13]: '{"0":"A","1":"A","2":"B"}'
Note: you can pass in a buffer/file to save this to, al...
How to drop columns by name in a data frame
... function. For example :
R> df <- data.frame(x=1:5, y=2:6, z=3:7, u=4:8)
R> df
x y z u
1 1 2 3 4
2 2 3 4 5
3 3 4 5 6
4 4 5 6 7
5 5 6 7 8
Then you can use the which function and the - operator in column indexation :
R> df[ , -which(names(df) %in% c("z","u"))]
x y
1 1 2
2 2 3
3 3 4...
How to find the length of a string in R
...
424
See ?nchar. For example:
> nchar("foo")
[1] 3
> set.seed(10)
> strn <- paste(samp...
How to count the number of true elements in a NumPy bool array
...erDavid Alber
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2
...
What's the difference between lists enclosed by square brackets and parentheses in Python?
... = {}
>>> z[x] = 3
>>> z
{(1, 2): 3}
>>> z[y] = 4
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'
Note that, as many people have pointed out, you can add tuples together. For example:
>>>...
efficient circular buffer?
...range(20):
... d.append(i)
...
>>> d
deque([10, 11, 12, 13, 14, 15, 16, 17, 18, 19], maxlen=10)
There is a recipe in the docs for deque that is similar to what you want. My assertion that it's the most efficient rests entirely on the fact that it's implemented in C by an incredibly s...
How to randomize (or permute) a dataframe rowwise and columnwise?
...
234
Given the R data.frame:
> df1
a b c
1 1 1 0
2 1 0 0
3 0 1 0
4 0 0 0
Shuffle row-wise:
&...
No provider for “framework:jasmine”! (Resolving: framework:jasmine)
...n": "0.0.0",
"dependencies": {},
"devDependencies": {
"grunt": "~0.4.1",
"grunt-autoprefixer": "~0.4.0",
"grunt-bower-install": "~0.7.0",
"grunt-concurrent": "~0.4.1",
"grunt-contrib-clean": "~0.5.0",
"grunt-contrib-coffee": "~0.7.0",
"grunt-contrib-compass": "~0.6.0"...
Creating Multifield Indexes in Mongoose / MongoDB
...
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