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What is the easiest way to push an element to the beginning of the array?
...f self, moving other elements upwards.
And in use:
irb>> a = [ 0, 1, 2]
=> [0, 1, 2]
irb>> a.unshift('x')
=> ["x", 0, 1, 2]
irb>> a.inspect
=> "["x", 0, 1, 2]"
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Efficient way to apply multiple filters to pandas DataFrame or Series
...numpy) allow for boolean indexing, which will be much more efficient:
In [11]: df.loc[df['col1'] >= 1, 'col1']
Out[11]:
1 1
2 2
Name: col1
In [12]: df[df['col1'] >= 1]
Out[12]:
col1 col2
1 1 11
2 2 12
In [13]: df[(df['col1'] >= 1) & (df['col1'] <=1 )]
Out...
Convert columns to string in Pandas
...will convert keys to valid json (and therefore 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 p...
How to drop columns by name in a data frame
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11 Answers
11
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How to find the length of a string in R
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See ?nchar. For example:
> nchar("foo")
[1] 3
> set.seed(10)
> strn <- paste(sample(LETTERS, 10), collapse = "")
> strn
[1] "NHKPBEFTLY"
> nchar(strn)
[1] 10
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How to count the number of true elements in a NumPy bool array
...:
>>> import numpy as np
>>> boolarr = np.array([[0, 0, 1], [1, 0, 1], [1, 0, 1]], dtype=np.bool)
>>> boolarr
array([[False, False, True],
[ True, False, True],
[ True, False, True]], dtype=bool)
>>> np.sum(boolarr)
5
Of course, that is a bool...
What's the difference between lists enclosed by square brackets and parentheses in Python?
...A list is mutable, meaning you can change its contents:
>>> x = [1,2]
>>> x.append(3)
>>> x
[1, 2, 3]
while tuples are not:
>>> x = (1,2)
>>> x
(1, 2)
>>> x.append(3)
Traceback (most recent call last):
File "<stdin>", line 1, in <m...
No provider for “framework:jasmine”! (Resolving: framework:jasmine)
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181
I had the same error after creating a new project the yeoman angular generator (yo angular).
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Switch to another Git tag
How do I check out version version/tag 1.1.4 of the rspec bundle ?
2 Answers
2
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