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How to check whether a pandas DataFrame is empty?
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I use the len function. It's much faster than empty. len(df.index) is even faster.
import pandas as pd
import numpy as np
df = pd.DataFrame(np.random.randn(10000, 4), columns=list('ABCD'))
def empty(df):
return df.empty
def lenz(df):
return len(df) == 0
def lenzi(df):
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Update a dataframe in pandas while iterating row by row
...ot on the value from the iterator. The iterator value is only used for the index of the value/object. What will fail is row['ifor']=some_thing, for the reasons mentioned in the documentation.
– rakke
May 11 '16 at 12:32
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Create a .csv file with values from a Python list
...ame(data={"col1": list_1, "col2": list_2})
df.to_csv("./file.csv", sep=',',index=False)
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Finding all possible permutations of a given string in python
...ing_copy = [character for character in string]
# swap the current index with the step
string_copy[step], string_copy[i] = string_copy[i], string_copy[step]
# recurse on the portion of the string that has not been swapped yet (now it's index will begin with step + 1)
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How can you determine how much disk space a particular MySQL table is taking up?
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For a table mydb.mytable run this for:
BYTES
SELECT (data_length+index_length) tablesize
FROM information_schema.tables
WHERE table_schema='mydb' and table_name='mytable';
KILOBYTES
SELECT (data_length+index_length)/power(1024,1) tablesize_kb
FROM information_schema.tables
WHERE table_s...
Regular expression \p{L} and \p{N}
...This syntax is specific for modern Unicode regex implementation, which not all interpreters recognize. You can safely replace \p{L} by {a-zA-Z} (ascii notation) or {\w} (perl/vim notation); and \p{N} by {0-9} (ascii) or {\d} (perl/vim). If you want to match all of them, just do: {a-zA-Z0-9}+ or {\w\...
How to make button look like a link?
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If you don't want all buttons to be styled as links, scope the style with something like button.link {...styles...} then <button class="link">Your button</button>. This also avoids using !important which is always a good idea.
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Typical AngularJS workflow and project structure (with Python Flask)
...templates and stay away from server-side templates. Using render_template('index.html') will cause Flask to interpret your angular templates as jinja templates, so they won't render correctly. Instead, you'll want to do the following:
@app.route("/")
def index():
return send_file('templates/ind...
How to get the size of a JavaScript object?
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Anyone who landed here looking for the smallest type for the purposes of false/true, it seems to be undefined/null.
– zupa
Jan 24 '13 at 16:32
3
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Efficient way to apply multiple filters to pandas DataFrame or Series
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Pandas (and 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[(d...