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What's the fastest way to merge/join data.frames in R?
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DF1 = data.frame(a = c(1, 1, 2, 2), b = 1:4)
DF2 = data.frame(b = c(1, 2, 3, 3, 4), c = letters[1:5])
merge(DF1, DF2)
b a c
1 1 1 a
2 2 1 b
3 3 2 c
4 3 2 d
5 4 2 e
DF1$c = DF2$c[match(DF1$b, DF2$b)]
DF1$c
[1] a b c e
Levels: a b c d e
> DF1
a b c
1 1 1 a
2 1 2 b
3 2 3 c
4 2 4 e
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How to use a decimal range() step value?
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33 Answers
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how to convert array values from string to int?
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edited Apr 23 '19 at 10:46
Rahul
16.8k77 gold badges3434 silver badges5353 bronze badges
a...
Output data from all columns in a dataframe in pandas [duplicate]
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Erel Segal-Halevi
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answered Nov 5 '12 at 18:13
YarivYariv
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Drop rows with all zeros in pandas data frame
...0,1,0,1]})
> df = df[(df.T != 0).any()]
> df
a b
1 0 1
2 1 0
3 1 1
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How to select rows from a DataFrame based on column values?
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4135
To select rows whose column value equals a scalar, some_value, use ==:
df.loc[df['column_name'...
Difference between map, applymap and apply methods in Pandas
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Straight from Wes McKinney's Python for Data Analysis book, pg. 132 (I highly recommended this book):
Another frequent operation is applying a function on 1D arrays to each column or row. DataFrame’s apply method does exactly this:
In [116]: frame = DataFrame(np.random.randn(4, 3),...
Regular expression for matching latitude/longitude coordinates?
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Miha_x64
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answered Aug 19 '10 at 3:38
Eric CEric C
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Why does (0 < 5 < 3) return true?
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443
Order of operations causes (0 < 5 < 3) to be interpreted in javascript as ((0 < 5) <...
Convert floats to ints in Pandas?
...f= pd.DataFrame(range(5), columns=['a'])
df.a = df.a.astype(float)
df
Out[33]:
a
0 0.0000000
1 1.0000000
2 2.0000000
3 3.0000000
4 4.0000000
pd.options.display.float_format = '{:,.0f}'.format
df
Out[35]:
a
0 0
1 1
2 2
3 3
4 4
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