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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 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...
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) <...
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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Frequency table for a single variable
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153
Maybe .value_counts()?
>>> import pandas
>>> my_series = pandas.Series([1,2,2...
Replace all 0 values to NA
...me space for it. E.g.,
data.frame(x = c(1, NA, 2))
# x
# 1 1
# 2 NA
# 3 2
Also, the data frame structure requires all the columns to have the same number of elements so that there can be no "holes" (i.e., NULL values).
Now you could replace zeroes by NULL in a data frame in the sense of com...
The $.param( ) inverse function in JavaScript / jQuery
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answered Jun 9 '11 at 19:23
ccecce
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What is the bower (and npm) version syntax?
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342
In a nutshell, the syntax for Bower version numbers (and NPM's) is called SemVer, which is sho...
Get statistics for each group (such as count, mean, etc) using pandas GroupBy?
...t once. This should give you the result you need:
df[['col1', 'col2', 'col3', 'col4']].groupby(['col1', 'col2']).agg(['mean', 'count'])
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