/pandas 0.22

Comparison with R / R libraries

Since pandas aims to provide a lot of the data manipulation and analysis functionality that people use R for, this page was started to provide a more detailed look at the R language and its many third party libraries as they relate to pandas. In comparisons with R and CRAN libraries, we care about the following things:

  • Functionality / flexibility: what can/cannot be done with each tool
  • Performance: how fast are operations. Hard numbers/benchmarks are preferable
  • Ease-of-use: Is one tool easier/harder to use (you may have to be the judge of this, given side-by-side code comparisons)

This page is also here to offer a bit of a translation guide for users of these R packages.

For transfer of DataFrame objects from pandas to R, one option is to use HDF5 files, see External Compatibility for an example.

Quick Reference

We’ll start off with a quick reference guide pairing some common R operations using dplyr with pandas equivalents.

Querying, Filtering, Sampling

R pandas
dim(df) df.shape
head(df) df.head()
slice(df, 1:10) df.iloc[:9]
filter(df, col1 == 1, col2 == 1) df.query('col1 == 1 & col2 == 1')
df[df$col1 == 1 & df$col2 == 1,] df[(df.col1 == 1) & (df.col2 == 1)]
select(df, col1, col2) df[['col1', 'col2']]
select(df, col1:col3) df.loc[:, 'col1':'col3']
select(df, -(col1:col3)) df.drop(cols_to_drop, axis=1) but see [1]
distinct(select(df, col1)) df[['col1']].drop_duplicates()
distinct(select(df, col1, col2)) df[['col1', 'col2']].drop_duplicates()
sample_n(df, 10) df.sample(n=10)
sample_frac(df, 0.01) df.sample(frac=0.01)
[1] R’s shorthand for a subrange of columns (select(df, col1:col3)) can be approached cleanly in pandas, if you have the list of columns, for example df[cols[1:3]] or df.drop(cols[1:3]), but doing this by column name is a bit messy.


R pandas
arrange(df, col1, col2) df.sort_values(['col1', 'col2'])
arrange(df, desc(col1)) df.sort_values('col1', ascending=False)


R pandas
select(df, col_one = col1) df.rename(columns={'col1': 'col_one'})['col_one']
rename(df, col_one = col1) df.rename(columns={'col1': 'col_one'})
mutate(df, c=a-b) df.assign(c=df.a-df.b)

Grouping and Summarizing

R pandas
summary(df) df.describe()
gdf <- group_by(df, col1) gdf = df.groupby('col1')
summarise(gdf, avg=mean(col1, na.rm=TRUE)) df.groupby('col1').agg({'col1': 'mean'})
summarise(gdf, total=sum(col1)) df.groupby('col1').sum()

Base R

Slicing with R’s c

R makes it easy to access data.frame columns by name

df <- data.frame(a=rnorm(5), b=rnorm(5), c=rnorm(5), d=rnorm(5), e=rnorm(5))
df[, c("a", "c", "e")]

or by integer location

df <- data.frame(matrix(rnorm(1000), ncol=100))
df[, c(1:10, 25:30, 40, 50:100)]

Selecting multiple columns by name in pandas is straightforward

In [1]: df = pd.DataFrame(np.random.randn(10, 3), columns=list('abc'))

In [2]: df[['a', 'c']]
          a         c
0 -1.039575 -0.424972
1  0.567020 -1.087401
2 -0.673690 -1.478427
3  0.524988  0.577046
4 -1.715002 -0.370647
5 -1.157892  0.844885
6  1.075770  1.643563
7 -1.469388 -0.674600
8 -1.776904 -1.294524
9  0.413738 -0.472035

In [3]: df.loc[:, ['a', 'c']]

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