Rearranging columns with pandas: Is there an equivalent to dplyr's select(..., everything())?

user_8605348 0
Viewed 547

I'm trying to rearrange columns in a DataFrame, by putting a few columns first, and then all the others after.

With R's dplyr, this would look like:

library(dplyr)

df = tibble(col1 = c("a", "b", "c"),
            id = c(1, 2, 3),
            col2 = c(2, 4, 6),
            date = c("1 Feb", "2 Feb", "3 Feb"))

df2 = select(df,
             id, date, everything())

Easy. With Python's pandas, here's what I've tried:

import pandas as pd

df = pd.DataFrame({
    "col1": ["a", "b", "c"],
    "id": [1, 2, 3],
    "col2": [2, 4, 6],
    "date": ["1 Feb", "2 Feb", "3 Feb"]
    })

# using sets
cols = df.columns.tolist()
cols_1st = {"id", "date"}
cols = set(cols) - cols_1st
cols = list(cols_1st) + list(cols)

# wrong column order
df2 = df[cols]

# using lists
cols = df.columns.tolist()
cols_1st = ["id", "date"]
cols = [c for c in cols if c not in cols_1st]
cols = cols_1st + cols

# right column order, but is there a better way?
df3 = df[cols]

The pandas way is more tedious, but I'm fairly new to this. Is there a better way?

dplyr pandas dataframe r python
3 Answers

You can use df.drop:

>>> df = pd.DataFrame({
    "col1": ["a", "b", "c"],
    "id": [1, 2, 3],
    "col2": [2, 4, 6],
    "date": ["1 Feb", "2 Feb", "3 Feb"]
    })

>>> df

  col1  id  col2   date
0    a   1     2  1 Feb
1    b   2     4  2 Feb
2    c   3     6  3 Feb

>>> cols_1st = ["id", "date"]

>>> df[cols_1st + list(df.drop(cols_1st, 1))]

   id   date col1  col2
0   1  1 Feb    a     2
1   2  2 Feb    b     4
2   3  3 Feb    c     6
user_54317910

Usually, the best translation between R and Python Pandas is with base R which follow the same semantics such as logical indexing on a vector, here being column names. Notice the similarity below with negation and in functions:

# R 
mycols <- c("id", "date")
df2 <- df[c(mycols, colnames(df)[!colnames(df) %in% c(mycols)])]


# PANDAS (OLDER, NON-RECOMMENDED WAY)
mycols = ["id", "date"]
df2 = df[mycols + df.columns[~df.columns.isin(mycols)].tolist()]

# PANDAS (CURRENT, RECOMMENDED WAY WITH reindex)
df2 = df.reindex(mycols + df.columns[~df.columns.isin(mycols)].tolist(),
                 axis='columns')
user_14224510

As easy as you do it in R with datar:

>>> from datar.all import c, f, tibble, select, everything
>>> df = tibble(col1 = c("a", "b", "c"),
...             id = c(1, 2, 3),
...             col2 = c(2, 4, 6),
...             date = c("1 Feb", "2 Feb", "3 Feb"))
>>>             
>>> df2 = select(df,
...              f.id, f.date, everything())
>>>              
>>> df2
       id     date     col1    col2
  <int64> <object> <object> <int64>
0       1    1 Feb        a       2
1       2    2 Feb        b       4
2       3    3 Feb        c       6

I am the author of the package. Feel free to submit issues if you have any questions.

user_50881650
Related