CODEWITHSUNDEEP
pythonpandas
runningbirds
runningbirds

Reputation: 6615

Query local variables passed in loop using pandas query function

I want to be able to query each column name dynamically given the column names in a list. I can use the @sign to pass in dynamically on the other side of the equal sign but I'm really trying to do the columns dynamically..

import pandas as pd
import bumpy as np

df = pd.DataFrame(np.random.randn(10, 2), columns=list('ab'))
df

columns = ['a','b']

for each_column in columns:
    df.query("@each_column > 1")  ## error

Upvotes: 1

Views: 1467

Answers (1)

MaxU - stand with Ukraine
MaxU - stand with Ukraine

Reputation: 210832

IIUC:

In [12]: df
Out[12]:
          a         b
0 -0.272252 -0.467849
1 -0.221294 -2.583866
2 -0.117282  1.044487
3  0.451677 -0.434122
4  0.899038  0.712295
5  1.591961  0.031358
6 -1.398513 -0.600160
7  1.073948  1.348097
8 -1.016790 -0.773364
9 -0.628775  1.116282

dynamically generating a query:

In [13]: q = ' and '.join('{} > 1'.format(c) for c in df.columns)

In [14]: q
Out[14]: 'a > 1 and b > 1'

In [15]: df.query(q)
Out[15]:
          a         b
7  1.073948  1.348097

Upvotes: 1

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