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Pandas copying wrong values - vmarg - Jan-05-2020
Can someone explain me this?
Python 3.7
pandas 0.25.3
import pandas as pd
foo = pd.concat([pd.DataFrame({'foo': [10,20]}), pd.DataFrame({'foo': [30,40]})])
bar = pd.DataFrame({'bar': [1, 2, 3, 4]})
foo["bar"] = bar["bar"]
print((foo["bar"].values == bar["bar"].values).all())
print(foo)Output:False
foo bar
0 10 1
1 20 2
0 30 1
1 40 2RE: Pandas copying wrong values - sandeep_ganga - Jan-06-2020
If we doesn't define ignore_index parameter, the concat/append will add second dataframe rows with the original index numbers it had, thus the new added rows have same index again which start with 0.
import pandas as pd
foo = pd.concat([pd.DataFrame({'foo': [10,20]}), pd.DataFrame({'foo': [30,40]})],ignore_index=True)
bar = pd.DataFrame({'bar': [1, 2, 3, 4]})
foo["bar"] = bar["bar"]
print((foo["bar"].values == bar["bar"].values).all())
print(foo)Output:True
foo bar
0 10 1
1 20 2
2 30 3
3 40 4Sandeep
GANGA SANDEEP KUMAR
RE: Pandas copying wrong values - vmarg - Jan-06-2020
Ok, thanks for the explenation.