
pandas DataFrame append: How to append or concatenate DataFrames and reindex
pandas DataFrame can be appended or concatenated by append
method like Python list.
import pandas
a = [
('Texas', 29),
('New York', 19),
]
b = [
('California', 40),
('Florida', 21),
]
df1 = pandas.DataFrame(a, columns=['State', 'Population'])
df2 = pandas.DataFrame(b, columns=['State', 'Population'])
df3 = df1.append(df2)
print(df1)
# State Population
# 0 Texas 29
# 1 New York 19
print(df2)
# State Population
# 0 California 40
# 1 Florida 21
print(df3)
# State Population
# 0 Texas 29
# 1 New York 19
# 0 California 40
# 1 Florida 21
df3 is simply df1 + df2 so the indexes of df3 are 0, 1, 0, 1, which no longer express the index of DataFrame. If you don't want those indexes and reindex, set ignore_index
option True
in the method.
import pandas
a = [
('Texas', 29),
('New York', 19),
]
b = [
('California', 40),
('Florida', 21),
]
df1 = pandas.DataFrame(a, columns=['State', 'Population'])
df2 = pandas.DataFrame(b, columns=['State', 'Population'])
df3 = df1.append(df2, ignore_index=True)
print(df3)
# State Population
# 0 Texas 29
# 1 New York 19
# 2 California 40
# 3 Florida 21
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