[Solved:] How to use pd.append() ?

[ju21878436312]

Can someone tell me, why the first example of how to use pd.append() works, and the second not?

# 1) This works fine: 

df1 = pd.DataFrame([[1, 2], [3, 4]], columns=list('AB'))
df2 = pd.DataFrame([[5, 6], [7, 8]], columns=list('AB'))
df1.append(df2)
df1

# 2) However this does not work:

d3 = {'1':[100],'pos':["middle"]}
d4 = {'1':[200],'pos':["middle"]}

df3 = pd.DataFrame(data=d3)
df4 = pd.DataFrame(data=d4)

df3.append(df4)
df3

I am using the 2nd way to create my dataframe, and prefer to combine my dataframes with

pd.append() 

instead of

pd.concat()

[snippsat]

If save it in a variable it should work the same.

import pandas as pd

df1 = pd.DataFrame([[1, 2], [3, 4]], columns=list('AB'))
df2 = pd.DataFrame([[5, 6], [7, 8]], columns=list('AB'))
df_new1 = df1.append(df2)
print(df_new1)

d3 = {'1':[100],'pos':["middle"]}
d4 = {'1':[200],'pos':["middle"]}
df3 = pd.DataFrame(data=d3)
df4 = pd.DataFrame(data=d4)
df_new2 = df3.append(df4)
print(df_new2)

Output:
   A  B
0  1  2
1  3  4
0  5  6
1  7  8
     1     pos
0  100  middle
0  200  middle

[deanhystad]

This doesn't work either:

# 1) This works fine:   Oh no it doesn't!
 
df1 = pd.DataFrame([[1, 2], [3, 4]], columns=list('AB'))
df2 = pd.DataFrame([[5, 6], [7, 8]], columns=list('AB'))
df1.append(df2)
print(df1)

Output:
   A  B
0  1  2
1  3  4

In both cases .append() creates a new dataframe instead of modifying the dataframe in place.

[ju21878436312]

thank you!