dataframe select rows by condition code example

Example 1: fetch row where column is equal to a value pandas

df.loc[df['column_name'] == 'value']

Example 2: only keep rows of a dataframe based on a column value

df.loc[df['column_name'] == some_value]

Example 3: new dataframe based on certain row conditions

filterinfDataframe = dfObj[(dfObj['Sale'] > 30) & (dfObj['Sale'] < 33) ]

Example 4: new dataframe based on certain row conditions

# Create variable with TRUE if nationality is USA
american = df['nationality'] == "USA"

# Create variable with TRUE if age is greater than 50
elderly = df['age'] > 50

# Select all cases where nationality is USA and age is greater than 50
df[american & elderly]

Example 5: python pandas dataframe conditional subset

In [722]: df[(df['C']==1) | df['B']]
Out[722]:
   A      B  C
0  1   True  1
2  2  False  1
3  2   True  2
4  3   True  1

In [723]: df.query('C==1 or B==True')
Out[723]:
   A      B  C
0  1   True  1
2  2  False  1
3  2   True  2
4  3   True  1

In [724]: df[df.eval('C==1 or B==True')]
Out[724]:
   A      B  C
0  1   True  1
2  2  False  1
3  2   True  2
4  3   True  1