create new column pandas based on condition code example

Example 1: make a condition statement on column pandas

df['color'] = ['red' if x == 'Z' else 'green' for x in df['Set']]

Example 2: pandas create new column conditional on other columns

# For creating new column with multiple conditions
conditions = [
    (df['Base Column 1'] == 'A') & (df['Base Column 2'] == 'B'),
    (df['Base Column 3'] == 'C')]
choices = ['Conditional Value 1', 'Conditional Value 2']
df['New Column'] = np.select(conditions, choices, default='Conditional Value 1')

Example 3: make a condition statement on column pandas

df.loc[df['column name'] condition, 'new column name'] = 'value if condition is met'

Example 4: add a value to an existing field in pandas dataframe after checking conditions

gapminder['gdpPercap_ind'] = gapminder.gdpPercap.apply(lambda x: 1 if x >= 1000 else 0)
gapminder.head()

Example 5: new column in pandas with where logic

virtsizes = {
  "type1": { "gb": 1.2, "xxx": 0, "yyy": 30 },
  "type2": { "gb": 1.5, "xxx": 2, "yyy": 20  },
  "type3": { "gb": 2.3, "xxx": 0.1, "yyy": 10  },
}
d = {k:v['gb'] for k,v in virtsizes.items()}
print (d)
{'type2': 1.5, 'type1': 1.2, 'type3': 2.3}

df = pd.DataFrame({'vol-type':['type1','type2']})
df["real_size"] = df["vol-type"].map(d)
print (df)
  vol-type  real_size
0    type1        1.2
1    type2        1.5