pandas conditional statements and adding columns

Question

I am using Pandas to sort through an excel spreadsheet. I would like to execute an if/elif function to return a string in a new column within my dataframe. I am trying to return a new column named "action" that returns a string based off time values.

state     time      
 ca         1
 ca         5
 ca         7
 ca         10

for rows in df:

 if df[time]>=1:
    return "do nothing"

 elif df[time]<=5:
     return "add more"

 elif df[time]<=10:
      return "add less"

  else:
      return "error"

do you have a more specific question or error?

Lucas Hendren
– Lucas Hendren

2017-09-19 21:03:49 +00:00
Commented Sep 19, 2017 at 21:03 — Lucas Hendren
– Lucas Hendren, Commented Sep 19, 2017 at 21:03
please accept answers that solved your questions

JoYSword
– JoYSword

2017-10-08 14:45:54 +00:00
Commented Oct 8, 2017 at 14:45 — JoYSword
– JoYSword, Commented Oct 8, 2017 at 14:45

MaxU - stand with Ukraine · Accepted Answer · 2017-09-19 21:13:39Z

4

IIUC we can use pd.cut() method:

In [167]: df['new'] = pd.cut(df.time, 
                             bins=[-np.inf, 1, 5, 10, np.inf], 
                             labels=['do nothing','add more','add less','error'])

In [168]: df
Out[168]:
  state  time         new
0    ca     1  do nothing
1    ca     5    add more
2    ca     7    add less
3    ca    10    add less

edited Sep 19, 2017 at 21:13

answered Sep 19, 2017 at 21:03

MaxU - stand with Ukraine

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Comments

piRSquared · Accepted Answer · 2017-09-19 21:09:24Z

2

Using np.searchsorted

labels = np.array(['do nothing', 'add more', 'add less', 'error'])
df.assign(new=labels[np.searchsorted([1, 5, 10], df.time.values)])

  state  time         new
0    ca     1  do nothing
1    ca     5    add more
2    ca     7    add less
3    ca    10    add less

answered Sep 19, 2017 at 21:09

piRSquared

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Comments

Keiku · Accepted Answer · 2017-09-21 02:43:49Z

The following code is a simple way to add a column for each condition in pandas.

import pandas as pd
from io import StringIO

csv = StringIO("""state,time
ca,1
ca,5
ca,7
ca,10""")
df = pd.read_csv(csv)
# Out[1]:
#   state  time
# 0    ca           1
# 1    ca           5
# 2    ca           7
# 3    ca          10

def add_action(row):
    if row["time"] <= 1:
        return "do nothing"
    elif row["time"] <= 5:
        return "add more"
    elif row["time"] <= 10:
        return "add less"
    else:
        return "error"

df = df.assign(action=df.apply(add_action, axis=1))
# Out[2]: 
#   state  time      action
# 0    ca     1  do nothing
# 1    ca     5    add more
# 2    ca     7    add less
# 3    ca    10    add less

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