Add column to existing dataframe and import data into new column in Python Pandas

Question

I am reading a CSV file into a pandas dataframe using Python. I want to read in a list of text files into a new column of the dataframe.

The original CSV file I'm reading from looks like this:

Name,PrivateIP
bastion001,10.238.2.166
logicmonitor001,10.238.2.52
logicmonitor002,45.21.2.13

The original dataframe looks like this.

code:

hosts_list = dst = os.path.join('..', '..', 'source_files', 'aws_hosts_list', 'aws_hosts_list.csv')
fields = ["Name", "PrivateIP"]
orig_df = pd.read_csv(hosts_list, skipinitialspace=True, usecols=fields)
print(f"Orig DF: {orig_df}")

output:

Orig DF:
                       Name     PrivateIP
0               bastion001  10.238.2.166
1          logicmonitor001   10.238.2.52
2         logicmonitor002    45.21.2.13

The text directory has a bunch of text files in it with memory readings in each:

bastion001-memory.txt              B-mmp-rabbitmq-core002-memory.txt  logicmonitor002-memory.txt    mmp-cassandra001-memory.txt  company-division-rcsgw002-memory.txt
B-mmp-platsvc-core001-memory.txt   haproxy001-memory.txt              company-cassandra001-memory.txt  mmp-cassandra002-memory.txt  company-waepd001-memory.txt
B-mmp-platsvc-core002-memory.txt   haproxy002-memory.txt              company-cassandra002-memory.txt  mmp-cassandra003-memory.txt  company-waepd002-memory.txt
B-mmp-rabbitmq-core001-memory.txt  logicmonitor001-memory.txt         company-cassandra003-memory.txt  company-division-rcsgw001-memory.txt  company-waepd003-memory.txt

Each file looks similar to this:

cat haproxy001-memory.txt
7706172

I read each file into the existing dataframe.

rowcount == 0
text_path = '/home/tdun0002/stash/cloud_scripts/output_files/memory_stats/text/'
filelist = os.listdir(text_path)
for filename in filelist:
    if rowcount == 0:
        pass
    else:
        my_file = text_path + filename
        print(f"Adding {filename} to DF")
        try:
            orig_df = pd.update(my_file)
            print(f"Data Frame: {orif_df}")
            ++rowcount
        except Exception as e:
            print(f"An error has occurred: {e}")

But when I try to read the resulting dataframe again it has not been updated. I gave the new DF a new name for clarity.

code:

result_df = orig_df
pd.options.display.max_rows
print(f"\nResult Data Frame:\n{result_df}\n")

output:

Result Data Frame:
                      Name     PrivateIP
0               bastion001  10.238.2.166
1          logicmonitor001   10.238.2.52
2          logicmonitor002    45.21.2.13

How can I create a new column called Memory in the DF and add the contents of the text files to that column?

Gokturk Sahin · Accepted Answer · 2020-05-28 22:02:12Z

Here's the code I hope would work. It's a bit clunky, but you'll get the idea. There are comments inside.

import pandas as pd
import os
from os import listdir
from os.path import isfile, join

# get all files in the directory
# i used os.getcwd() to get the current directory
# if your text files are in another dir, then write exact dir location
# this gets you all files in your text dir
onlyfiles = [f for f in listdir(os.getcwd()) if isfile(join(os.getcwd(), f))]

# convert it to series
memory_series = pd.Series(onlyfiles)

# an apply function to get just txt files
# others will be returned as None
def file_name_getter(x):
    names = x.split(".", maxsplit=1)
    if names[1] == "txt":
        return names[0]
    else:
        return None

# apply the function and get a new series with name values
mem_list = memory_series.apply(lambda x: file_name_getter(x))

# now read first line of txt files
# and this is the function for it
def get_txt_data(x):
    if x != None:
        with open(f'{x}.txt') as f:
            return int(f.readline().rstrip())
    else:
        return 0

# apply the function, get a new series with memory values
mem_val_list = mem_list.apply(lambda x: get_txt_data(x))

# create a df where our Name and Memory data are present
# cast Memory data as int
df = pd.DataFrame(mem_val_list, columns=["Memory"], dtype="int")
df["Name"] = mem_list

# get rid of -memory now
def name_normalizer(x):
    if x is None:
        return x
    else:
        return x.rsplit("-", maxsplit=1)[0]

# apply function
df["Name"] = df["Name"].apply(lambda x:  name_normalizer(x))


# our sample orig_df
orig_df = pd.DataFrame([["algo_2", "10.10.10"], ["other", "20.20.20"]], columns=["Name", "PrivateIP"])

# merge using on, so if we miss data; that data wont cause any problem
# all matching names will get their memory values
final_df = orig_df.merge(df, on="Name")

edit: fixed Name to be returned correctly. (xxx-memory to xxx)

@bluethundr Just updated code, check it out! Forgot about your .txt files named as xxx-memory.txt

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