Practical Business Python

Taking care of business, one python script at a time

Sun 30 November 2014

Common Excel Tasks Demonstrated in Pandas

Posted by Chris Moffitt in articles   

Introduction

The purpose of this article is to show some common Excel tasks and how you would execute similar tasks in pandas. Some of the examples are somewhat trivial but I think it is important to show the simple as well as the more complex functions you can find elsewhere. As an added bonus, I’m going to do some fuzzy string matching to show a little twist to the process and show how pandas can utilize the full python system of modules to do something simply in python that would be complex in Excel.

Make sense? Let’s get started.

Adding a Sum to a Row

The first task I’ll cover is summing some columns to add a total column.

We will start by importing our excel data into a pandas dataframe.

import pandas as pd
import numpy as np
df = pd.read_excel("excel-comp-data.xlsx")
df.head()
account name street city state postal-code Jan Feb Mar
0 211829 Kerluke, Koepp and Hilpert 34456 Sean Highway New Jaycob Texas 28752 10000 62000 35000
1 320563 Walter-Trantow 1311 Alvis Tunnel Port Khadijah NorthCarolina 38365 95000 45000 35000
2 648336 Bashirian, Kunde and Price 62184 Schamberger Underpass Apt. 231 New Lilianland Iowa 76517 91000 120000 35000
3 109996 D’Amore, Gleichner and Bode 155 Fadel Crescent Apt. 144 Hyattburgh Maine 46021 45000 120000 10000
4 121213 Bauch-Goldner 7274 Marissa Common Shanahanchester California 49681 162000 120000 35000

We want to add a total column to show total sales for Jan, Feb and Mar.

This is straightforward in Excel and in pandas. For Excel, I have added the formula sum(G2:I2) in column J. Here is what it looks like in Excel:

Excel sum example

Next, here is how we do it in pandas:

df["total"] = df["Jan"] + df["Feb"] + df["Mar"]
df.head()
account name street city state postal-code Jan Feb Mar total
0 211829 Kerluke, Koepp and Hilpert 34456 Sean Highway New Jaycob Texas 28752 10000 62000 35000 107000
1 320563 Walter-Trantow 1311 Alvis Tunnel Port Khadijah NorthCarolina 38365 95000 45000 35000 175000
2 648336 Bashirian, Kunde and Price 62184 Schamberger Underpass Apt. 231 New Lilianland Iowa 76517 91000 120000 35000 246000
3 109996 D’Amore, Gleichner and Bode 155 Fadel Crescent Apt. 144 Hyattburgh Maine 46021 45000 120000 10000 175000
4 121213 Bauch-Goldner 7274 Marissa Common Shanahanchester California 49681 162000 120000 35000 317000

Next, let’s get some totals and other values for each month. Here is what we are trying to do as shown in Excel:

Excel sum example 2

As you can see, we added a SUM(G2:G16) in row 17 in each of the columns to get totals by month.

Performing column level analysis is easy in pandas. Here are a couple of examples.

df["Jan"].sum(), df["Jan"].mean(),df["Jan"].min(),df["Jan"].max()
(1462000, 97466.666666666672, 10000, 162000)

Now, we want to add a total by month and grand total. This is where pandas and Excel diverge a little. It is very simple to add totals in cells in Excel for each month. Because pandas need to maintain the integrity of the entire DataFrame, there are a couple more steps.

First, create a sum for the month and total columns.

sum_row=df[["Jan","Feb","Mar","total"]].sum()
sum_row
Jan      1462000
Feb      1507000
Mar       717000
total    3686000
dtype: int64

This is fairly intuitive however, if you want to add totals as a row, you need to do some minor manipulations.

We need to transpose the data and convert the Series to a DataFrame so that it is easier to concat onto our existing data. The T function allows us to switch the data from being row-based to column-based.

df_sum=pd.DataFrame(data=sum_row).T
df_sum
Jan Feb Mar total
0 1462000 1507000 717000 3686000

The final thing we need to do before adding the totals back is to add the missing columns. We use reindex to do this for us. The trick is to add all of our columns and then allow pandas to fill in the values that are missing.

df_sum=df_sum.reindex(columns=df.columns)
df_sum
account name street city state postal-code Jan Feb Mar total
0 NaN NaN NaN NaN NaN NaN 1462000 1507000 717000 3686000

Now that we have a nicely formatted DataFrame, we can add it to our existing one using append .

df_final=df.append(df_sum,ignore_index=True)
df_final.tail()
account name street city state postal-code Jan Feb Mar total
11 231907 Hahn-Moore 18115 Olivine Throughway Norbertomouth NorthDakota 31415 150000 10000 162000 322000
12 242368 Frami, Anderson and Donnelly 182 Bertie Road East Davian Iowa 72686 162000 120000 35000 317000
13 268755 Walsh-Haley 2624 Beatty Parkways Goodwinmouth RhodeIsland 31919 55000 120000 35000 210000
14 273274 McDermott PLC 8917 Bergstrom Meadow Kathryneborough Delaware 27933 150000 120000 70000 340000
15 NaN NaN NaN NaN NaN NaN 1462000 1507000 717000 3686000

Additional Data Transforms

For another example, let’s try to add a state abbreviation to the data set.

From an Excel perspective the easiest way is probably to add a new column, do a vlookup on the state name and fill in the abbreviation.

I did this and here is a snapshot of what the results looks like:

Excel vlookup example

You’ll notice that after performing the vlookup, there are some values that are not coming through correctly. That’s because we misspelled some of the states. Handling this in Excel would be really challenging (on big data sets).

Fortunately with pandas we have the full power of the python ecosystem at our disposal. In thinking about how to solve this type of messy data problem, I thought about trying to do some fuzzy text matching to determine the correct value.

Fortunately someone else has done a lot of work in this are. The fuzzy wuzzy library has some pretty useful functions for this type of situation. Make sure to get it and install it first.

The other piece of code we need is a state name to abbreviation mapping. Instead of trying to type it myself, a little googling found this code.

Get started by importing the appropriate fuzzywuzzy functions and define our state map dictionary.

from fuzzywuzzy import fuzz
from fuzzywuzzy import process
state_to_code = {"VERMONT": "VT", "GEORGIA": "GA", "IOWA": "IA", "Armed Forces Pacific": "AP", "GUAM": "GU",
                 "KANSAS": "KS", "FLORIDA": "FL", "AMERICAN SAMOA": "AS", "NORTH CAROLINA": "NC", "HAWAII": "HI",
                 "NEW YORK": "NY", "CALIFORNIA": "CA", "ALABAMA": "AL", "IDAHO": "ID", "FEDERATED STATES OF MICRONESIA": "FM",
                 "Armed Forces Americas": "AA", "DELAWARE": "DE", "ALASKA": "AK", "ILLINOIS": "IL",
                 "Armed Forces Africa": "AE", "SOUTH DAKOTA": "SD", "CONNECTICUT": "CT", "MONTANA": "MT", "MASSACHUSETTS": "MA",
                 "PUERTO RICO": "PR", "Armed Forces Canada": "AE", "NEW HAMPSHIRE": "NH", "MARYLAND": "MD", "NEW MEXICO": "NM",
                 "MISSISSIPPI": "MS", "TENNESSEE": "TN", "PALAU": "PW", "COLORADO": "CO", "Armed Forces Middle East": "AE",
                 "NEW JERSEY": "NJ", "UTAH": "UT", "MICHIGAN": "MI", "WEST VIRGINIA": "WV", "WASHINGTON": "WA",
                 "MINNESOTA": "MN", "OREGON": "OR", "VIRGINIA": "VA", "VIRGIN ISLANDS": "VI", "MARSHALL ISLANDS": "MH",
                 "WYOMING": "WY", "OHIO": "OH", "SOUTH CAROLINA": "SC", "INDIANA": "IN", "NEVADA": "NV", "LOUISIANA": "LA",
                 "NORTHERN MARIANA ISLANDS": "MP", "NEBRASKA": "NE", "ARIZONA": "AZ", "WISCONSIN": "WI", "NORTH DAKOTA": "ND",
                 "Armed Forces Europe": "AE", "PENNSYLVANIA": "PA", "OKLAHOMA": "OK", "KENTUCKY": "KY", "RHODE ISLAND": "RI",
                 "DISTRICT OF COLUMBIA": "DC", "ARKANSAS": "AR", "MISSOURI": "MO", "TEXAS": "TX", "MAINE": "ME"}

Here are some example of how the fuzzy text matching function works.

process.extractOne("Minnesotta",choices=state_to_code.keys())
('MINNESOTA', 95)
process.extractOne("AlaBAMMazzz",choices=state_to_code.keys(),score_cutoff=80)

Now that we know how this works, we create our function to take the state column and convert it to a valid abbreviation. We use the 80 score_cutoff for this data. You can play with it to see what number works for your data. You’ll notice that we either return a valid abbreviation or an np.nan so that we have some valid values in the field.

def convert_state(row):
    abbrev = process.extractOne(row["state"],choices=state_to_code.keys(),score_cutoff=80)
    if abbrev:
        return state_to_code[abbrev[0]]
    return np.nan

Add the column in the location we want and fill it with NaN values

df_final.insert(6, "abbrev", np.nan)
df_final.head()
account name street city state postal-code abbrev Jan Feb Mar total
0 211829 Kerluke, Koepp and Hilpert 34456 Sean Highway New Jaycob Texas 28752 NaN 10000 62000 35000 107000
1 320563 Walter-Trantow 1311 Alvis Tunnel Port Khadijah NorthCarolina 38365 NaN 95000 45000 35000 175000
2 648336 Bashirian, Kunde and Price 62184 Schamberger Underpass Apt. 231 New Lilianland Iowa 76517 NaN 91000 120000 35000 246000
3 109996 D’Amore, Gleichner and Bode 155 Fadel Crescent Apt. 144 Hyattburgh Maine 46021 NaN 45000 120000 10000 175000
4 121213 Bauch-Goldner 7274 Marissa Common Shanahanchester California 49681 NaN 162000 120000 35000 317000

We use apply to add the abbreviations into the approriate column.

df_final['abbrev'] = df_final.apply(convert_state, axis=1)
df_final.tail()
account name street city state postal-code abbrev Jan Feb Mar total
11 231907 Hahn-Moore 18115 Olivine Throughway Norbertomouth NorthDakota 31415 ND 150000 10000 162000 322000
12 242368 Frami, Anderson and Donnelly 182 Bertie Road East Davian Iowa 72686 IA 162000 120000 35000 317000
13 268755 Walsh-Haley 2624 Beatty Parkways Goodwinmouth RhodeIsland 31919 RI 55000 120000 35000 210000
14 273274 McDermott PLC 8917 Bergstrom Meadow Kathryneborough Delaware 27933 DE 150000 120000 70000 340000
15 NaN NaN NaN NaN NaN NaN NaN 1462000 1507000 717000 3686000

I think this is pretty cool. We have developed a very simple process to intelligently clean up this data. Obviously when you only have 15 or so rows, this is not a big deal. However, what if you had 15,000? You would have to do something manual in Excel to clean this up.

Subtotals

For the final section of this article, let’s get some subtotals by state.

In Excel, we would use the subtotal tool to do this for us.

Excel vlookup example

The output would look like this:

Excel vlookup example

Creating a subtotal in pandas, is accomplished using groupby

df_sub=df_final[["abbrev","Jan","Feb","Mar","total"]].groupby('abbrev').sum()
df_sub
Jan Feb Mar total
abbrev
AR 150000 120000 35000 305000
CA 162000 120000 35000 317000
DE 150000 120000 70000 340000
IA 253000 240000 70000 563000
ID 70000 120000 35000 225000
ME 45000 120000 10000 175000
MS 62000 120000 70000 252000
NC 95000 45000 35000 175000
ND 150000 10000 162000 322000
PA 70000 95000 35000 200000
RI 200000 215000 70000 485000
TN 45000 120000 55000 220000
TX 10000 62000 35000 107000

Next, we want to format the data as currency by using applymap to all the values in the data frame.

def money(x):
    return "${:,.0f}".format(x)

formatted_df = df_sub.applymap(money)
formatted_df
Jan Feb Mar total
abbrev
AR $150,000 $120,000 $35,000 $305,000
CA $162,000 $120,000 $35,000 $317,000
DE $150,000 $120,000 $70,000 $340,000
IA $253,000 $240,000 $70,000 $563,000
ID $70,000 $120,000 $35,000 $225,000
ME $45,000 $120,000 $10,000 $175,000
MS $62,000 $120,000 $70,000 $252,000
NC $95,000 $45,000 $35,000 $175,000
ND $150,000 $10,000 $162,000 $322,000
PA $70,000 $95,000 $35,000 $200,000
RI $200,000 $215,000 $70,000 $485,000
TN $45,000 $120,000 $55,000 $220,000
TX $10,000 $62,000 $35,000 $107,000

The formatting looks good, now we can get the totals like we did earlier.

sum_row=df_sub[["Jan","Feb","Mar","total"]].sum()
sum_row
Jan      1462000
Feb      1507000
Mar       717000
total    3686000
dtype: int64

Convert the values to columns and format it.

df_sub_sum=pd.DataFrame(data=sum_row).T
df_sub_sum=df_sub_sum.applymap(money)
df_sub_sum
Jan Feb Mar total
0 $1,462,000 $1,507,000 $717,000 $3,686,000

Finally, add the total value to the DataFrame.

final_table = formatted_df.append(df_sub_sum)
final_table
Jan Feb Mar total
AR $150,000 $120,000 $35,000 $305,000
CA $162,000 $120,000 $35,000 $317,000
DE $150,000 $120,000 $70,000 $340,000
IA $253,000 $240,000 $70,000 $563,000
ID $70,000 $120,000 $35,000 $225,000
ME $45,000 $120,000 $10,000 $175,000
MS $62,000 $120,000 $70,000 $252,000
NC $95,000 $45,000 $35,000 $175,000
ND $150,000 $10,000 $162,000 $322,000
PA $70,000 $95,000 $35,000 $200,000
RI $200,000 $215,000 $70,000 $485,000
TN $45,000 $120,000 $55,000 $220,000
TX $10,000 $62,000 $35,000 $107,000
0 $1,462,000 $1,507,000 $717,000 $3,686,000

You’ll notice that the index is ‘0’ for the total line. We want to change that using rename .

final_table = final_table.rename(index={0:"Total"})
final_table
Jan Feb Mar total
AR $150,000 $120,000 $35,000 $305,000
CA $162,000 $120,000 $35,000 $317,000
DE $150,000 $120,000 $70,000 $340,000
IA $253,000 $240,000 $70,000 $563,000
ID $70,000 $120,000 $35,000 $225,000
ME $45,000 $120,000 $10,000 $175,000
MS $62,000 $120,000 $70,000 $252,000
NC $95,000 $45,000 $35,000 $175,000
ND $150,000 $10,000 $162,000 $322,000
PA $70,000 $95,000 $35,000 $200,000
RI $200,000 $215,000 $70,000 $485,000
TN $45,000 $120,000 $55,000 $220,000
TX $10,000 $62,000 $35,000 $107,000
Total $1,462,000 $1,507,000 $717,000 $3,686,000

Conclusion

By now, most people know that pandas can do a lot of complex manipulations on data - similar to Excel. As I have been learning about pandas, I still find myself trying to remember how to do things that I know how to do in Excel but not in pandas. I realize that this comparison may not be exactly fair - they are different tools. However, I hope to reach people that know Excel and want to learn what alternatives are out there for their data processing needs. I hope these examples will help others feel confident that they can replace a lot of their crufty Excel data manipulations with pandas.

I found this exercise helpful to cement these ideas in my mind. I hope it works for you as well. If you have other Excel tasks that you would like to learn how to do in pandas, let me know via the comments below and I will try to help.


 
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