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Spark By {Examples}
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Pandas Replace Substring in DataFrame - Spark By {Examples}
June 6, 2025 - You can find how to replace substrings in a pandas DataFrame column using the replace() method with lambda functions. This versatile method allows you to
Discussions

Replace part of string in a column if string is at a certain position in Pandas
How about this: output_table_1["newcol"] = output_table_1["Reference"].str.split("[ -]", expand=True)[0] This splits on either space or hyphen, expands to a dataframe, then takes the first column of that result and assigns it to newcol. More on reddit.com
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October 26, 2022
python - Replacing Substring with another string from column Pandas - Stack Overflow
For each value on String column, I need to replace the substring 'id' (UKidBC) according to the following rule: If df['Type'] = 1 then replace substring 'id' with the corresponding df['int_id'] value else replace substring 'id' with the corresponding df['ext_id'] value. More on stackoverflow.com
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March 13, 2022
python - Pandas DataFrame - replace substring in column if a substring exists - Stack Overflow
I am trying to update DataFrame column names if a substring exists within the column name, however I only need to update the substring, retaining all information either side of it. Example: import ... More on stackoverflow.com
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March 18, 2022
replace substring in pandas data frame column - Stack Overflow
I am working with dataframe that contains column named "raw_parameter_name". In this column i have different string values. Several values are like following pattern "ABCD;MEAN". What i am trying ... More on stackoverflow.com
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October 2, 2015
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Pandas
pandas.pydata.org › docs › reference › api › pandas.DataFrame.replace.html
pandas.DataFrame.replace — pandas 3.0.6 documentation
Map values of Series according to an input mapping or function. ... Simple string replacement. ... Regex substitution is performed under the hood with re.sub. The rules for substitution for re.sub are the same. Regular expressions will only substitute on strings, meaning you cannot provide, for example, a regular expression matching floating point numbers and expect the columns in your frame that have a numeric dtype to be matched.
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DataScience Made Simple
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Replace substring/pattern of column in pandas python - DataScience Made Simple
July 28, 2023 - Replace a substring of a column in pandas python can be done by replace() funtion. Let’s see how to Replace a substring with another substring in pandas ..
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Spark By {Examples}
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How to Replace String in Pandas DataFrame - Spark By {Examples}
June 13, 2025 - In pandas, to replace a string in the DataFrame column, you can use either the replace() function or the str.replace() method along with lambda methods.
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Pandas
pandas.pydata.org › docs › reference › api › pandas.Series.str.replace.html
pandas.Series.str.replace — pandas 3.0.6 documentation
If True, assumes the passed-in pattern is a regular expression. ... Cannot be set to False if pat is a compiled regex or repl is a callable. ... A copy of the object with all matching occurrences of pat replaced by repl. ... Method to replace occurrences of a substring with another substring.
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GeeksforGeeks
geeksforgeeks.org › python › replace-characters-in-strings-in-pandas-dataframe
Replace Characters in Strings in Pandas DataFrame - GeeksforGeeks
July 23, 2025 - Note that this approach may not be as efficient as using the replace method, as it requires the creation of a new function for each element in the column. However, it can be useful in cases where the replace method is not suitable or when you need to perform more complex string manipulation operations. ... import pandas as pd def replace_char(s): return s.replace('_', '+') data = {'Student_Full_Name': ['Mukul_Jatav', 'Rahul_Shukla', 'Robin_Singh', 'Mayank_Sharma', 'Akash_Verma'], 'Father_Full_name': ['Mukesh_Jatav', 'Siddhart_Shukla', 'Rohit_Singh', 'Sunil_Sharma', 'Rajesh_Verma'] } df = pd.DataFrame(data, columns=['Student_Full_Name', 'Father_Full_name']) df['Student_Full_Name'] = df['Student_Full_Name'].apply(lambda x: x.replace('_', '+')) print(df)
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Reddit
reddit.com › r/learnpython › replace part of string in a column if string is at a certain position in pandas
r/learnpython on Reddit: Replace part of string in a column if string is at a certain position in Pandas
October 26, 2022 -

I have this sample column:

Reference
A3V345 1/2
763SDDY 2/2
645BRW0 1OF4
645BRW0 2OF4
GRYUGBM-A
67AQSD-B
EW21Z31
4GH5477BM 1/3

I would like to create a new column where the result is the same value in the reference column with "-B, -A, 2OF4, 1OF4, 2/2, 1/2" removed or replaced with ""; the desired output would be this:

new_value
A3V345
763SDDY
645BRW0
645BRW0
GRYUGBM
67AQSD
EW21Z31
4GH5477BM

So far I have attempted at least three different things with different error messages in the output:

1. str.endswith and concatenation of strings to identify position and somehow slice value after True value in cell

output_table_1["new_value"] = output_table_1["Reference"].str.endswith((" 1/2", " 2/2", " 1/3", "1OF4", "2OF4", "-A", "-B"), na = False)
output_table_1["concat"] = output_table_1["Reference"] + str(output_table_1["new_value"])
output_table_1

The output is a long text I didn't expect to see, for instance, for 4GH5477BM this is the result:

4GH5477BM 1/30 False\n1 False\n2 False\n3 False\n4 False\n ... 

Cell expanded: 4GH5477BM 1/30 False\n1 False\n2 False\n3 False\n4 False\n ... \n1014 False\n1015 False\n1016 False\n1017 True\n1018 True\nName: new_value, Length: 1019, dtype: bool

2. str.replace if condition (only one parameter as example) applies

if output_table_1[output_table_1["Reference"].str.endswith(" 1/2", na=False)]:
    output_table_1["new_value"] = output_table_1["Reference"].apply(lambda x: x.replace(" 1/2", ""))
else:
    output_table_1["new_value"] = output_table_1["Reference"]
Output:
ValueError: The truth value of a DataFrame is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

3. str.find to check position at the end of string

positionA = output_table_1["Reference"].str.len() - 4
positionB = output_table_1["Reference"].str.len()
output_table_1["set_value"] = output_table_1["Reference"].str.find(" 1/2", start = positionA, end = positionB)

The output is NaN for all the cells in that column, even though I believe it should return -1 if there was no match when searching the substring. Even if it worked, I still would be limited as it only accepts one string to search. As in the first try, I wanted to return the index where the occurrence happened and then use slicing to delete just before the searched substring.

I still lack skill in Python, more so in Pandas. Any help will be appreciated.

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Medium
medium.com › data-science › an-easy-way-to-replace-values-in-a-pandas-dataframe-2826bd34e59a
An Easy Way to Replace Values in a Pandas DataFrame | by Byron Dolon | TDS Archive | Medium
July 25, 2021 - To do this, Pandas provides a wide range of methods that you can use to work with columns of all data types in your DataFrames. In this piece, let’s take a look specifically at replacing values and sub-strings within columns in a DataFrame.
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GeeksforGeeks
geeksforgeeks.org › pandas › python-pandas-series-str-replace-to-replace-text-in-a-series
Python | Pandas Series.str.replace() to replace text in a series - GeeksforGeeks
July 11, 2025 - Example: The .str.replace() method is a part of the Pandas String Handling capabilities. This let users to replace occurrences of a specified substring with another substring in text data contained within a Pandas Series.
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Statology
statology.org › home › how to use str.replace in pandas (with examples)
How to Use str.replace in Pandas (With Examples)
April 11, 2024 - ### Suggested Simplification If your goal is simply to extract the substring from position 19 to 24 and update the column, you can simplify your code to: “`python df[‘columnname’] = df[‘columnname’].str[19:24] “` This will update the `’columnname’` column with just the extracted substrings while leaving the rest of the DataFrame unchanged.
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Vultr Docs
docs.vultr.com › python › third-party › pandas › Series › str › replace
Python Pandas Series str replace() - Replace Substring | Vultr Docs
November 26, 2024 - import pandas as pd data = pd.Series(['foo', 'bar', 'baz', 'foobar']) modified_data = data.str.replace('foo', 'new') print(modified_data) Explain Code · This example replaces the substring 'foo' with 'new' in each element of the Series.
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Note.nkmk.me
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pandas: Handle strings (replace, strip, case conversion, etc.) | note.nkmk.me
April 23, 2022 - pandas: Slice substrings from each element in columns · import pandas as pd s = pd.Series([' a-a-x ', ' b-x-b ', ' x-c-c ']) print(s) # 0 a-a-x # 1 b-x-b # 2 x-c-c # dtype: object s_new = s.str.replace('x', 'z') print(s_new) # 0 a-a-z # 1 b-z-b # 2 z-c-c # dtype: object
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Towards Data Science
towardsdatascience.com › home › latest › 2 different replace functions of python pandas
2 Different Replace Functions of Python Pandas | Towards Data Science
January 20, 2025 - ... The replace function available via the str accessor can be used for replacing a part or subsequence of a string. Accessors in Pandas provide functions specific to a particular data type.
Top answer
1 of 3
5

use str.contains to create a boolean index to mask the series and then str.replace to replace your substring:

In [172]:
df = pd.DataFrame({'raw_parameter_name':['ABCD;MEAN', 'EFGH;MEAN', '1234;MEAN', 'sdasd;MEAT']})
df

Out[172]:
  raw_parameter_name
0          ABCD;MEAN
1          EFGH;MEAN
2          1234;MEAN
3         sdasd;MEAT

In [173]:
df.loc[df['raw_parameter_name'].str.contains(';MEAN$'), 'raw_parameter_name'] = df['raw_parameter_name'].str.replace('MEAN', 'X-BAR')
df

Out[173]:
  raw_parameter_name
0           ABCD;X-BAR
1           EFGH;X-BAR
2           1234;X-BAR
3         sdasd;MEAT

Here it matches where the substrin ';MEAN' exists the $ is a terminating symbol

The boolean mask looks like the following:

In [176]:
df['raw_parameter_name'].str.contains(';MEAN$')

Out[176]:
0     True
1     True
2     True
3    False
Name: raw_parameter_name, dtype: bool

Timings

For a 40,0000 row df using str.replace is faster than using apply:

In [183]:
import re
%timeit df['raw_parameter_name'].apply(lambda x: re.sub(';MEAN$',';X-BAR',x))
%timeit df['raw_parameter_name'].str.replace('MEAN', 'X-BAR')
​
1 loops, best of 3: 1.01 s per loop
1 loops, best of 3: 687 ms per loop
2 of 3
2

You can use regex module re for example:

import pandas as pd
import re

df = pd.DataFrame({"row_parameter_name":['abcd;MEAN','Dogg11;MEAN',';MEAN']})

Out[126]:
  row_parameter_name
0          abcd;MEAN
1        Dogg11;MEAN
2              ;MEAN 

df['row_parameter_name'] = df['row_parameter_name'].apply(lambda x: re.sub(';MEAN$',';X-BAR',x))

In [128]: df
Out[128]:
  row_parameter_name
0         abcd;X-BAR
1       Dogg11;X-BAR
2             ;X-BAR