First row to header with pandas - python

I have the following pandas dataframe df :
import pandas as pd
from io import StringIO
s = '''\
"Unnamed: 0","Unnamed: 1"
Objet,"Unités vendues"
Chaise,3
Table,2
Tabouret,1
'''
df = pd.read_csv(StringIO(s))
which looks as:
Unnamed: 0 Unnamed: 1
0 Objet Unités vendues
1 Chaise 3
2 Table 2
3 Tabouret 1
My target is to make the first row as header.
I use :
headers = df.iloc[0]
df.columns = [headers]
However, the "0" appears in index column name (which is normal, because this 0 was in the first row).
0 Objet Unités vendues
1 Chaise 3
2 Table 2
I tried to delete it in many way, but nothing work :
Neither del df.index.name from this post
Neither df.columns.name = None from this post or this one (which is the same situation)
How can I have this expected output :
Objet Unités vendues
1 Chaise 3
2 Table 2

what about defining that when you load your table in the first place?
pd.read_csv('filename', header = 1)
otherwise I guess you can just do this:
df.drop('0', axis = 1)

What worked for me.
Replace:
headers = df.iloc[0]
df.columns = [headers]
with:
headers = df.iloc[0].values
df.columns = headers
df.drop(index=0, axis=0, inplace=True)
Using .values returns the values from the row Series as a list which does not include the index value.
Reassigning the column headers then works as expected, without the 0.
Row 0 still exists so it should be removed with df.drop.

Having my data in U and my column names in Un I came up with this algorithm.
If you can shorten it, please do so.
U = pd.read_csv('U.csv', header = None) #.to_numpy()
Un = pd.read_csv('namesU.csv', header=None).T # Read your names csv, in my case they are in one column
Un = Un.append(U) # append the data U to the names
Un.reset_index(inplace=True, drop=True) # reset the index and drop the old one, so you don't have duplicated indices
Un.columns = [Un.iloc[0]] # take the names from the first row
Un.drop(index=0, inplace=True) # drop the first row
Un.reset_index(inplace=True, drop=True) # Return the index counter to start from 0
Another option:
Un = pd.read_csv('namesY.csv', header=None) # Read your names csv, in my case they are in one column
Un = list( Un[0] )
Un = pd.DataFrame(U, columns=[Un])

Using the skiprows parameter did the job for me: i.e. skiprows=N
where N = the number of rows to skip (in the above example, 1), so:
df = pd.read_csv('filename', skiprows=1)

Related

How to find and replace substrings at the end of column headers

I have the following columns, among others, in my dataframe: dom_pop', 'an_dom_n', 'an_dom_ncmplt. Equivalent columns exist in multiple dataframes, with the suffix changing. For example, in another dataframe they may be called out as pa_pop', 'an_pa_n', 'an_pa_ncmplt. I want to append '_kwh' to these cols across all my dataframes.
I wrote the following code:
cols = ['_n$', '_ncmplt', '_pop'] << the $ is added to indicate string ending in _n.
filterfuel = 'kwh'
for c in cols:
dfdom.columns = [col.replace(f'{c}', f'{c}_{filterfuel}') for col in dfdom.columns]
dfpa.columns = [col.replace(f'{c}', f'{c}_{filterfuel}') for col in dfpa.columns]
dfsw.columns = [col.replace(f'{c}', f'{c}_{filterfuel}') for col in dfsw.columns]
kwh gets appended to _ncmplt and _pop cols, but not the _n column. If I remove the $ _n gets appended but then _ncmplt looks like 'an_dom_n_kwh_cmplt'.
for df dom the corrected names should look like dom_pop_kwh', 'an_dom_n_kwh', 'an_dom_ncmplt_kwh'
Why is $ not being recongnised as an end of string parameter?
You can use np.where with a regex
cols = ['_n$', '_ncmplt', '_pop']
filterfuel = 'kwh'
pattern = fr"(?:{'|'.join(cols)})"
for df in [dfdom, dfpa, dfsw]:
df.columns = np.where(df.columns.str.contains(pattern, regex=True),
df.columns + f"_{filterfuel}", df.columns)
Output:
>>> pattern
'(?:_n$|_ncmplt|_pop)'
# dfdom = pd.DataFrame([[0]*4], columns=['dom_pop', 'an_dom_n', 'an_dom_ncmplt', 'hello'])
# After:
>>> dfdom
dom_pop_kwh an_dom_n_kwh an_dom_ncmplt_kwh hello
0 0 0 0 0

querying a multiindex pandas dataframe with slices

Assuming I have the following multiindex DF
import pandas as pd
import numpy as np
import pandas as pd
input_id = np.array(['12345'])
docType = np.array(['pre','pub','app','dw'])
docId = np.array(['34455667'])
sec_type = np.array(['bib','abs','cl','de'])
sec_ids = np.array(['x-y','z-k'])
index = pd.MultiIndex.from_product([input_id,docType,docId,sec_type,sec_ids])
content= [str(randint(1,10))+ '##' + str(randint(1,10)) for i in range(len(index))]
df = pd.DataFrame(content, index=index, columns=['content'])
df.rename_axis(index=['input_id','docType','docId','secType','sec_ids'], inplace=True)
df
I know that I can query a multiindex DF as follows:
# querying a multiindex DF
idx = pd.IndexSlice
df.loc[idx[:,['pub','pre'],:,'de',:]]
basically with the help of pd.IndexSlice I can pass the values I want for every of the indexes. In the above case I want the resulting DF where the second index is 'pub' OR 'pre' and the 4th one is 'de'.
I am looking for the way to pass a range of values to the query. something like multiindex 3 beeing between 34567 and 45657. Assume those are integers.
pseudocode: df.loc[idx[:,['pub','pre'],XXXXX,'de',:]]
XXXX = ?
EDIT 1:
docId column index is of text type, probably its necessary to change it first to int
Turns out query is very powerful:
df.query('docType in ["pub","pre"] and ("34455667" <= docId <= "3445568") and (secType=="de")')
Output:
content
input_id docType docId secType sec_ids
12345 pre 34455667 de x-y 2##9
z-k 6##1
pub 34455667 de x-y 6##5
z-k 9##8

Pandas read_csv for a no quote file

I'm trying to read a file that doesn't have any quotes, which is causing inconsistent number of row lengths
Data looks as follows:
col_a, col_b
abc, inc., 5
xyz corb, 10
Since there are no quotes around "abc, inc.", this is causing the first row to get split into 3 values, but it should actually be just 2 values.
This column is not necessarily in the first position, and that there can be another bad column like this. The data has around 250 columns.
I'm reading this using pd.read_csv, how can this be resolved?
Thanks!
Its not a CSV but since there is only one column with the errant commas you can process with the csv module and fix the slice that holds too many column values. When a row has too many cells, assume they are the ones from the unescaped comma.
import pandas as pd
import csv
def split_badrows(fileobj, bad_col, total_cols):
"""Iterate rows, colapsing extra columns at bad_col"""
for row in csv.reader(fileobj):
row = [cell.strip() for cell in row]
extras = len(row) - total_cols
if extras > 0:
# colapse slice at troubled column into single value
extras += 1 # python slice doesn't include right endpoint
row[bad_col] = ", ".join(row[bad_col:bad_col+extras])
del row[bad_col+1:bad_col+extras]
yield row
def df_from_badtext(fileobj, bad_col):
"""Make pandas.DataFrame from badly formatted text"""
columns = [cell.strip() for cell in next(fileobj).split(",")]
total_cols = len(columns)
return pd.DataFrame(split_badrows(fileobj, bad_col, total_cols),
columns=columns)
# test
open("testme.txt", "w").write("""col_a, col_b
abc, inc., 5
xyz corb, 10""")
df = df_from_badtext(open("testme.txt"), bad_col=0)
print(df)
Data split to list then transform to dataframe.
csv = '''col_a, col_b
abc, inc., 5
xyz corb, 10'''+'\n'
import re
import pandas as pd
reArr = re.findall('(.*),([^,]+)\n',csv)
df=pd.DataFrame(reArr[1:],columns=reArr[0])
print(df)
col_a
col_b
0
abc, inc.
5
1
xyz corb
10
EDIT:
Thanks to tdelaney comment below:
see if this works
pd.read_csv('foo.csv',delimiter=",(?!( [\w\d]*).,)").dropna(axis=1)
OLD:
using delimiter as ",(?!.*,)" in read_csv seems to be solving this for me
EDIT (after updated question with an additional column):
Solution 1:
You can create a function with the bad column as a parameter and use split and concat to correct the dataframe depending on that bad column. Please note that the bad_col parameter in my function is the column number, where we start counting at 1, rather than 0 (e.g. 1, 2, 3, etc. instead of 0, 1, 2, etc.):
import pandas as pd
import numpy as np
from io import StringIO
data = StringIO('''
col, col_a, col_b
000, abc, inc., 5
111, xyz corb, 10
''')
df = pd.read_csv(data, sep="|")
def fix_csv(df, bad_col):
cols = df.columns.str.split(', ')[0]
x = len(cols) - bad_col
tmp = df.iloc[:,0].str.split(', ', expand=True, n=x)
df = pd.concat([tmp.iloc[:,0],
tmp.iloc[:,-1].str.rsplit(', ', expand=True, n=x)],
axis=1)
df.columns = cols
return df
fix_csv(df, bad_col=2)
Solution 2 (this is if you have issues in multiple columns and you need to use more brute force):
It sounds like there is a possibility that you there could be multiple columns affected from the comments as you mentioned only 1 "so far".
As such, this might be a little bit of a project to clean up the data. The following code can give you an idea how to do that. The bottom-line is that you can create two different dataframes: 1) The first dataframe has the minimum number of commas (i.e. they should be the rows without any issues). 2) The other dataframe will be the dataframe with all of the issues. I've shown how you can clean the data to get to the correct number of columns and then change the data back and concat the two dataframes.
import pandas as pd
import numpy as np
from io import StringIO
data = StringIO('''
col, col_a, col_b
000, abc, inc., 5
111, xyz corb, 10
''')
df = pd.read_csv(data, sep="|")
cols = df.columns.str.split(', ')[0]
s = df.iloc[:,0].str.count(',')
df1 = df.copy()[s.eq(s.min())]
df1 = df1.iloc[:,0].str.split(', ', expand=True)
df1.columns = cols
df2 = df.copy()[s.gt(s.min())]
#inspect this dataframe manually to see how many rows affected, which columns, etc.
#cleanup df2 with some .replace so all equal commas
original = [', inc.', ', corp.']
temp = [' inc.', ' corp.']
df2.iloc[:,0] = df2.iloc[:,0].replace(original, temp, regex=True)
df2 = df2.iloc[:,0].str.split(', ', expand=True)
df2.columns = cols
#cleanup df2 by changing back to original values
df2['col_a'] = df2['col_a'].replace(temp, original, regex=True) # you can do this with other columns as well
df3 = pd.concat([df1, df2]).sort_index()
df3
Out[1]:
col col_a col_b
0 000 abc, inc. 5
1 111 xyz corb 10
Solution 3: Previous Solution (for original question when problem was only in first column - for reference)
You can read in with sep="|" as that | character is not in your .csv, so it reads all of the data into one column.
The main assumption to my solution is that the problematic column is only the first column. I use rsplit(', ') and limit the number of splits to the total number of columns minus 1 (with the example data, this is 2-1=1). Hopefully, this solves with your actual data or at least gives you some idea. If your data is separated by , instead of , , please note whether or not to adjust my splits as well.
import pandas as pd
import numpy as np
from io import StringIO
data = StringIO('''
col_a, col_b
abc, inc., 5
xyz corb, 10
''')
df = pd.read_csv(data, sep="|")
cols = df.columns.str.split(', ')[0]
x = len(cols) - 1
df = df.iloc[:,0].str.rsplit(', ', expand=True, n=x)
df.columns = cols
df
Out[1]:
col_a col_b
0 abc, inc. 5
1 xyz corb 10

Python - keep rows in dataframe based on partial string match

I have 2 dataframes :
df1 is a list of mailboxes and email ids
df2 shows a list of approved domains
I read both the dataframes from an excel sheet
xls = pd.ExcelFile(input_file_shared_mailbox)
df = pd.read_excel(xls, sheet_name = sheet_name_shared_mailbox)
i want to only keep records in df1 where df1[Email_Id] contains df2[approved_domain]
print(df1)
Mailbox Email_Id
0 mailbox1 abc#gmail.com
1 mailbox2 def#yahoo.com
2 mailbox3 ghi#msn.com
print(df2)
approved_domain
0 msn.com
1 gmail.com
and i want df3 which basically shows
print (df3)
Mailbox Email_Id
0 mailbox1 abc#gmail.com
1 mailbox3 ghi#msn.com
this is the code i have right now which i think is close but i can't figure out the exact problem in the syntax
df3 = df1[df1['Email_Id'].apply(lambda x: [item for item in x if item in df2['Approved_Domains'].tolist()])]
But get this error
TypeError: unhashable type: 'list'
i spent a lot of time researching the forum for a solution but could not find what i was looking for. appreciate all the help.
So these are the steps you will need to follow to do what you want done for your two data frames
1.Split your email_address column into two separate columns
df1['add'], df1['domain'] = df1['email_address'].str.split('#', 1).str
2.Then drop your add column to keep your data frame clean
df1 = df1.drop('add',axis =1)
3.Get a new Data Frame with only values you want by not selecting any value in the 'domain' column that doesn't match 'approved_doman' column
df_new = df1[~df1['domain'].isin(df2['approved_domain'])]
4. Drop the 'domain' column in df_new
df_new = df_new.drop('domain',axis = 1)
This is what the result will be
mailbox email_address
1 mailbox2 def#yahoo.com
2 mailbox3 ghi#msn.com
You can use dynamically created regular expression to search for the valid domain in the list and eventually filtering them out.
Here is the code for our reference.
# -*- coding: utf-8 -*-
import pandas as pd
import re
mailbox_list = [
['mailbox1', 'abc#gmail.com'],
['mailbox2', 'def#yahoo.com'],
['mailbox3', 'ghi#msn.com']]
valid_domains = ['msn.com', 'gmail.com']
df1 = pd.DataFrame(mailbox_list, columns=['Mailbox', 'EmailID'])
df2 = pd.DataFrame(valid_domains)
valid_list = []
for index, row in df1.iterrows():
for idx, record in df2.iterrows():
if re.search(rf"#{record[0]}", row[1], re.IGNORECASE):
valid_list.append([row[0], row[1]])
df3 = pd.DataFrame(valid_list, columns=['Mailbox', 'EmailID'])
print(df3)
The output of this is:
Mailbox EmailID
0 mailbox1 abc#gmail.com
1 mailbox3 ghi#msn.com
Solution
df1 = {'MailBox': ['mailbox1', 'mailbox2', 'mailbox3'], 'Email_Id': ['abc#gmail.com', 'def#yahoo.com', 'ghi#msn.com']}
df2 = {'approved_domain':['msn.com', 'gmail.com']}
mailboxes, emails = zip( # unzip the columns
*filter( # filter
lambda i: any([ # i = ('mailbox1', 'abc#gmail.com')
approved_domain in i[1] for approved_domain in df2['approved_domain']
]),
zip(df1['MailBox'], df1['Email_Id']) # zip the columns
)
)
df3 = {
'MailBox': mailboxes,
'Email_I': emails
}
print(df3)
Output:
> {'Email_ID': ('abc#gmail.com', 'ghi#msn.com'), 'MailBox': ('mailbox1', 'mailbox3')}
Some notes:
Big chunk of this code is basically just for parsing the data structure. The zipping and unzipping is only there to convert the list of columns to a list of rows and back. If you have a a list of rows already, you just have to do the filtering part

How can I split a column into 2 in the correct way?

I am web-scraping tables from a website, and I am putting it to the Excel file.
My goal is to split a columns into 2 columns in the correct way.
The columns what i want to split: "FLIGHT"
I want this form:
First example: KL744 --> KL and 0744
Second example: BE1013 --> BE and 1013
So, I need to separete the FIRST 2 character (in the first column), and after that the next characters which are 1-2-3-4 characters. If 4 it's oke, i keep it, if 3, I want to put a 0 before it, if 2 : I want to put 00 before it (so my goal is to get 4 character/number in the second column.)
How Can I do this?
Here my relevant code, which is already contains a formatting code.
df2 = pd.DataFrame(datatable,columns = cols)
df2["UPLOAD_TIME"] = datetime.now()
mask = np.column_stack([df2[col].astype(str).str.contains(r"Scheduled", na=True) for col in df2])
df3 = df2.loc[~mask.any(axis=1)]
if os.path.isfile("output.csv"):
df1 = pd.read_csv("output.csv", sep=";")
df4 = pd.concat([df1,df3])
df4.to_csv("output.csv", index=False, sep=";")
else:
df3.to_csv
df3.to_csv("output.csv", index=False, sep=";")
Here the excel prt sc from my table:
You can use indexing with str with zfill:
df = pd.DataFrame({'FLIGHT':['KL744','BE1013']})
df['a'] = df['FLIGHT'].str[:2]
df['b'] = df['FLIGHT'].str[2:].str.zfill(4)
print (df)
FLIGHT a b
0 KL744 KL 0744
1 BE1013 BE 1013
I believe in your code need:
df2 = pd.DataFrame(datatable,columns = cols)
df2['a'] = df2['FLIGHT'].str[:2]
df2['b'] = df2['FLIGHT'].str[2:].str.zfill(4)
df2["UPLOAD_TIME"] = datetime.now()
...
...

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