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Pandas's dataframe condition Filter performance Optimization?
currently I have a piece of code that spends most of its time on the above two sentences of data filtering in dataframe. temp_df = df [df [ "data_date "] .isin (date_list)] temp = temp_df [rule [2]] [temp_df [ "data_date "] = = d]
at present, it tak...
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UnicodeDecodeError: 'utf-8' codec can't decode byte 0xaa
how to deal with decoding errors when reading files? ...
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The meaning of pandas
import pandas as pd word = pd.read_table ( test.txt , encoding = utf-8 , names = [ query ])
what does the query in the names here mean?
header: int, list of ints, default infer
Row number (s) to use as the column names, and the s...
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Problems with reading unicode-encoded txt files by python pandas.dataframe
I have a txt file encoded in unicode,
:
1.with open( STK_MKT_ValuationMetrics.txt , rb ) as f:: utf-8 codec can t decode byte 0xff in position 0: invalid start byte2.with open( STK_MKT_ValuationMetrics.txt , rb ,encoding= utf-8 ) as ...
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How does pandas clean data elements whose values are strings in a column?
the value in the figure is "pass "
After pandas reads the csv file, I want to delete the data line whose value is a string in the kscj column. What should I do?
...
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How can pandas read csv files to avoid the impact of scientific counting on grouping?
csv`import numpy as npimport pandas as pdf=open( G:XueYegrades.csv , rb )df=pd.read_csv(f,low_memory=False,usecols=[0,1,3,4,5,7,8,15,16])group=df.groupby([ xh , xm ],sort=False)[ xf ]print(group.sum())`
as a result, he counted the student n...
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Mysql Connector python,NotSupportedError
to export a batch of Json data from Mongodb, you need to transfer to Mysql, but the exported Json format cannot be directly written to mysql, so you want to convert the data to Pandas s dataframe, and then write to sql: through dataframe .
import panda...
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Why is there an extra output for apply after using groupby in pandas?
df = pd.DataFrame([[4, 9],[4, 2], [4, 5], [5, 4]], columns=[ A , B ])
df.groupby([ A ]).apply(lambda x : print(x, n ))
df is:
A B
0 4 9
1 4 2
2 4 5
3 5 4
the output after using apply is as follows:
A B
0 4 9
...
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How does pandas write data completely in the sheet of an existing excel? How does pandas delete a row of data in excel?
when using pandas for file writing, if the original sheet already has data, the newly written data is overwritten on the original data without deletion. For example, there are 4 rows of data originally, and I want to delete one row. After read is datafr...
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Baidu interview questions, how to quickly find out the duplicates in the file (large files can not be read at one time)?
Baidu interview questions, roughly means that there is a file, the file is very large can not be read at one time (may not be loaded into memory), the file is stored in the IP address, how to quickly find the duplicate IP address? Ask for advice.
The ...
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Pandas multiple grouping statistics
Ladies and Gentlemen, I would like to ask you a Pandas grouping question, which I feel is more complicated.
df = pd.DataFrame({"Date":pd.date_range(start= 2018-08-17 08:10:30 ,periods=15,freq= s ,normalize=True),"Category":list(...
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Abnormalities in the comparison of two groups of numpy data
1. When I am converting the real data of two dataframe tables into numpy data for column content comparison, I encounter the following situations: input:
individual elements of different arrays
d12.values [0] [0], d12.values [1] [0], d11.values [...
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How does pandas convert the df of figure 1 to the df of figure 2
I wrote a part here, that is to say, first convert the original df into a dictionary, and then create a new dictionary and then operate on these two dictionaries, but there seems to be a problem with the result of a large amount of data .
...
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The speed of pandas read_sql is too slow. It takes about 10 seconds for 10W rows of data. Is there any optimization plan?
pandas read_sql is too slow
10W rows of data take about 10 seconds. Is there an optimization plan ?
...
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How do I display the columns specified in the DateFrame?
use pandas s read_csv to read a dataset
import pandas as pd dfoff = pd.read_csv (xxx.csv , keep_default_na=False) pd.set_option ( display.max_columns , None) print (dfoff.head (3))
found that he has 6 columns of data
User_id
print(dfof...
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Python time processing: know the start time and end time, count the number of times per minute
know the start time and end time of each sample, as shown in the following figure:
hu is the unique value of the sample. It is known that time1 and time2 are the start time and end time of the behavior, respectively. Now, we want to count the number...
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Pandas multi-conditional grouping scheduling problem row_number
df = pd.DataFrame({ key1 : [ a , a , a , b , b ],
key2 : [ c , d , c , c , d ],
data : [1,10,2,3,30]})
>>> df
key1 key2 data
0 a c 1
1 a d 10
2 a c 2
3 b c 3
4 ...
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How do the DataFrame objects of Pandas group and sort and retain the order of the groups?
encountered a problem and simplified it.
has a dataframe
df = pd.DataFrame([[ a , 1, c ], [ a , 3, a ], [ a , 2, b ],
[ c , 3, a ], [ c , 2, b ], [ c , 1, c ],
[ b , 2, b ], [ ...
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How does pandas delete the row where a column of data conforms to a regular expression?
two columns of existing data, as shown in the following figure:
then I want to delete the data in column a that matches a regular expression (such as the beginning of 0002). How should I write it?
add: the above is just an example, because it doe...
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In Pandas, the order of variables changes unexpectedly after adding Series to the empty DataFrame?
the reason has been found. The order of variables from append to the data box will be adjusted automatically when the column tag of DataFrame is not set beforehand.
df = pd.DataFrame()
series=pd.Series([3,4,1,6],index=[ b , a , d , c ])
df=df.a...
