如何快速重新映射到连续的数字 [英] How to remap ids to consecutive numbers quickly
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问题描述
stringa,stringb
stringb,stringc
stringd,stringa
我需要转换它,以便id从0连续编号。在此案例如下:
0,1
1,2
3,0
我目前的代码如下:
code> import csv
names = {}
counter = 0
with open('foo.csv','rb')as csvfile:
reader = csv。读者(csvfile)
读者中的行
如果行[0]在名称中:
id1 =行[0]
其他:
名称[row [0 ]] = counter
id1 = counter
counter + = 1
如果名称中的行[1]:
id2 = row [1]
else:
名称[row [1]] = counter
id2 = counter
counter + = 1
print id1,id2
/ pre>
Python的dache使用了很多内存,我的输入很大。
如果输入太大以致于无法适应内存,我该怎么办?
如果有的话我也会感兴趣是一个更好/更快的方式来解决这个问题。
解决方案
df = pd .DataFrame([['a','b'],['b','c'],['d','a']])
v = df.stack()。 unique()
v.sort()
f = pd.factorize(v)
m = pd.Series(f [0],f [1])$ b
$ b df.stack()。map(m).unstack()
I have a large csv file with lines that looks like
stringa,stringb stringb,stringc stringd,stringa
I need to convert it so the ids are consecutively numbered from 0. In this case the following would work
0,1 1,2 3,0
My current code looks like:
import csv names = {} counter = 0 with open('foo.csv', 'rb') as csvfile: reader = csv.reader(csvfile) for row in reader: if row[0] in names: id1 = row[0] else: names[row[0]] = counter id1 = counter counter += 1 if row[1] in names: id2 = row[1] else: names[row[1]] = counter id2 = counter counter += 1 print id1, id2
Python dicts use a lot of memory sadly and my input is large.
What can I do when the input is too large for the dict to fit in memory
I would also be interested if there is a better/faster way to solve this problem in general.
解决方案df = pd.DataFrame([['a', 'b'], ['b', 'c'], ['d', 'a']]) v = df.stack().unique() v.sort() f = pd.factorize(v) m = pd.Series(f[0], f[1]) df.stack().map(m).unstack()
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