问题描述
我正在使用libsvm预测情绪.我想知道输入必须采用什么格式假设我正在使用字数统计.
I am using libsvm to predict sentiment. I wanted to know what format the input has to be inassuming I am using word count.
[label] [index]:[value] [index]:[value]
这是libsvm中的必需格式.那是否意味着我只有两个标签(一个用于正数，一个用于负数)，索引将是该标签下的每个单词，而值将是每个单词的出现频率?
That is required format from libsvm. So does that mean I just have two labels ( one for positive and one for negative), the index would be each word under that label and the value would be the frequency of each word ?
这是否还意味着我需要存储单词到索引的映射以在测试集中使用?
Does this also mean I need to store the mapping of word to index to use in my test set ?
推荐答案
LIBSVM使用所谓的稀疏"格式，其中不需要存储零值.因此，具有属性的数据
5 0 2 0
表示为
1:5 3:2
因此，您只需要指定 nonzero 属性的 index 和 value .
LIBSVM uses the so called "sparse" format where zero values do not need to be stored. Hence a data with attributes
5 0 2 0
is represented as
1:5 3:2
Therefore, you only need to specifiy the index and the value of nonzero attributes.
标签位于第一列.对于二进制情况，您可以将+1用于正样本，将-1用于负样本.顺便说一句，您不仅限于2个标签.您可以使用其他数字(例如1,2,3,4,5，...)
Labels stand in the first column. For binary cases you may use +1 for positive and -1 for negative samples. By the way, you are not limited to only 2 labels. You can use other numbers (e.g. 1,2,3,4,5,...)
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