Wilcoxon W value different from python
If you look at the wikipedia page of Wilcoxon signed-rank test, under the section of the original test, it's mentioned that 


  The original Wilcoxon's proposal used a different statistic. Denoted by Siegel as the $T$ statistic, it is the smaller of the two sums of ranks of given sign; in the example given below, therefore, $T$ would equal $3+4+5+6=18$